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SubjectRe: Fix built-in early-load Intel microcode alignment
On Sun, Jan 12, 2020 at 03:00:53PM +0200, Jari Ruusu wrote:
> Intel Software Developer's Manual, volume 3, chapter 9.11.6 says:
> "Note that the microcode update must be aligned on a 16-byte
> boundary and the size of the microcode update must be 1-KByte
> granular"
>
> When early-load Intel microcode is loaded from initramfs,
> userspace tool 'iucode_tool' has already 16-byte aligned those
> microcode bits in that initramfs image. Image that was created
> something like this:
>
> iucode_tool --write-earlyfw=FOO.cpio microcode-files...
>
> However, when early-load Intel microcode is loaded from built-in
> firmware BLOB using CONFIG_EXTRA_FIRMWARE= kernel config option,
> that 16-byte alignment is not guaranteed.
>
> Fix this by forcing all built-in firmware BLOBs to 16-byte
> alignment.
>
>
> Signed-off-by: Jari Ruusu <jari.ruusu@gmail.com>
>
> --- a/drivers/base/firmware_loader/builtin/Makefile
> +++ b/drivers/base/firmware_loader/builtin/Makefile
> @@ -17,7 +17,7 @@
> filechk_fwbin = \
> echo "/* Generated by $(src)/Makefile */" ;\
> echo " .section .rodata" ;\
> - echo " .p2align $(ASM_ALIGN)" ;\
> + echo " .p2align 4" ;\

Why not just keep ASM_ALIGN and define it to 4, with a nice
comment explaining the ucode stuff. Now we have a raw 4 here
and still use ASM_ALIGN which will depend on 64-bit or not.

Luis

> echo "_fw_$(FWSTR)_bin:" ;\
> echo " .incbin \"$(fwdir)/$(FWNAME)\"" ;\
> echo "_fw_end:" ;\
>
> --
> Jari Ruusu 4096R/8132F189 12D6 4C3A DCDA 0AA4 27BD ACDF F073 3C80 8132 F189

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