通过efi=debug 在kernel log中显示bios占用的memory

来源：互联网发布：硕士论文修改淘宝编辑：程序博客网时间：2024/06/08 19:31

在kernel commandline中加入efi=debug 就可以看到bios 占用的memory
efi=debug的解析函数如下：
static int __init parse_efi_cmdline(char *str)
{
   if (!str) {
       pr_warn("need at least one option\n");
       return -EINVAL;
   }

   if (parse_option_str(str, "debug"))
       set_bit(EFI_DBG, &efi.flags);

   if (parse_option_str(str, "noruntime"))
       disable_runtime = true;

   return 0;
}
early_param("efi", parse_efi_cmdline);

efi_init->reserve_regions
static __init void reserve_regions(void)
{
   efi_memory_desc_t *md;
   u64 paddr, npages, size;
//是否使能了debug flag就dump bios占用的memory
   if (efi_enabled(EFI_DBG))
       pr_info("Processing EFI memory map:\n");

   /*
   * Discard memblocks discovered so far: if there are any at this
   * point, they originate from memory nodes in the DT, and UEFI
   * uses its own memory map instead.
   */
   memblock_dump_all();
   memblock_remove(0, (phys_addr_t)ULLONG_MAX);
//
可见bios的memory信息是保存在efi.memmap 变量中
#define for_each_efi_memory_desc(md) \
   for_each_efi_memory_desc_in_map(&efi.memmap, md)

//
   for_each_efi_memory_desc(md) {
       paddr = md->phys_addr;
       npages = md->num_pages;

       if (efi_enabled(EFI_DBG)) {
           char buf[64];

           pr_info(" 0x%012llx-0x%012llx %s\n",
               paddr, paddr + (npages << EFI_PAGE_SHIFT) - 1,
               efi_md_typeattr_format(buf, sizeof(buf), md));
       }

       memrange_efi_to_native(&paddr, &npages);
       size = npages << PAGE_SHIFT;

       if (is_memory(md)) {
           early_init_dt_add_memory_arch(paddr, size);

           if (!is_usable_memory(md))
               memblock_mark_nomap(paddr, size);
       }
   }
}

实际可以打印的log如下：

[    0.000000] Processing EFI memory map:
[    0.000000]   0x000000000000-0x00000007ffff [Conventional Memory|   | | | | | |   |WB|WT|WC|UC]
[    0.000000]   0x000000080000-0x00000102ffff [Loader Data        |   | | | | | |   |WB|WT|WC|UC]
[    0.000000]   0x000001030000-0x00001fdfffff [Conventional Memory|   | | | | | |   |WB|WT|WC|UC]
[    0.000000]   0x00001fe00000-0x00001fe0ffff [Loader Data        |   | | | | | |   |WB|WT|WC|UC]
[    0.000000]   0x00001fe10000-0x00002def7fff [Conventional Memory|   | | | | | |   |WB|WT|WC|UC]
[    0.000000]   0x00002def8000-0x00002ee9efff [Loader Code        |   | | | | | |   |WB|WT|WC|UC]
[    0.000000]   0x00002ee9f000-0x00002fbfffff [Loader Data        |   | | | | | |   |WB|WT|WC|UC]
[    0.000000]   0x00002fc00000-0x00002fc1ffff [Boot Data          |   | | | | | |   |WB|WT|WC|UC]
[    0.000000]   0x00002fc20000-0x0000305dbfff [Conventional Memory|   | | | | | |   |WB|WT|WC|UC]
[    0.000000]   0x0000305dc000-0x000031453fff [Loader Data        |   | | | | | |   |WB|WT|WC|UC]
[    0.000000]   0x000031454000-0x00003147efff [Loader Code        |   | | | | | |   |WB|WT|WC|UC]
[    0.000000]   0x00003147f000-0x000031682fff [Boot Code          |   | | | | | |   |WB|WT|WC|UC]
[    0.000000]   0x000031683000-0x000039683fff [Boot Data          |   | | | | | |   |WB|WT|WC|UC]
[    0.000000]   0x000039684000-0x0000396effff [Boot Code          |   | | | | | |   |WB|WT|WC|UC]
[    0.000000]   0x0000396f0000-0x00003973ffff [Runtime Data       |RUN| | | | | |   |WB|WT|WC|UC]*
[    0.000000]   0x000039740000-0x00003978ffff [Runtime Code       |RUN| | | | | |   |WB|WT|WC|UC]*
[    0.000000]   0x000039790000-0x0000397dffff [ACPI Reclaim Memory|   | | | | | |   |WB|WT|WC|UC]*
[    0.000000]   0x0000397e0000-0x0000397effff [ACPI Memory NVS    |   | | | | | |   |WB|WT|WC|UC]*
[    0.000000]   0x0000397f0000-0x00003983ffff [ACPI Reclaim Memory|   | | | | | |   |WB|WT|WC|UC]*
[    0.000000]   0x000039840000-0x0000398bffff [Runtime Data       |RUN| | | | | |   |WB|WT|WC|UC]*

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