payloads/libpayload/arch/x86/boot_media.c

   1 /* SPDX-License-Identifier: BSD-3-Clause */
   2
   3 #include <arch/virtual.h>
   4 #include <boot_device.h>
   5 #include <commonlib/bsd/cb_err.h>
   6 #include <stddef.h>
   7 #include <string.h>
   8 #include <sysinfo.h>
   9
  10 __attribute__((weak)) ssize_t boot_device_read(void *buf, size_t offset, size_t size)
  11 {
  12         /* Memory-mapping usually only works for the top 16MB. */
  13         if (!lib_sysinfo.boot_media_size || lib_sysinfo.boot_media_size - offset > 16 * MiB)
  14                 return CB_ERR_ARG;
  15         const void *const ptr = phys_to_virt(0 - lib_sysinfo.boot_media_size + offset);
  16         memcpy(buf, ptr, size);
  17         return size;
  18 }