1 /** @file
2   The EFI Legacy BIOS Protocol is used to abstract legacy Option ROM usage
3   under EFI and Legacy OS boot.  This file also includes all the related
4   COMPATIBILIY16 structures and defintions.
5 
6   Note: The names for EFI_IA32_REGISTER_SET elements were picked to follow
7   well known naming conventions.
8 
9   Thunk is the code that switches from 32-bit protected environment into the 16-bit real-mode
10   environment. Reverse thunk is the code that does the opposite.
11 
12 Copyright (c) 2007 - 2018, Intel Corporation. All rights reserved.<BR>
13 SPDX-License-Identifier: BSD-2-Clause-Patent
14 
15   @par Revision Reference:
16   This protocol is defined in Framework for EFI Compatibility Support Module spec
17   Version 0.98.
18 
19 **/
20 
21 #ifndef _EFI_LEGACY_BIOS_H_
22 #define _EFI_LEGACY_BIOS_H_
23 
24 ///
25 ///
26 ///
27 #pragma pack(1)
28 
29 typedef UINT8                       SERIAL_MODE;
30 typedef UINT8                       PARALLEL_MODE;
31 
32 #define EFI_COMPATIBILITY16_TABLE_SIGNATURE SIGNATURE_32 ('I', 'F', 'E', '$')
33 
34 ///
35 /// There is a table located within the traditional BIOS in either the 0xF000:xxxx or 0xE000:xxxx
36 /// physical address range. It is located on a 16-byte boundary and provides the physical address of the
37 /// entry point for the Compatibility16 functions. These functions provide the platform-specific
38 /// information that is required by the generic EfiCompatibility code. The functions are invoked via
39 /// thunking by using EFI_LEGACY_BIOS_PROTOCOL.FarCall86() with the 32-bit physical
40 /// entry point.
41 ///
42 typedef struct {
43   ///
44   /// The string "$EFI" denotes the start of the EfiCompatibility table. Byte 0 is "I," byte
45   /// 1 is "F," byte 2 is "E," and byte 3 is "$" and is normally accessed as a DWORD or UINT32.
46   ///
47   UINT32                            Signature;
48 
49   ///
50   /// The value required such that byte checksum of TableLength equals zero.
51   ///
52   UINT8                             TableChecksum;
53 
54   ///
55   /// The length of this table.
56   ///
57   UINT8                             TableLength;
58 
59   ///
60   /// The major EFI revision for which this table was generated.
61   ///
62   UINT8                             EfiMajorRevision;
63 
64   ///
65   /// The minor EFI revision for which this table was generated.
66   ///
67   UINT8                             EfiMinorRevision;
68 
69   ///
70   /// The major revision of this table.
71   ///
72   UINT8                             TableMajorRevision;
73 
74   ///
75   /// The minor revision of this table.
76   ///
77   UINT8                             TableMinorRevision;
78 
79   ///
80   /// Reserved for future usage.
81   ///
82   UINT16                            Reserved;
83 
84   ///
85   /// The segment of the entry point within the traditional BIOS for Compatibility16 functions.
86   ///
87   UINT16                            Compatibility16CallSegment;
88 
89   ///
90   /// The offset of the entry point within the traditional BIOS for Compatibility16 functions.
91   ///
92   UINT16                            Compatibility16CallOffset;
93 
94   ///
95   /// The segment of the entry point within the traditional BIOS for EfiCompatibility
96   /// to invoke the PnP installation check.
97   ///
98   UINT16                            PnPInstallationCheckSegment;
99 
100   ///
101   /// The Offset of the entry point within the traditional BIOS for EfiCompatibility
102   /// to invoke the PnP installation check.
103   ///
104   UINT16                            PnPInstallationCheckOffset;
105 
106   ///
107   /// EFI system resources table. Type EFI_SYSTEM_TABLE is defined in the IntelPlatform
108   ///Innovation Framework for EFI Driver Execution Environment Core Interface Specification (DXE CIS).
109   ///
110   UINT32                            EfiSystemTable;
111 
112   ///
113   /// The address of an OEM-provided identifier string. The string is null terminated.
114   ///
115   UINT32                            OemIdStringPointer;
116 
117   ///
118   /// The 32-bit physical address where ACPI RSD PTR is stored within the traditional
119   /// BIOS. The remained of the ACPI tables are located at their EFI addresses. The size
120   /// reserved is the maximum for ACPI 2.0. The EfiCompatibility will fill in the ACPI
121   /// RSD PTR with either the ACPI 1.0b or 2.0 values.
122   ///
123   UINT32                            AcpiRsdPtrPointer;
124 
125   ///
126   /// The OEM revision number. Usage is undefined but provided for OEM module usage.
127   ///
128   UINT16                            OemRevision;
129 
130   ///
131   /// The 32-bit physical address where INT15 E820 data is stored within the traditional
132   /// BIOS. The EfiCompatibility code will fill in the E820Pointer value and copy the
133   /// data to the indicated area.
134   ///
135   UINT32                            E820Pointer;
136 
137   ///
138   /// The length of the E820 data and is filled in by the EfiCompatibility code.
139   ///
140   UINT32                            E820Length;
141 
142   ///
143   /// The 32-bit physical address where the $PIR table is stored in the traditional BIOS.
144   /// The EfiCompatibility code will fill in the IrqRoutingTablePointer value and
145   /// copy the data to the indicated area.
146   ///
147   UINT32                            IrqRoutingTablePointer;
148 
149   ///
150   /// The length of the $PIR table and is filled in by the EfiCompatibility code.
151   ///
152   UINT32                            IrqRoutingTableLength;
153 
154   ///
155   /// The 32-bit physical address where the MP table is stored in the traditional BIOS.
156   /// The EfiCompatibility code will fill in the MpTablePtr value and copy the data
157   /// to the indicated area.
158   ///
159   UINT32                            MpTablePtr;
160 
161   ///
162   /// The length of the MP table and is filled in by the EfiCompatibility code.
163   ///
164   UINT32                            MpTableLength;
165 
166   ///
167   /// The segment of the OEM-specific INT table/code.
168   ///
169   UINT16                            OemIntSegment;
170 
171   ///
172   /// The offset of the OEM-specific INT table/code.
173   ///
174   UINT16                            OemIntOffset;
175 
176   ///
177   /// The segment of the OEM-specific 32-bit table/code.
178   ///
179   UINT16                            Oem32Segment;
180 
181   ///
182   /// The offset of the OEM-specific 32-bit table/code.
183   ///
184   UINT16                            Oem32Offset;
185 
186   ///
187   /// The segment of the OEM-specific 16-bit table/code.
188   ///
189   UINT16                            Oem16Segment;
190 
191   ///
192   /// The offset of the OEM-specific 16-bit table/code.
193   ///
194   UINT16                            Oem16Offset;
195 
196   ///
197   /// The segment of the TPM binary passed to 16-bit CSM.
198   ///
199   UINT16                            TpmSegment;
200 
201   ///
202   /// The offset of the TPM binary passed to 16-bit CSM.
203   ///
204   UINT16                            TpmOffset;
205 
206   ///
207   /// A pointer to a string identifying the independent BIOS vendor.
208   ///
209   UINT32                            IbvPointer;
210 
211   ///
212   /// This field is NULL for all systems not supporting PCI Express. This field is the base
213   /// value of the start of the PCI Express memory-mapped configuration registers and
214   /// must be filled in prior to EfiCompatibility code issuing the Compatibility16 function
215   /// Compatibility16InitializeYourself().
216   /// Compatibility16InitializeYourself() is defined in Compatability16
217   /// Functions.
218   ///
219   UINT32                            PciExpressBase;
220 
221   ///
222   /// Maximum PCI bus number assigned.
223   ///
224   UINT8                             LastPciBus;
225 
226   ///
227   /// Start Address of Upper Memory Area (UMA) to be set as Read/Write. If
228   /// UmaAddress is a valid address in the shadow RAM, it also indicates that the region
229   /// from 0xC0000 to (UmaAddress - 1) can be used for Option ROM.
230   ///
231   UINT32                            UmaAddress;
232 
233   ///
234   /// Upper Memory Area size in bytes to be set as Read/Write. If zero, no UMA region
235   /// will be set as Read/Write (i.e. all Shadow RAM is set as Read-Only).
236   ///
237   UINT32                            UmaSize;
238 
239   ///
240   /// Start Address of high memory that can be used for permanent allocation. If zero,
241   /// high memory is not available for permanent allocation.
242   ///
243   UINT32                            HiPermanentMemoryAddress;
244 
245   ///
246   /// Size of high memory that can be used for permanent allocation in bytes. If zero,
247   /// high memory is not available for permanent allocation.
248   ///
249   UINT32                            HiPermanentMemorySize;
250 } EFI_COMPATIBILITY16_TABLE;
251 
252 ///
253 /// Functions provided by the CSM binary which communicate between the EfiCompatibility
254 /// and Compatability16 code.
255 ///
256 /// Inconsistent with the specification here:
257 /// The member's name started with "Compatibility16" [defined in Intel Framework
258 /// Compatibility Support Module Specification / 0.97 version]
259 /// has been changed to "Legacy16" since keeping backward compatible.
260 ///
261 typedef enum {
262   ///
263   /// Causes the Compatibility16 code to do any internal initialization required.
264   /// Input:
265   ///   AX = Compatibility16InitializeYourself
266   ///   ES:BX = Pointer to EFI_TO_COMPATIBILITY16_INIT_TABLE
267   /// Return:
268   ///   AX = Return Status codes
269   ///
270   Legacy16InitializeYourself    = 0x0000,
271 
272   ///
273   /// Causes the Compatibility16 BIOS to perform any drive number translations to match the boot sequence.
274   /// Input:
275   ///   AX = Compatibility16UpdateBbs
276   ///   ES:BX = Pointer to EFI_TO_COMPATIBILITY16_BOOT_TABLE
277   /// Return:
278   ///   AX = Returned status codes
279   ///
280   Legacy16UpdateBbs             = 0x0001,
281 
282   ///
283   /// Allows the Compatibility16 code to perform any final actions before booting. The Compatibility16
284   /// code is read/write.
285   /// Input:
286   ///   AX = Compatibility16PrepareToBoot
287   ///   ES:BX = Pointer to EFI_TO_COMPATIBILITY16_BOOT_TABLE structure
288   /// Return:
289   ///   AX = Returned status codes
290   ///
291   Legacy16PrepareToBoot         = 0x0002,
292 
293   ///
294   /// Causes the Compatibility16 BIOS to boot. The Compatibility16 code is Read/Only.
295   /// Input:
296   ///   AX = Compatibility16Boot
297   /// Output:
298   ///   AX = Returned status codes
299   ///
300   Legacy16Boot                  = 0x0003,
301 
302   ///
303   /// Allows the Compatibility16 code to get the last device from which a boot was attempted. This is
304   /// stored in CMOS and is the priority number of the last attempted boot device.
305   /// Input:
306   ///   AX = Compatibility16RetrieveLastBootDevice
307   /// Output:
308   ///   AX = Returned status codes
309   ///   BX = Priority number of the boot device.
310   ///
311   Legacy16RetrieveLastBootDevice = 0x0004,
312 
313   ///
314   /// Allows the Compatibility16 code rehook INT13, INT18, and/or INT19 after dispatching a legacy OpROM.
315   /// Input:
316   ///   AX = Compatibility16DispatchOprom
317   ///   ES:BX = Pointer to EFI_DISPATCH_OPROM_TABLE
318   /// Output:
319   ///   AX = Returned status codes
320   ///   BX = Number of non-BBS-compliant devices found. Equals 0 if BBS compliant.
321   ///
322   Legacy16DispatchOprom         = 0x0005,
323 
324   ///
325   /// Finds a free area in the 0xFxxxx or 0xExxxx region of the specified length and returns the address
326   /// of that region.
327   /// Input:
328   ///   AX = Compatibility16GetTableAddress
329   ///   BX = Allocation region
330   ///       00 = Allocate from either 0xE0000 or 0xF0000 64 KB blocks.
331   ///       Bit 0 = 1 Allocate from 0xF0000 64 KB block
332   ///       Bit 1 = 1 Allocate from 0xE0000 64 KB block
333   ///   CX = Requested length in bytes.
334   ///   DX = Required address alignment. Bit mapped. First non-zero bit from the right is the alignment.
335   /// Output:
336   ///   AX = Returned status codes
337   ///   DS:BX = Address of the region
338   ///
339   Legacy16GetTableAddress       = 0x0006,
340 
341   ///
342   /// Enables the EfiCompatibility module to do any nonstandard processing of keyboard LEDs or state.
343   /// Input:
344   ///   AX = Compatibility16SetKeyboardLeds
345   ///   CL = LED status.
346   ///     Bit 0  Scroll Lock 0 = Off
347   ///     Bit 1  NumLock
348   ///     Bit 2  Caps Lock
349   /// Output:
350   ///     AX = Returned status codes
351   ///
352   Legacy16SetKeyboardLeds       = 0x0007,
353 
354   ///
355   /// Enables the EfiCompatibility module to install an interrupt handler for PCI mass media devices that
356   /// do not have an OpROM associated with them. An example is SATA.
357   /// Input:
358   ///   AX = Compatibility16InstallPciHandler
359   ///   ES:BX = Pointer to EFI_LEGACY_INSTALL_PCI_HANDLER structure
360   /// Output:
361   ///   AX = Returned status codes
362   ///
363   Legacy16InstallPciHandler     = 0x0008
364 } EFI_COMPATIBILITY_FUNCTIONS;
365 
366 
367 ///
368 /// EFI_DISPATCH_OPROM_TABLE
369 ///
370 typedef struct {
371   UINT16  PnPInstallationCheckSegment;  ///< A pointer to the PnpInstallationCheck data structure.
372   UINT16  PnPInstallationCheckOffset;   ///< A pointer to the PnpInstallationCheck data structure.
373   UINT16  OpromSegment;                 ///< The segment where the OpROM was placed. Offset is assumed to be 3.
374   UINT8   PciBus;                       ///< The PCI bus.
375   UINT8   PciDeviceFunction;            ///< The PCI device * 0x08 | PCI function.
376   UINT8   NumberBbsEntries;             ///< The number of valid BBS table entries upon entry and exit. The IBV code may
377                                         ///< increase this number, if BBS-compliant devices also hook INTs in order to force the
378                                         ///< OpROM BIOS Setup to be executed.
379   UINT32  BbsTablePointer;              ///< A pointer to the BBS table.
380   UINT16  RuntimeSegment;               ///< The segment where the OpROM can be relocated to. If this value is 0x0000, this
381                                         ///< means that the relocation of this run time code is not supported.
382                                         ///< Inconsistent with specification here:
383                                         ///< The member's name "OpromDestinationSegment" [defined in Intel Framework Compatibility Support Module Specification / 0.97 version]
384                                         ///< has been changed to "RuntimeSegment" since keeping backward compatible.
385 
386 } EFI_DISPATCH_OPROM_TABLE;
387 
388 ///
389 /// EFI_TO_COMPATIBILITY16_INIT_TABLE
390 ///
391 typedef struct {
392   ///
393   /// Starting address of memory under 1 MB. The ending address is assumed to be 640 KB or 0x9FFFF.
394   ///
395   UINT32                            BiosLessThan1MB;
396 
397   ///
398   /// The starting address of the high memory block.
399   ///
400   UINT32                            HiPmmMemory;
401 
402   ///
403   /// The length of high memory block.
404   ///
405   UINT32                            HiPmmMemorySizeInBytes;
406 
407   ///
408   /// The segment of the reverse thunk call code.
409   ///
410   UINT16                            ReverseThunkCallSegment;
411 
412   ///
413   /// The offset of the reverse thunk call code.
414   ///
415   UINT16                            ReverseThunkCallOffset;
416 
417   ///
418   /// The number of E820 entries copied to the Compatibility16 BIOS.
419   ///
420   UINT32                            NumberE820Entries;
421 
422   ///
423   /// The amount of usable memory above 1 MB, e.g., E820 type 1 memory.
424   ///
425   UINT32                            OsMemoryAbove1Mb;
426 
427   ///
428   /// The start of thunk code in main memory. Memory cannot be used by BIOS or PMM.
429   ///
430   UINT32                            ThunkStart;
431 
432   ///
433   /// The size of the thunk code.
434   ///
435   UINT32                            ThunkSizeInBytes;
436 
437   ///
438   /// Starting address of memory under 1 MB.
439   ///
440   UINT32                            LowPmmMemory;
441 
442   ///
443   /// The length of low Memory block.
444   ///
445   UINT32                            LowPmmMemorySizeInBytes;
446 } EFI_TO_COMPATIBILITY16_INIT_TABLE;
447 
448 ///
449 /// DEVICE_PRODUCER_SERIAL.
450 ///
451 typedef struct {
452   UINT16                            Address;    ///< I/O address assigned to the serial port.
453   UINT8                             Irq;        ///< IRQ assigned to the serial port.
454   SERIAL_MODE                       Mode;       ///< Mode of serial port. Values are defined below.
455 } DEVICE_PRODUCER_SERIAL;
456 
457 ///
458 /// DEVICE_PRODUCER_SERIAL's modes.
459 ///@{
460 #define DEVICE_SERIAL_MODE_NORMAL               0x00
461 #define DEVICE_SERIAL_MODE_IRDA                 0x01
462 #define DEVICE_SERIAL_MODE_ASK_IR               0x02
463 #define DEVICE_SERIAL_MODE_DUPLEX_HALF          0x00
464 #define DEVICE_SERIAL_MODE_DUPLEX_FULL          0x10
465 ///@)
466 
467 ///
468 /// DEVICE_PRODUCER_PARALLEL.
469 ///
470 typedef struct {
471   UINT16                            Address;  ///< I/O address assigned to the parallel port.
472   UINT8                             Irq;      ///< IRQ assigned to the parallel port.
473   UINT8                             Dma;      ///< DMA assigned to the parallel port.
474   PARALLEL_MODE                     Mode;     ///< Mode of the parallel port. Values are defined below.
475 } DEVICE_PRODUCER_PARALLEL;
476 
477 ///
478 /// DEVICE_PRODUCER_PARALLEL's modes.
479 ///@{
480 #define DEVICE_PARALLEL_MODE_MODE_OUTPUT_ONLY   0x00
481 #define DEVICE_PARALLEL_MODE_MODE_BIDIRECTIONAL 0x01
482 #define DEVICE_PARALLEL_MODE_MODE_EPP           0x02
483 #define DEVICE_PARALLEL_MODE_MODE_ECP           0x03
484 ///@}
485 
486 ///
487 /// DEVICE_PRODUCER_FLOPPY
488 ///
489 typedef struct {
490   UINT16                            Address;          ///< I/O address assigned to the floppy.
491   UINT8                             Irq;              ///< IRQ assigned to the floppy.
492   UINT8                             Dma;              ///< DMA assigned to the floppy.
493   UINT8                             NumberOfFloppy;   ///< Number of floppies in the system.
494 } DEVICE_PRODUCER_FLOPPY;
495 
496 ///
497 /// LEGACY_DEVICE_FLAGS
498 ///
499 typedef struct {
500   UINT32                            A20Kybd : 1;      ///< A20 controller by keyboard controller.
501   UINT32                            A20Port90 : 1;    ///< A20 controlled by port 0x92.
502   UINT32                            Reserved : 30;    ///< Reserved for future usage.
503 } LEGACY_DEVICE_FLAGS;
504 
505 ///
506 /// DEVICE_PRODUCER_DATA_HEADER
507 ///
508 typedef struct {
509   DEVICE_PRODUCER_SERIAL            Serial[4];      ///< Data for serial port x. Type DEVICE_PRODUCER_SERIAL is defined below.
510   DEVICE_PRODUCER_PARALLEL          Parallel[3];    ///< Data for parallel port x. Type DEVICE_PRODUCER_PARALLEL is defined below.
511   DEVICE_PRODUCER_FLOPPY            Floppy;         ///< Data for floppy. Type DEVICE_PRODUCER_FLOPPY is defined below.
512   UINT8                             MousePresent;   ///< Flag to indicate if mouse is present.
513   LEGACY_DEVICE_FLAGS               Flags;          ///< Miscellaneous Boolean state information passed to CSM.
514 } DEVICE_PRODUCER_DATA_HEADER;
515 
516 ///
517 /// ATAPI_IDENTIFY
518 ///
519 typedef struct {
520   UINT16                            Raw[256];     ///< Raw data from the IDE IdentifyDrive command.
521 } ATAPI_IDENTIFY;
522 
523 ///
524 /// HDD_INFO
525 ///
526 typedef struct {
527   ///
528   /// Status of IDE device. Values are defined below. There is one HDD_INFO structure
529   /// per IDE controller. The IdentifyDrive is per drive. Index 0 is master and index
530   /// 1 is slave.
531   ///
532   UINT16                            Status;
533 
534   ///
535   /// PCI bus of IDE controller.
536   ///
537   UINT32                            Bus;
538 
539   ///
540   /// PCI device of IDE controller.
541   ///
542   UINT32                            Device;
543 
544   ///
545   /// PCI function of IDE controller.
546   ///
547   UINT32                            Function;
548 
549   ///
550   /// Command ports base address.
551   ///
552   UINT16                            CommandBaseAddress;
553 
554   ///
555   /// Control ports base address.
556   ///
557   UINT16                            ControlBaseAddress;
558 
559   ///
560   /// Bus master address.
561   ///
562   UINT16                            BusMasterAddress;
563 
564   UINT8                             HddIrq;
565 
566   ///
567   /// Data that identifies the drive data; one per possible attached drive.
568   ///
569   ATAPI_IDENTIFY                    IdentifyDrive[2];
570 } HDD_INFO;
571 
572 ///
573 /// HDD_INFO status bits
574 ///
575 #define HDD_PRIMARY               0x01
576 #define HDD_SECONDARY             0x02
577 #define HDD_MASTER_ATAPI_CDROM    0x04
578 #define HDD_SLAVE_ATAPI_CDROM     0x08
579 #define HDD_MASTER_IDE            0x20
580 #define HDD_SLAVE_IDE             0x40
581 #define HDD_MASTER_ATAPI_ZIPDISK  0x10
582 #define HDD_SLAVE_ATAPI_ZIPDISK   0x80
583 
584 ///
585 /// BBS_STATUS_FLAGS;\.
586 ///
587 typedef struct {
588   UINT16                            OldPosition : 4;    ///< Prior priority.
589   UINT16                            Reserved1 : 4;      ///< Reserved for future use.
590   UINT16                            Enabled : 1;        ///< If 0, ignore this entry.
591   UINT16                            Failed : 1;         ///< 0 = Not known if boot failure occurred.
592                                                         ///< 1 = Boot attempted failed.
593 
594   ///
595   /// State of media present.
596   ///   00 = No bootable media is present in the device.
597   ///   01 = Unknown if a bootable media present.
598   ///   10 = Media is present and appears bootable.
599   ///   11 = Reserved.
600   ///
601   UINT16                            MediaPresent : 2;
602   UINT16                            Reserved2 : 4;      ///< Reserved for future use.
603 } BBS_STATUS_FLAGS;
604 
605 ///
606 /// BBS_TABLE, device type values & boot priority values.
607 ///
608 typedef struct {
609   ///
610   /// The boot priority for this boot device. Values are defined below.
611   ///
612   UINT16                            BootPriority;
613 
614   ///
615   /// The PCI bus for this boot device.
616   ///
617   UINT32                            Bus;
618 
619   ///
620   /// The PCI device for this boot device.
621   ///
622   UINT32                            Device;
623 
624   ///
625   /// The PCI function for the boot device.
626   ///
627   UINT32                            Function;
628 
629   ///
630   /// The PCI class for this boot device.
631   ///
632   UINT8                             Class;
633 
634   ///
635   /// The PCI Subclass for this boot device.
636   ///
637   UINT8                             SubClass;
638 
639   ///
640   /// Segment:offset address of an ASCIIZ description string describing the manufacturer.
641   ///
642   UINT16                            MfgStringOffset;
643 
644   ///
645   /// Segment:offset address of an ASCIIZ description string describing the manufacturer.
646   ///
647   UINT16                            MfgStringSegment;
648 
649   ///
650   /// BBS device type. BBS device types are defined below.
651   ///
652   UINT16                            DeviceType;
653 
654   ///
655   /// Status of this boot device. Type BBS_STATUS_FLAGS is defined below.
656   ///
657   BBS_STATUS_FLAGS                  StatusFlags;
658 
659   ///
660   /// Segment:Offset address of boot loader for IPL devices or install INT13 handler for
661   /// BCV devices.
662   ///
663   UINT16                            BootHandlerOffset;
664 
665   ///
666   /// Segment:Offset address of boot loader for IPL devices or install INT13 handler for
667   /// BCV devices.
668   ///
669   UINT16                            BootHandlerSegment;
670 
671   ///
672   /// Segment:offset address of an ASCIIZ description string describing this device.
673   ///
674   UINT16                            DescStringOffset;
675 
676   ///
677   /// Segment:offset address of an ASCIIZ description string describing this device.
678   ///
679   UINT16                            DescStringSegment;
680 
681   ///
682   /// Reserved.
683   ///
684   UINT32                            InitPerReserved;
685 
686   ///
687   /// The use of these fields is IBV dependent. They can be used to flag that an OpROM
688   /// has hooked the specified IRQ. The OpROM may be BBS compliant as some SCSI
689   /// BBS-compliant OpROMs also hook IRQ vectors in order to run their BIOS Setup
690   ///
691   UINT32                            AdditionalIrq13Handler;
692 
693   ///
694   /// The use of these fields is IBV dependent. They can be used to flag that an OpROM
695   /// has hooked the specified IRQ. The OpROM may be BBS compliant as some SCSI
696   /// BBS-compliant OpROMs also hook IRQ vectors in order to run their BIOS Setup
697   ///
698   UINT32                            AdditionalIrq18Handler;
699 
700   ///
701   /// The use of these fields is IBV dependent. They can be used to flag that an OpROM
702   /// has hooked the specified IRQ. The OpROM may be BBS compliant as some SCSI
703   /// BBS-compliant OpROMs also hook IRQ vectors in order to run their BIOS Setup
704   ///
705   UINT32                            AdditionalIrq19Handler;
706 
707   ///
708   /// The use of these fields is IBV dependent. They can be used to flag that an OpROM
709   /// has hooked the specified IRQ. The OpROM may be BBS compliant as some SCSI
710   /// BBS-compliant OpROMs also hook IRQ vectors in order to run their BIOS Setup
711   ///
712   UINT32                            AdditionalIrq40Handler;
713   UINT8                             AssignedDriveNumber;
714   UINT32                            AdditionalIrq41Handler;
715   UINT32                            AdditionalIrq46Handler;
716   UINT32                            IBV1;
717   UINT32                            IBV2;
718 } BBS_TABLE;
719 
720 ///
721 /// BBS device type values
722 ///@{
723 #define BBS_FLOPPY              0x01
724 #define BBS_HARDDISK            0x02
725 #define BBS_CDROM               0x03
726 #define BBS_PCMCIA              0x04
727 #define BBS_USB                 0x05
728 #define BBS_EMBED_NETWORK       0x06
729 #define BBS_BEV_DEVICE          0x80
730 #define BBS_UNKNOWN             0xff
731 ///@}
732 
733 ///
734 /// BBS boot priority values
735 ///@{
736 #define BBS_DO_NOT_BOOT_FROM    0xFFFC
737 #define BBS_LOWEST_PRIORITY     0xFFFD
738 #define BBS_UNPRIORITIZED_ENTRY 0xFFFE
739 #define BBS_IGNORE_ENTRY        0xFFFF
740 ///@}
741 
742 ///
743 /// SMM_ATTRIBUTES
744 ///
745 typedef struct {
746   ///
747   /// Access mechanism used to generate the soft SMI. Defined types are below. The other
748   /// values are reserved for future usage.
749   ///
750   UINT16                            Type : 3;
751 
752   ///
753   /// The size of "port" in bits. Defined values are below.
754   ///
755   UINT16                            PortGranularity : 3;
756 
757   ///
758   /// The size of data in bits. Defined values are below.
759   ///
760   UINT16                            DataGranularity : 3;
761 
762   ///
763   /// Reserved for future use.
764   ///
765   UINT16                            Reserved : 7;
766 } SMM_ATTRIBUTES;
767 
768 ///
769 /// SMM_ATTRIBUTES type values.
770 ///@{
771 #define STANDARD_IO       0x00
772 #define STANDARD_MEMORY   0x01
773 ///@}
774 
775 ///
776 /// SMM_ATTRIBUTES port size constants.
777 ///@{
778 #define PORT_SIZE_8       0x00
779 #define PORT_SIZE_16      0x01
780 #define PORT_SIZE_32      0x02
781 #define PORT_SIZE_64      0x03
782 ///@}
783 
784 ///
785 /// SMM_ATTRIBUTES data size constants.
786 ///@{
787 #define DATA_SIZE_8       0x00
788 #define DATA_SIZE_16      0x01
789 #define DATA_SIZE_32      0x02
790 #define DATA_SIZE_64      0x03
791 ///@}
792 
793 ///
794 /// SMM_FUNCTION & relating constants.
795 ///
796 typedef struct {
797   UINT16                            Function : 15;
798   UINT16                            Owner : 1;
799 } SMM_FUNCTION;
800 
801 ///
802 /// SMM_FUNCTION Function constants.
803 ///@{
804 #define INT15_D042        0x0000
805 #define GET_USB_BOOT_INFO 0x0001
806 #define DMI_PNP_50_57     0x0002
807 ///@}
808 
809 ///
810 /// SMM_FUNCTION Owner constants.
811 ///@{
812 #define STANDARD_OWNER    0x0
813 #define OEM_OWNER         0x1
814 ///@}
815 
816 ///
817 /// This structure assumes both port and data sizes are 1. SmmAttribute must be
818 /// properly to reflect that assumption.
819 ///
820 typedef struct {
821   ///
822   /// Describes the access mechanism, SmmPort, and SmmData sizes. Type
823   /// SMM_ATTRIBUTES is defined below.
824   ///
825   SMM_ATTRIBUTES                    SmmAttributes;
826 
827   ///
828   /// Function Soft SMI is to perform. Type SMM_FUNCTION is defined below.
829   ///
830   SMM_FUNCTION                      SmmFunction;
831 
832   ///
833   /// SmmPort size depends upon SmmAttributes and ranges from2 bytes to 16 bytes.
834   ///
835   UINT8                             SmmPort;
836 
837   ///
838   /// SmmData size depends upon SmmAttributes and ranges from2 bytes to 16 bytes.
839   ///
840   UINT8                             SmmData;
841 } SMM_ENTRY;
842 
843 ///
844 /// SMM_TABLE
845 ///
846 typedef struct {
847   UINT16                            NumSmmEntries;    ///< Number of entries represented by SmmEntry.
848   SMM_ENTRY                         SmmEntry;         ///< One entry per function. Type SMM_ENTRY is defined below.
849 } SMM_TABLE;
850 
851 ///
852 /// UDC_ATTRIBUTES
853 ///
854 typedef struct {
855   ///
856   /// This bit set indicates that the ServiceAreaData is valid.
857   ///
858   UINT8                             DirectoryServiceValidity : 1;
859 
860   ///
861   /// This bit set indicates to use the Reserve Area Boot Code Address (RACBA) only if
862   /// DirectoryServiceValidity is 0.
863   ///
864   UINT8                             RabcaUsedFlag : 1;
865 
866   ///
867   /// This bit set indicates to execute hard disk diagnostics.
868   ///
869   UINT8                             ExecuteHddDiagnosticsFlag : 1;
870 
871   ///
872   /// Reserved for future use. Set to 0.
873   ///
874   UINT8                             Reserved : 5;
875 } UDC_ATTRIBUTES;
876 
877 ///
878 /// UD_TABLE
879 ///
880 typedef struct {
881   ///
882   /// This field contains the bit-mapped attributes of the PARTIES information. Type
883   /// UDC_ATTRIBUTES is defined below.
884   ///
885   UDC_ATTRIBUTES                    Attributes;
886 
887   ///
888   /// This field contains the zero-based device on which the selected
889   /// ServiceDataArea is present. It is 0 for master and 1 for the slave device.
890   ///
891   UINT8                             DeviceNumber;
892 
893   ///
894   /// This field contains the zero-based index into the BbsTable for the parent device.
895   /// This index allows the user to reference the parent device information such as PCI
896   /// bus, device function.
897   ///
898   UINT8                             BbsTableEntryNumberForParentDevice;
899 
900   ///
901   /// This field contains the zero-based index into the BbsTable for the boot entry.
902   ///
903   UINT8                             BbsTableEntryNumberForBoot;
904 
905   ///
906   /// This field contains the zero-based index into the BbsTable for the HDD diagnostics entry.
907   ///
908   UINT8                             BbsTableEntryNumberForHddDiag;
909 
910   ///
911   /// The raw Beer data.
912   ///
913   UINT8                             BeerData[128];
914 
915   ///
916   /// The raw data of selected service area.
917   ///
918   UINT8                             ServiceAreaData[64];
919 } UD_TABLE;
920 
921 #define EFI_TO_LEGACY_MAJOR_VERSION 0x02
922 #define EFI_TO_LEGACY_MINOR_VERSION 0x00
923 #define MAX_IDE_CONTROLLER          8
924 
925 ///
926 /// EFI_TO_COMPATIBILITY16_BOOT_TABLE
927 ///
928 typedef struct {
929   UINT16                            MajorVersion;                 ///< The EfiCompatibility major version number.
930   UINT16                            MinorVersion;                 ///< The EfiCompatibility minor version number.
931   UINT32                            AcpiTable;                    ///< The location of the RSDT ACPI table. < 4G range.
932   UINT32                            SmbiosTable;                  ///< The location of the SMBIOS table in EFI memory. < 4G range.
933   UINT32                            SmbiosTableLength;
934   //
935   // Legacy SIO state
936   //
937   DEVICE_PRODUCER_DATA_HEADER       SioData;                      ///< Standard traditional device information.
938   UINT16                            DevicePathType;               ///< The default boot type.
939   UINT16                            PciIrqMask;                   ///< Mask of which IRQs have been assigned to PCI.
940   UINT32                            NumberE820Entries;            ///< Number of E820 entries. The number can change from the
941                                                                   ///< Compatibility16InitializeYourself() function.
942   //
943   // Controller & Drive Identify[2] per controller information
944   //
945   HDD_INFO                          HddInfo[MAX_IDE_CONTROLLER];  ///< Hard disk drive information, including raw Identify Drive data.
946   UINT32                            NumberBbsEntries;             ///< Number of entries in the BBS table
947   UINT32                            BbsTable;                     ///< A pointer to the BBS table. Type BBS_TABLE is defined below.
948   UINT32                            SmmTable;                     ///< A pointer to the SMM table. Type SMM_TABLE is defined below.
949   UINT32                            OsMemoryAbove1Mb;             ///< The amount of usable memory above 1 MB, i.e. E820 type 1 memory. This value can
950                                                                   ///< differ from the value in EFI_TO_COMPATIBILITY16_INIT_TABLE as more
951                                                                   ///< memory may have been discovered.
952   UINT32                            UnconventionalDeviceTable;    ///< Information to boot off an unconventional device like a PARTIES partition. Type
953                                                                   ///< UD_TABLE is defined below.
954 } EFI_TO_COMPATIBILITY16_BOOT_TABLE;
955 
956 ///
957 /// EFI_LEGACY_INSTALL_PCI_HANDLER
958 ///
959 typedef struct {
960   UINT8                             PciBus;             ///< The PCI bus of the device.
961   UINT8                             PciDeviceFun;       ///< The PCI device in bits 7:3 and function in bits 2:0.
962   UINT8                             PciSegment;         ///< The PCI segment of the device.
963   UINT8                             PciClass;           ///< The PCI class code of the device.
964   UINT8                             PciSubclass;        ///< The PCI subclass code of the device.
965   UINT8                             PciInterface;       ///< The PCI interface code of the device.
966   //
967   // Primary section
968   //
969   UINT8                             PrimaryIrq;         ///< The primary device IRQ.
970   UINT8                             PrimaryReserved;    ///< Reserved.
971   UINT16                            PrimaryControl;     ///< The primary device control I/O base.
972   UINT16                            PrimaryBase;        ///< The primary device I/O base.
973   UINT16                            PrimaryBusMaster;   ///< The primary device bus master I/O base.
974   //
975   // Secondary Section
976   //
977   UINT8                             SecondaryIrq;       ///< The secondary device IRQ.
978   UINT8                             SecondaryReserved;  ///< Reserved.
979   UINT16                            SecondaryControl;   ///< The secondary device control I/O base.
980   UINT16                            SecondaryBase;      ///< The secondary device I/O base.
981   UINT16                            SecondaryBusMaster; ///< The secondary device bus master I/O base.
982 } EFI_LEGACY_INSTALL_PCI_HANDLER;
983 
984 //
985 // Restore default pack value
986 //
987 #pragma pack()
988 
989 #define EFI_LEGACY_BIOS_PROTOCOL_GUID \
990   { \
991     0xdb9a1e3d, 0x45cb, 0x4abb, {0x85, 0x3b, 0xe5, 0x38, 0x7f, 0xdb, 0x2e, 0x2d } \
992   }
993 
994 typedef struct _EFI_LEGACY_BIOS_PROTOCOL EFI_LEGACY_BIOS_PROTOCOL;
995 
996 ///
997 /// Flags returned by CheckPciRom().
998 ///
999 #define NO_ROM            0x00
1000 #define ROM_FOUND         0x01
1001 #define VALID_LEGACY_ROM  0x02
1002 #define ROM_WITH_CONFIG   0x04     ///< Not defined in the Framework CSM Specification.
1003 
1004 ///
1005 /// The following macros do not appear in the Framework CSM Specification and
1006 /// are kept for backward compatibility only.  They convert 32-bit address (_Adr)
1007 /// to Segment:Offset 16-bit form.
1008 ///
1009 ///@{
1010 #define EFI_SEGMENT(_Adr)     (UINT16) ((UINT16) (((UINTN) (_Adr)) >> 4) & 0xf000)
1011 #define EFI_OFFSET(_Adr)      (UINT16) (((UINT16) ((UINTN) (_Adr))) & 0xffff)
1012 ///@}
1013 
1014 #define CARRY_FLAG            0x01
1015 
1016 ///
1017 /// EFI_EFLAGS_REG
1018 ///
1019 typedef struct {
1020   UINT32 CF:1;
1021   UINT32 Reserved1:1;
1022   UINT32 PF:1;
1023   UINT32 Reserved2:1;
1024   UINT32 AF:1;
1025   UINT32 Reserved3:1;
1026   UINT32 ZF:1;
1027   UINT32 SF:1;
1028   UINT32 TF:1;
1029   UINT32 IF:1;
1030   UINT32 DF:1;
1031   UINT32 OF:1;
1032   UINT32 IOPL:2;
1033   UINT32 NT:1;
1034   UINT32 Reserved4:2;
1035   UINT32 VM:1;
1036   UINT32 Reserved5:14;
1037 } EFI_EFLAGS_REG;
1038 
1039 ///
1040 /// EFI_DWORD_REGS
1041 ///
1042 typedef struct {
1043     UINT32           EAX;
1044     UINT32           EBX;
1045     UINT32           ECX;
1046     UINT32           EDX;
1047     UINT32           ESI;
1048     UINT32           EDI;
1049     EFI_EFLAGS_REG   EFlags;
1050     UINT16           ES;
1051     UINT16           CS;
1052     UINT16           SS;
1053     UINT16           DS;
1054     UINT16           FS;
1055     UINT16           GS;
1056     UINT32           EBP;
1057     UINT32           ESP;
1058 } EFI_DWORD_REGS;
1059 
1060 ///
1061 /// EFI_FLAGS_REG
1062 ///
1063 typedef struct {
1064   UINT16     CF:1;
1065   UINT16     Reserved1:1;
1066   UINT16     PF:1;
1067   UINT16     Reserved2:1;
1068   UINT16     AF:1;
1069   UINT16     Reserved3:1;
1070   UINT16     ZF:1;
1071   UINT16     SF:1;
1072   UINT16     TF:1;
1073   UINT16     IF:1;
1074   UINT16     DF:1;
1075   UINT16     OF:1;
1076   UINT16     IOPL:2;
1077   UINT16     NT:1;
1078   UINT16     Reserved4:1;
1079 } EFI_FLAGS_REG;
1080 
1081 ///
1082 /// EFI_WORD_REGS
1083 ///
1084 typedef struct {
1085     UINT16           AX;
1086     UINT16           ReservedAX;
1087     UINT16           BX;
1088     UINT16           ReservedBX;
1089     UINT16           CX;
1090     UINT16           ReservedCX;
1091     UINT16           DX;
1092     UINT16           ReservedDX;
1093     UINT16           SI;
1094     UINT16           ReservedSI;
1095     UINT16           DI;
1096     UINT16           ReservedDI;
1097     EFI_FLAGS_REG    Flags;
1098     UINT16           ReservedFlags;
1099     UINT16           ES;
1100     UINT16           CS;
1101     UINT16           SS;
1102     UINT16           DS;
1103     UINT16           FS;
1104     UINT16           GS;
1105     UINT16           BP;
1106     UINT16           ReservedBP;
1107     UINT16           SP;
1108     UINT16           ReservedSP;
1109 } EFI_WORD_REGS;
1110 
1111 ///
1112 /// EFI_BYTE_REGS
1113 ///
1114 typedef struct {
1115     UINT8   AL, AH;
1116     UINT16  ReservedAX;
1117     UINT8   BL, BH;
1118     UINT16  ReservedBX;
1119     UINT8   CL, CH;
1120     UINT16  ReservedCX;
1121     UINT8   DL, DH;
1122     UINT16  ReservedDX;
1123 } EFI_BYTE_REGS;
1124 
1125 ///
1126 /// EFI_IA32_REGISTER_SET
1127 ///
1128 typedef union {
1129   EFI_DWORD_REGS  E;
1130   EFI_WORD_REGS   X;
1131   EFI_BYTE_REGS   H;
1132 } EFI_IA32_REGISTER_SET;
1133 
1134 /**
1135   Thunk to 16-bit real mode and execute a software interrupt with a vector
1136   of BiosInt. Regs will contain the 16-bit register context on entry and
1137   exit.
1138 
1139   @param[in]     This      The protocol instance pointer.
1140   @param[in]     BiosInt   The processor interrupt vector to invoke.
1141   @param[in,out] Reg       Register contexted passed into (and returned) from thunk to
1142                            16-bit mode.
1143 
1144   @retval TRUE                Thunk completed with no BIOS errors in the target code. See Regs for status.
1145   @retval FALSE                  There was a BIOS error in the target code.
1146 **/
1147 typedef
1148 BOOLEAN
1149 (EFIAPI *EFI_LEGACY_BIOS_INT86)(
1150   IN     EFI_LEGACY_BIOS_PROTOCOL  *This,
1151   IN     UINT8                     BiosInt,
1152   IN OUT EFI_IA32_REGISTER_SET     *Regs
1153   );
1154 
1155 /**
1156   Thunk to 16-bit real mode and call Segment:Offset. Regs will contain the
1157   16-bit register context on entry and exit. Arguments can be passed on
1158   the Stack argument
1159 
1160   @param[in] This        The protocol instance pointer.
1161   @param[in] Segment     The segemnt of 16-bit mode call.
1162   @param[in] Offset      The offset of 16-bit mdoe call.
1163   @param[in] Reg         Register contexted passed into (and returned) from thunk to
1164                          16-bit mode.
1165   @param[in] Stack       The caller allocated stack used to pass arguments.
1166   @param[in] StackSize   The size of Stack in bytes.
1167 
1168   @retval FALSE                 Thunk completed with no BIOS errors in the target code.                                See Regs for status.  @retval TRUE                  There was a BIOS error in the target code.
1169 **/
1170 typedef
1171 BOOLEAN
1172 (EFIAPI *EFI_LEGACY_BIOS_FARCALL86)(
1173   IN EFI_LEGACY_BIOS_PROTOCOL  *This,
1174   IN UINT16                    Segment,
1175   IN UINT16                    Offset,
1176   IN EFI_IA32_REGISTER_SET     *Regs,
1177   IN VOID                      *Stack,
1178   IN UINTN                     StackSize
1179   );
1180 
1181 /**
1182   Test to see if a legacy PCI ROM exists for this device. Optionally return
1183   the Legacy ROM instance for this PCI device.
1184 
1185   @param[in]  This        The protocol instance pointer.
1186   @param[in]  PciHandle   The PCI PC-AT OPROM from this devices ROM BAR will be loaded
1187   @param[out] RomImage    Return the legacy PCI ROM for this device.
1188   @param[out] RomSize     The size of ROM Image.
1189   @param[out] Flags       Indicates if ROM found and if PC-AT. Multiple bits can be set as follows:
1190                             - 00 = No ROM.
1191                             - 01 = ROM Found.
1192                             - 02 = ROM is a valid legacy ROM.
1193 
1194   @retval EFI_SUCCESS       The Legacy Option ROM available for this device
1195   @retval EFI_UNSUPPORTED   The Legacy Option ROM is not supported.
1196 
1197 **/
1198 typedef
1199 EFI_STATUS
1200 (EFIAPI *EFI_LEGACY_BIOS_CHECK_ROM)(
1201   IN  EFI_LEGACY_BIOS_PROTOCOL  *This,
1202   IN  EFI_HANDLE                PciHandle,
1203   OUT VOID                      **RomImage, OPTIONAL
1204   OUT UINTN                     *RomSize, OPTIONAL
1205   OUT UINTN                     *Flags
1206   );
1207 
1208 /**
1209   Load a legacy PC-AT OPROM on the PciHandle device. Return information
1210   about how many disks were added by the OPROM and the shadow address and
1211   size. DiskStart & DiskEnd are INT 13h drive letters. Thus 0x80 is C:
1212 
1213   @param[in]  This               The protocol instance pointer.
1214   @param[in]  PciHandle          The PCI PC-AT OPROM from this devices ROM BAR will be loaded.
1215                                  This value is NULL if RomImage is non-NULL. This is the normal
1216                                  case.
1217   @param[in]  RomImage           A PCI PC-AT ROM image. This argument is non-NULL if there is
1218                                  no hardware associated with the ROM and thus no PciHandle,
1219                                  otherwise is must be NULL.
1220                                  Example is PXE base code.
1221   @param[out] Flags              The type of ROM discovered. Multiple bits can be set, as follows:
1222                                    - 00 = No ROM.
1223                                    - 01 = ROM found.
1224                                    - 02 = ROM is a valid legacy ROM.
1225   @param[out] DiskStart          The disk number of first device hooked by the ROM. If DiskStart
1226                                  is the same as DiskEnd no disked were hooked.
1227   @param[out] DiskEnd            disk number of the last device hooked by the ROM.
1228   @param[out] RomShadowAddress   Shadow address of PC-AT ROM.
1229   @param[out] RomShadowSize      Size of RomShadowAddress in bytes.
1230 
1231   @retval EFI_SUCCESS             Thunk completed, see Regs for status.
1232   @retval EFI_INVALID_PARAMETER   PciHandle not found
1233 
1234 **/
1235 typedef
1236 EFI_STATUS
1237 (EFIAPI *EFI_LEGACY_BIOS_INSTALL_ROM)(
1238   IN  EFI_LEGACY_BIOS_PROTOCOL  *This,
1239   IN  EFI_HANDLE                PciHandle,
1240   IN  VOID                      **RomImage,
1241   OUT UINTN                     *Flags,
1242   OUT UINT8                     *DiskStart, OPTIONAL
1243   OUT UINT8                     *DiskEnd, OPTIONAL
1244   OUT VOID                      **RomShadowAddress, OPTIONAL
1245   OUT UINT32                    *ShadowedRomSize OPTIONAL
1246   );
1247 
1248 /**
1249   This function attempts to traditionally boot the specified BootOption. If the EFI context has
1250   been compromised, this function will not return. This procedure is not used for loading an EFI-aware
1251   OS off a traditional device. The following actions occur:
1252   - Get EFI SMBIOS data structures, convert them to a traditional format, and copy to
1253     Compatibility16.
1254   - Get a pointer to ACPI data structures and copy the Compatibility16 RSD PTR to F0000 block.
1255   - Find the traditional SMI handler from a firmware volume and register the traditional SMI
1256     handler with the EFI SMI handler.
1257   - Build onboard IDE information and pass this information to the Compatibility16 code.
1258   - Make sure all PCI Interrupt Line registers are programmed to match 8259.
1259   - Reconfigure SIO devices from EFI mode (polled) into traditional mode (interrupt driven).
1260   - Shadow all PCI ROMs.
1261   - Set up BDA and EBDA standard areas before the legacy boot.
1262   - Construct the Compatibility16 boot memory map and pass it to the Compatibility16 code.
1263   - Invoke the Compatibility16 table function Compatibility16PrepareToBoot(). This
1264     invocation causes a thunk into the Compatibility16 code, which sets all appropriate internal
1265     data structures. The boot device list is a parameter.
1266   - Invoke the Compatibility16 Table function Compatibility16Boot(). This invocation
1267     causes a thunk into the Compatibility16 code, which does an INT19.
1268   - If the Compatibility16Boot() function returns, then the boot failed in a graceful
1269     manner--meaning that the EFI code is still valid. An ungraceful boot failure causes a reset because the state
1270     of EFI code is unknown.
1271 
1272   @param[in] This             The protocol instance pointer.
1273   @param[in] BootOption       The EFI Device Path from BootXXXX variable.
1274   @param[in] LoadOptionSize   The size of LoadOption in size.
1275   @param[in] LoadOption       LThe oadOption from BootXXXX variable.
1276 
1277   @retval EFI_DEVICE_ERROR      Failed to boot from any boot device and memory is uncorrupted.                                Note: This function normally does not returns. It will either boot the                                OS or reset the system if memory has been "corrupted" by loading                                a boot sector and passing control to it.
1278 **/
1279 typedef
1280 EFI_STATUS
1281 (EFIAPI *EFI_LEGACY_BIOS_BOOT)(
1282   IN EFI_LEGACY_BIOS_PROTOCOL  *This,
1283   IN BBS_BBS_DEVICE_PATH       *BootOption,
1284   IN UINT32                    LoadOptionsSize,
1285   IN VOID                      *LoadOptions
1286   );
1287 
1288 /**
1289   This function takes the Leds input parameter and sets/resets the BDA accordingly.
1290   Leds is also passed to Compatibility16 code, in case any special processing is required.
1291   This function is normally called from EFI Setup drivers that handle user-selectable
1292   keyboard options such as boot with NUM LOCK on/off. This function does not
1293   touch the keyboard or keyboard LEDs but only the BDA.
1294 
1295   @param[in] This   The protocol instance pointer.
1296   @param[in] Leds   The status of current Scroll, Num & Cap lock LEDS:
1297                       - Bit 0 is Scroll Lock 0 = Not locked.
1298                       - Bit 1 is Num Lock.
1299                       - Bit 2 is Caps Lock.
1300 
1301   @retval EFI_SUCCESS   The BDA was updated successfully.
1302 
1303 **/
1304 typedef
1305 EFI_STATUS
1306 (EFIAPI *EFI_LEGACY_BIOS_UPDATE_KEYBOARD_LED_STATUS)(
1307   IN EFI_LEGACY_BIOS_PROTOCOL  *This,
1308   IN UINT8                     Leds
1309   );
1310 
1311 /**
1312   Retrieve legacy BBS info and assign boot priority.
1313 
1314   @param[in]     This       The protocol instance pointer.
1315   @param[out]    HddCount   The number of HDD_INFO structures.
1316   @param[out]    HddInfo    Onboard IDE controller information.
1317   @param[out]    BbsCount   The number of BBS_TABLE structures.
1318   @param[in,out] BbsTable   Points to List of BBS_TABLE.
1319 
1320   @retval EFI_SUCCESS   Tables were returned.
1321 
1322 **/
1323 typedef
1324 EFI_STATUS
1325 (EFIAPI *EFI_LEGACY_BIOS_GET_BBS_INFO)(
1326   IN     EFI_LEGACY_BIOS_PROTOCOL  *This,
1327   OUT    UINT16                    *HddCount,
1328   OUT    HDD_INFO                  **HddInfo,
1329   OUT    UINT16                    *BbsCount,
1330   IN OUT BBS_TABLE                 **BbsTable
1331   );
1332 
1333 /**
1334   Assign drive number to legacy HDD drives prior to booting an EFI
1335   aware OS so the OS can access drives without an EFI driver.
1336 
1337   @param[in]  This       The protocol instance pointer.
1338   @param[out] BbsCount   The number of BBS_TABLE structures
1339   @param[out] BbsTable   List of BBS entries
1340 
1341   @retval EFI_SUCCESS   Drive numbers assigned.
1342 
1343 **/
1344 typedef
1345 EFI_STATUS
1346 (EFIAPI *EFI_LEGACY_BIOS_PREPARE_TO_BOOT_EFI)(
1347   IN  EFI_LEGACY_BIOS_PROTOCOL  *This,
1348   OUT UINT16                    *BbsCount,
1349   OUT BBS_TABLE                 **BbsTable
1350   );
1351 
1352 /**
1353   To boot from an unconventional device like parties and/or execute
1354   HDD diagnostics.
1355 
1356   @param[in]  This              The protocol instance pointer.
1357   @param[in]  Attributes        How to interpret the other input parameters.
1358   @param[in]  BbsEntry          The 0-based index into the BbsTable for the parent
1359                                 device.
1360   @param[in]  BeerData          A pointer to the 128 bytes of ram BEER data.
1361   @param[in]  ServiceAreaData   A pointer to the 64 bytes of raw Service Area data. The
1362                                 caller must provide a pointer to the specific Service
1363                                 Area and not the start all Service Areas.
1364 
1365   @retval EFI_INVALID_PARAMETER   If error. Does NOT return if no error.
1366 
1367 **/
1368 typedef
1369 EFI_STATUS
1370 (EFIAPI *EFI_LEGACY_BIOS_BOOT_UNCONVENTIONAL_DEVICE)(
1371   IN EFI_LEGACY_BIOS_PROTOCOL  *This,
1372   IN UDC_ATTRIBUTES            Attributes,
1373   IN UINTN                     BbsEntry,
1374   IN VOID                      *BeerData,
1375   IN VOID                      *ServiceAreaData
1376   );
1377 
1378 /**
1379   Shadow all legacy16 OPROMs that haven't been shadowed.
1380   Warning: Use this with caution. This routine disconnects all EFI
1381   drivers. If used externally, then  the caller must re-connect EFI
1382   drivers.
1383 
1384   @param[in]  This   The protocol instance pointer.
1385 
1386   @retval EFI_SUCCESS   OPROMs were shadowed.
1387 
1388 **/
1389 typedef
1390 EFI_STATUS
1391 (EFIAPI *EFI_LEGACY_BIOS_SHADOW_ALL_LEGACY_OPROMS)(
1392   IN EFI_LEGACY_BIOS_PROTOCOL  *This
1393   );
1394 
1395 /**
1396   Get a region from the LegacyBios for S3 usage.
1397 
1398   @param[in]  This                  The protocol instance pointer.
1399   @param[in]  LegacyMemorySize      The size of required region.
1400   @param[in]  Region                The region to use.
1401                                     00 = Either 0xE0000 or 0xF0000 block.
1402                                       - Bit0 = 1 0xF0000 block.
1403                                       - Bit1 = 1 0xE0000 block.
1404   @param[in]  Alignment             Address alignment. Bit mapped. The first non-zero
1405                                     bit from right is alignment.
1406   @param[out] LegacyMemoryAddress   The Region Assigned
1407 
1408   @retval EFI_SUCCESS           The Region was assigned.
1409   @retval EFI_ACCESS_DENIED     The function was previously invoked.
1410   @retval Other                 The Region was not assigned.
1411 
1412 **/
1413 typedef
1414 EFI_STATUS
1415 (EFIAPI *EFI_LEGACY_BIOS_GET_LEGACY_REGION)(
1416   IN  EFI_LEGACY_BIOS_PROTOCOL  *This,
1417   IN  UINTN                     LegacyMemorySize,
1418   IN  UINTN                     Region,
1419   IN  UINTN                     Alignment,
1420   OUT VOID                      **LegacyMemoryAddress
1421   );
1422 
1423 /**
1424   Get a region from the LegacyBios for Tiano usage. Can only be invoked once.
1425 
1426   @param[in]  This                        The protocol instance pointer.
1427   @param[in]  LegacyMemorySize            The size of data to copy.
1428   @param[in]  LegacyMemoryAddress         The Legacy Region destination address.
1429                                           Note: must be in region assigned by
1430                                           LegacyBiosGetLegacyRegion.
1431   @param[in]  LegacyMemorySourceAddress   The source of the data to copy.
1432 
1433   @retval EFI_SUCCESS           The Region assigned.
1434   @retval EFI_ACCESS_DENIED     Destination was outside an assigned region.
1435 
1436 **/
1437 typedef
1438 EFI_STATUS
1439 (EFIAPI *EFI_LEGACY_BIOS_COPY_LEGACY_REGION)(
1440   IN EFI_LEGACY_BIOS_PROTOCOL  *This,
1441   IN UINTN                     LegacyMemorySize,
1442   IN VOID                      *LegacyMemoryAddress,
1443   IN VOID                      *LegacyMemorySourceAddress
1444   );
1445 
1446 ///
1447 /// Abstracts the traditional BIOS from the rest of EFI. The LegacyBoot()
1448 /// member function allows the BDS to support booting a traditional OS.
1449 /// EFI thunks drivers that make EFI bindings for BIOS INT services use
1450 /// all the other member functions.
1451 ///
1452 struct _EFI_LEGACY_BIOS_PROTOCOL {
1453   ///
1454   /// Performs traditional software INT. See the Int86() function description.
1455   ///
1456   EFI_LEGACY_BIOS_INT86                       Int86;
1457 
1458   ///
1459   /// Performs a far call into Compatibility16 or traditional OpROM code.
1460   ///
1461   EFI_LEGACY_BIOS_FARCALL86                   FarCall86;
1462 
1463   ///
1464   /// Checks if a traditional OpROM exists for this device.
1465   ///
1466   EFI_LEGACY_BIOS_CHECK_ROM                   CheckPciRom;
1467 
1468   ///
1469   /// Loads a traditional OpROM in traditional OpROM address space.
1470   ///
1471   EFI_LEGACY_BIOS_INSTALL_ROM                 InstallPciRom;
1472 
1473   ///
1474   /// Boots a traditional OS.
1475   ///
1476   EFI_LEGACY_BIOS_BOOT                        LegacyBoot;
1477 
1478   ///
1479   /// Updates BDA to reflect the current EFI keyboard LED status.
1480   ///
1481   EFI_LEGACY_BIOS_UPDATE_KEYBOARD_LED_STATUS  UpdateKeyboardLedStatus;
1482 
1483   ///
1484   /// Allows an external agent, such as BIOS Setup, to get the BBS data.
1485   ///
1486   EFI_LEGACY_BIOS_GET_BBS_INFO                GetBbsInfo;
1487 
1488   ///
1489   /// Causes all legacy OpROMs to be shadowed.
1490   ///
1491   EFI_LEGACY_BIOS_SHADOW_ALL_LEGACY_OPROMS    ShadowAllLegacyOproms;
1492 
1493   ///
1494   /// Performs all actions prior to boot. Used when booting an EFI-aware OS
1495   /// rather than a legacy OS.
1496   ///
1497   EFI_LEGACY_BIOS_PREPARE_TO_BOOT_EFI         PrepareToBootEfi;
1498 
1499   ///
1500   /// Allows EFI to reserve an area in the 0xE0000 or 0xF0000 block.
1501   ///
1502   EFI_LEGACY_BIOS_GET_LEGACY_REGION           GetLegacyRegion;
1503 
1504   ///
1505   /// Allows EFI to copy data to the area specified by GetLegacyRegion.
1506   ///
1507   EFI_LEGACY_BIOS_COPY_LEGACY_REGION          CopyLegacyRegion;
1508 
1509   ///
1510   /// Allows the user to boot off an unconventional device such as a PARTIES partition.
1511   ///
1512   EFI_LEGACY_BIOS_BOOT_UNCONVENTIONAL_DEVICE  BootUnconventionalDevice;
1513 };
1514 
1515 //
1516 // Legacy BIOS needs to access memory in page 0 (0-4095), which is disabled if
1517 // NULL pointer detection feature is enabled. Following macro can be used to
1518 // enable/disable page 0 before/after accessing it.
1519 //
1520 #define ACCESS_PAGE0_CODE(statements)                           \
1521   do {                                                          \
1522     EFI_STATUS                            Status_;              \
1523     EFI_GCD_MEMORY_SPACE_DESCRIPTOR       Desc_;                \
1524                                                                 \
1525     Desc_.Attributes = 0;                                       \
1526     Status_ = gDS->GetMemorySpaceDescriptor (0, &Desc_);        \
1527     ASSERT_EFI_ERROR (Status_);                                 \
1528     if ((Desc_.Attributes & EFI_MEMORY_RP) != 0) {              \
1529       Status_ = gDS->SetMemorySpaceAttributes (                 \
1530                       0,                                        \
1531                       EFI_PAGES_TO_SIZE(1),                     \
1532                       Desc_.Attributes & ~(UINT64)EFI_MEMORY_RP \
1533                       );                                        \
1534       ASSERT_EFI_ERROR (Status_);                               \
1535     }                                                           \
1536                                                                 \
1537     {                                                           \
1538       statements;                                               \
1539     }                                                           \
1540                                                                 \
1541     if ((Desc_.Attributes & EFI_MEMORY_RP) != 0) {              \
1542       Status_ = gDS->SetMemorySpaceAttributes (                 \
1543                       0,                                        \
1544                       EFI_PAGES_TO_SIZE(1),                     \
1545                       Desc_.Attributes                          \
1546                       );                                        \
1547       ASSERT_EFI_ERROR (Status_);                               \
1548     }                                                           \
1549   } while (FALSE)
1550 
1551 extern EFI_GUID gEfiLegacyBiosProtocolGuid;
1552 
1553 #endif
1554