xref: /qemu/include/qemu/mmap-alloc.h (revision a976a99a)
1 #ifndef QEMU_MMAP_ALLOC_H
2 #define QEMU_MMAP_ALLOC_H
3 
4 
5 size_t qemu_fd_getpagesize(int fd);
6 
7 /**
8  * qemu_ram_mmap: mmap anonymous memory, the specified file or device.
9  *
10  * mmap() abstraction to map guest RAM, simplifying flag handling, taking
11  * care of alignment requirements and installing guard pages.
12  *
13  * Parameters:
14  *  @fd: the file or the device to mmap
15  *  @size: the number of bytes to be mmaped
16  *  @align: if not zero, specify the alignment of the starting mapping address;
17  *          otherwise, the alignment in use will be determined by QEMU.
18  *  @qemu_map_flags: QEMU_MAP_* flags
19  *  @map_offset: map starts at offset of map_offset from the start of fd
20  *
21  * Internally, MAP_PRIVATE, MAP_ANONYMOUS and MAP_SHARED_VALIDATE are set
22  * implicitly based on other parameters.
23  *
24  * Return:
25  *  On success, return a pointer to the mapped area.
26  *  On failure, return MAP_FAILED.
27  */
28 void *qemu_ram_mmap(int fd,
29                     size_t size,
30                     size_t align,
31                     uint32_t qemu_map_flags,
32                     off_t map_offset);
33 
34 void qemu_ram_munmap(int fd, void *ptr, size_t size);
35 
36 /*
37  * Abstraction of PROT_ and MAP_ flags as passed to mmap(), for example,
38  * consumed by qemu_ram_mmap().
39  */
40 
41 /* Map PROT_READ instead of PROT_READ | PROT_WRITE. */
42 #define QEMU_MAP_READONLY   (1 << 0)
43 
44 /* Use MAP_SHARED instead of MAP_PRIVATE. */
45 #define QEMU_MAP_SHARED     (1 << 1)
46 
47 /*
48  * Use MAP_SYNC | MAP_SHARED_VALIDATE if supported. Ignored without
49  * QEMU_MAP_SHARED. If mapping fails, warn and fallback to !QEMU_MAP_SYNC.
50  */
51 #define QEMU_MAP_SYNC       (1 << 2)
52 
53 /*
54  * Use MAP_NORESERVE to skip reservation of swap space (or huge pages if
55  * applicable). Bail out if not supported/effective.
56  */
57 #define QEMU_MAP_NORESERVE  (1 << 3)
58 
59 #endif
60