Messages in this thread | | | Date | Tue, 2 Jun 2015 19:00:40 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH 1/1] x86/microcode: vsnprintf() might be unavailable |
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On Tue, Jun 02, 2015 at 07:49:53PM +0300, Andy Shevchenko wrote: > Initial paging setup is involved?
Yes, load_ucode_bsp happens before paging is enabled on 32-bit. And that should remain that way - we want microcode application as early as possible.
> Hmm… which Intel CPUs you run on?
processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 58 model name : Intel(R) Core(TM) i7-3520M CPU @ 2.90GHz stepping : 9 microcode : 0x1b
and an SNB one too.
> Ah, one more thing we run our kernel from kexec (I hope it's not a > case, but who knows).
Does it work when you boot a normal 32-bit kernel with builtin microcode on it?
In order to load built-in microcode, you'll have to enable the boot options in the commit message to
760d765b2bb6 ("x86/microcode: Parse built-in microcode early")
Let me know if something's not clear.
On Tue, Jun 02, 2015 at 07:46:29PM +0300, Andy Shevchenko wrote: > > @@ -533,7 +533,12 @@ static bool __init load_builtin_intel_microcode(struct cpio_data *cp) > > model = x86_model(eax); > > stepping = eax & 0xf; > > > > - sprintf(name, "intel-ucode/%02x-%02x-%02x", family, model, stepping); > > + *p++ = '/'; > > + p = hex_byte_pack(p, family); > > + *p++ = '-'; > > + p = hex_byte_pack(p, model); > > + *p++ = '-'; > > + p = hex_byte_pack(p, stepping); > > > > Forgot to add *p = '\0'; here, but it doesn't really mater for the idea. > > What I would like to tell that if I move 'call load_ucode_bsp' after > paging is done, it seems sprintf() starts working nicely.
Hmm, ok, so something's not able to stomach pre-paging. Can you dump something from the failure, RIP, stack, whatever?
Can I reproduce it?
> So, I don't know which fix is better (or neither),
See above.
> and wondering if we need to fix AMD part.
No need, AFAICT. It did work in my testing.
> P.S. It would be really nice to get an expert / detailed explanation > what is going on there.
Yeah, that's why I'm asking.
Thanks.
-- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply. --
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