xref: /freebsd/share/man/man9/bios.9 (revision 0957b409)
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27.Dd August 9, 2005
28.Dt BIOS 9
29.Os
30.Sh NAME
31.Nm bios_sigsearch ,
32.Nm bios32_SDlookup ,
33.Nm bios32 ,
34.Nm bios_oem_strings
35.Nd interact with PC BIOS
36.Sh SYNOPSIS
37.In sys/param.h
38.In vm/vm.h
39.In vm/pmap.h
40.In machine/pc/bios.h
41.Ft uint32_t
42.Fn bios_sigsearch "uint32_t start" "u_char *sig" "int siglen" "int paralen" "int sigofs"
43.Ft int
44.Fn bios32_SDlookup "struct bios32_SDentry *ent"
45.Ft int
46.Fn bios32 "struct bios_regs *br" "u_int offset" "u_short segment"
47.Fn BIOS_PADDRTOVADDR "addr"
48.Fn BIOS_VADDRTOPADDR "addr"
49.Vt extern struct bios32_SDentry PCIbios ;
50.Vt extern struct SMBIOS_table SMBIOStable ;
51.Vt extern struct DMI_table DMItable ;
52.Ft int
53.Fn bios_oem_strings "struct bios_oem *oem" "u_char *buffer" "size_t maxlen"
54.Bd -literal
55struct bios_oem_signature {
56        char * anchor;          /* search anchor string in BIOS memory */
57        size_t offset;          /* offset from anchor (may be negative) */
58        size_t totlen;          /* total length of BIOS string to copy */
59};
60struct bios_oem_range {
61        u_int from;             /* shouldn't be below 0xe0000 */
62        u_int to;               /* shouldn't be above 0xfffff */
63};
64struct bios_oem {
65        struct bios_oem_range range;
66        struct bios_oem_signature signature[];
67};
68.Ed
69.Sh DESCRIPTION
70These functions provide a general-purpose interface for dealing with
71the BIOS functions and data encountered on x86 PC-architecture systems.
72.Bl -tag -width 20n
73.It Fn bios_sigsearch
74Searches the BIOS address space for a service signature, usually an
75uppercase ASCII sequence surrounded by underscores.
76The search begins at
77.Fa start ,
78or at the beginning of the BIOS if
79.Fa start
80is zero.
81.Fa siglen
82bytes of the BIOS image and
83.Fa sig
84are compared at
85.Fa sigofs
86bytes offset from the current location.
87If no match is found, the
88current location is incremented by
89.Fa paralen
90bytes and the search repeated.
91If the signature is found, its effective
92physical address is returned.
93If no signature is found, zero is returned.
94.It Fn bios_oem_strings
95Searches a given BIOS memory range for one or more strings,
96and composes a printable concatenation of those found.
97The routine expects a structure describing the BIOS address
98.Fa range
99(within
100.Li 0xe0000
101-
102.Li 0xfffff ) ,
103and a {
104.Dv NULL , Li 0 , 0
105} -terminated array of
106.Vt bios_oem_signature
107structures which define the
108.Va anchor
109string, an
110.Va offset
111from the beginning of the match (which may be negative), and
112.Va totlen
113number of bytes to be collected from BIOS memory starting at that offset.
114Unmatched anchors are ignored, whereas matches are copied from BIOS memory
115starting at their corresponding
116.Vt offset
117with unprintable characters being replaced with space, and consecutive spaces
118being suppressed.
119This composed string is stored in
120.Fa buffer
121up to the given
122.Fa maxlen
123bytes (including trailing
124.Ql \e0 ,
125and any trailing space suppressed).
126If an error is encountered, i.e.\& trying to read out of said BIOS range,
127other invalid input, or
128.Fa buffer
129overflow, a negative integer is returned, otherwise the
130length of the composed string is returned.
131In particular, a return
132value of 0 means that none of the given anchor strings were found in
133the specified BIOS memory range.
134.It Fn BIOS_VADDRTOPADDR
135Returns the effective physical address which corresponds to the kernel
136virtual address
137.Fa addr .
138.It Fn BIOS_PADDRTOVADDR
139Returns the kernel virtual address which corresponds to the effective
140physical address
141.Fa addr .
142.It SMBIOStable
143If not NULL, points to a
144.Ft struct SMBIOS_table
145structure containing information read from the System Management BIOS table
146during system startup.
147.It DMItable
148If not NULL, points to a
149.Ft struct DMI_table
150structure containing information read from the Desktop Management Interface
151parameter table during system startup.
152.El
153.Sh BIOS32
154At system startup, the BIOS is scanned for the BIOS32 Service Directory
155(part of the PCI specification), and the existence of the directory is
156recorded.
157This can then be used to locate other services.
158.Bl -tag -width 20n
159.It Fn bios32_SDlookup
160Attempts to locate the BIOS32 service matching the 4-byte identifier
161passed in the
162.Fa ident
163field of the
164.Fa ent
165argument.
166.It Fn bios32
167Calls a bios32 function.
168This presumes that the function is capable of
169working within the kernel segment (normally the case).
170The virtual address
171of the entrypoint is supplied in
172.Fa entry
173and the register arguments to the function are supplied in
174.Fa args .
175.It PCIbios
176If not NULL, points to a
177.Ft struct bios32_SDentry
178structure describing the PCI BIOS entrypoint which was found during system
179startup.
180.El
181