diff options
Diffstat (limited to 'include/linux/efi.h')
| -rw-r--r-- | include/linux/efi.h | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/include/linux/efi.h b/include/linux/efi.h index 8269bcb8ccf7..a686ca9a7e5c 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -1020,6 +1020,28 @@ extern int efi_memattr_init(void); extern int efi_memattr_apply_permissions(struct mm_struct *mm, efi_memattr_perm_setter fn); +/* + * efi_early_memdesc_ptr - get the n-th EFI memmap descriptor + * @map: the start of efi memmap + * @desc_size: the size of space for each EFI memmap descriptor + * @n: the index of efi memmap descriptor + * + * EFI boot service provides the GetMemoryMap() function to get a copy of the + * current memory map which is an array of memory descriptors, each of + * which describes a contiguous block of memory. It also gets the size of the + * map, and the size of each descriptor, etc. + * + * Note that per section 6.2 of UEFI Spec 2.6 Errata A, the returned size of + * each descriptor might not be equal to sizeof(efi_memory_memdesc_t), + * since efi_memory_memdesc_t may be extended in the future. Thus the OS + * MUST use the returned size of the descriptor to find the start of each + * efi_memory_memdesc_t in the memory map array. This should only be used + * during bootup since for_each_efi_memory_desc_xxx() is available after the + * kernel initializes the EFI subsystem to set up struct efi_memory_map. + */ +#define efi_early_memdesc_ptr(map, desc_size, n) \ + (efi_memory_desc_t *)((void *)(map) + ((n) * (desc_size))) + /* Iterate through an efi_memory_map */ #define for_each_efi_memory_desc_in_map(m, md) \ for ((md) = (m)->map; \ |