Re: [PATCH 2/6] x86/microcode: Merge early loader

From: Borislav Petkov
Date: Mon Nov 09 2015 - 05:12:20 EST

On Mon, Nov 09, 2015 at 10:42:13AM +0100, Harald Hoyer wrote:
> Will this work with kernels not supporting the microcode loading?
> Theoretically the old kernels would just unpack all cpios one after
> the other, right?

Well, what we should be doing is adding two paths to the initrd:

for AMD: kernel/x86/microcode/AuthenticAMD.bin
for Intel: kernel/x86/microcode/GenuineIntel.bin

I.e., the microcode blobs become part of the initrd, see
Documentation/x86/early-microcode.txt. The loader goes and opens the one
it needs at boot time.

You could also add a switch for convenience, something like
--no-microcode or so, so that dracut doesn't add it but if one wants to
not add microcode, one could also move it away from, say, /lib/firmware/
so that dracut simply doesn't find it. The --no-microcode might be more
convenient though.

Kernels which don't support microcode loading would simply not look for
that path.

Let me know if this doesn't make sense and if I need to test/look at



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