linux-kernel - Re: BUG: early intel microcode update violating alignment rules

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Message-ID: <53E8D876.1060004@zytor.com>
Date:	Mon, 11 Aug 2014 07:51:34 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Henrique de Moraes Holschuh <hmh@....eng.br>,
	Borislav Petkov <bp@...en8.de>,
	Fenghua Yu <fenghua.yu@...el.com>
CC:	linux-kernel@...r.kernel.org
Subject: Re: BUG: early intel microcode update violating alignment rules

On 08/09/2014 04:19 PM, Henrique de Moraes Holschuh wrote:
> 
> This will only happen when the microcode update file data inside the early
> initramfs archive is not 16-byte aligned.  Unfortunately, the cpio format
> used in the early initramfs aligns the member file data just to 4-byte
> boundaries.
> 
> Is there a way to fix this in the kernel for the BSP?  We already have
> several microcode updates that are >16KiB in size and they seem to be
> getting bigger and bigger, so doing it on the stack is out.
> 
> Maybe there is a 64KiB scratch area that could be used just to get the BSP
> microcode update done?  vmalloc isn't available that early, but it can be
> used to fix the issue for the APs.
> 

We could put a buffer in the initdata region (we really could use an
initbss region!) or in the brk.

	-hpa

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