linux-kernel - Re: 3.1-rc6 boot problem reason searching

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Date:	Thu, 15 Sep 2011 11:56:35 -0700
From:	Andrew Lutomirski <luto@....edu>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	werner <w.landgraf@...ru>
Subject: Re: 3.1-rc6 boot problem reason searching

On Thu, Sep 15, 2011 at 11:23 AM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
> On Thu, Sep 15, 2011 at 11:15 AM, Linus Torvalds
> <torvalds@...ux-foundation.org> wrote:
>>
>> It *used* to have an alignment of 8 back before your patch to make the
>> pointers be relative due to the 64-bit pointers. But now all fields
>> are 32-bit, and it could easily have a size of just 12 bytes, getting
>> rid of the 'pad2' field, and getting rid of the '.balign 8's.
>
> IOW, maybe the correct patch is just the attached one.
>
> Werner, does this fix the boot for you? It gets rid of all the bogus
> alignment stuff, it's all wrong anyway, the altinstructions section
> entries are all 12 bytes long so it starts out sufficiently aligned,
> and it *stays* aligned because if anybody ever adds a non-12-byte
> entry that would be a huge bug regardless. So any extra alignment is
> just likely to be buggy and hide much bigger issues.
>
> This is COMPLETELY UNTESTED, just looking at the source.

If you want to apply it this late, fine with me.  It looks generally
sane, but I haven't tested it.

OTOH, I have tested the attached minimal patch on 32-bit and 64-bit.

--Andy

View attachment "my_patch.diff" of type "text/x-patch" (757 bytes)