Re: [coreboot] When does AMD release the fam15 spectre microcode updates?

[Rudolf Marek]

Hi,

Dne 17.4.2018 v 12:09 awokd via coreboot napsal(a):
> At what byte locations in the header is the equivalence table? I was
> looking for this...

Hm I'm not aware where is it documented, or if there is some tool to manipulate it/dump the structure. Maybe
it could be added to some existing tool?

Here is what I deduced from Linux arch/x86/kernel/cpu/microcode/amd.c
+ header files

+ 0 u32 UCODE_MAGIC 
+ 4 u32 UCODE_EQUIV_CPU_TABLE_TYPE (0x0)
+ 8 u32 size of following equiv table say "N"

Then this follows, the last table has installed_cpu_cpuid == 0

u32 installed_cpu_cpuid
u32 fixed_errata_mask
u32 fixed_errata_compare
u16 equiv_cpu
u16 res

+ N u32 UCODE_UCODE_TYPE (0x1)
+ N + 4 u32 sizeof blob (without this header)
+ N + 8 microcode blob from github follows here
...
Then after that, there clould be again

+ X u32 UCODE_UCODE_TYPE
+ X + 4 u32 SECTION_SIZE
+ X + 8 microcode header (blob from github follows here)

The microcode blob has the header which already matches the usual microcode header:

struct microcode_header_amd {
        u32     data_code;
        u32     patch_id;
        u16     mc_patch_data_id;
        u8      mc_patch_data_len;
        u8      init_flag;
        u32     mc_patch_data_checksum;
        u32     nb_dev_id;
        u32     sb_dev_id;
        u16     processor_rev_id;
        u8      nb_rev_id;
        u8      sb_rev_id;
        u8      bios_api_rev;
        u8      reserved1[3];
        u32     match_reg[8];
} __attribute__((packed));

Thanks
Rudolf