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Date: Wed, 09 Jun 2010 12:08:58 +0300
From: Boaz Harrosh <bharrosh@panasas.com>
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Subject: Re: [uml-devel] [PATCH resend] um, hweight: Fix UML boot crash
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To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>, =?UTF-8?B?VG9yYWxmIEbDtnJzdGVy?= <toralf.foerster@gmx.de>, uml-devel <user-mode-linux-devel@lists.sourceforge.net>, linux-kernel <linux-kernel@vger.kernel.org>, Jeff Dike <jdike@addtoit.com>, Andrew Morton <akpm@linux-foundation.org>, "Rafael J. Wysocki" <rjw@sisk.pl>
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On 06/09/2010 11:46 AM, Geert Uytterhoeven wrote:
> On Wed, Jun 9, 2010 at 10:09, Boaz Harrosh <bharrosh@panasas.com> wrote:
>> On 06/09/2010 11:04 AM, Boaz Harrosh wrote:
>>> From: Borislav Petkov <bp@alien8.de>
>>>
>>> Obviously UML cannot stomach callee reg-saving trickery
>>> introduced with d61931d89be506372d01a90d1755f6d0a9fafe2d
>>> (x86: Add optimized popcnt variants) and oopses during boot:
>>> http://marc.info/?l=linux-kernel&m=127522065202435&w=2
>>>
>>> Redirect arch_hweight.h include from the x86 portion to the generic
>>> arch_hweight.h which is a fallback to the software hweight routines.
>>>
>>> LKML-Reference: <201005271944.09541.toralf.foerster@gmx.de>
>>> Signed-off-by: Borislav Petkov <bp@alien8.de>
> 
> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>

Tested-by: Boaz Harrosh <bharrosh@panasas.com>

> 
>> who's going to push this ASAP. I was just (again) 3/4 through a bisect
>> on 2.6.35-rc2. When I finally realized "Hey that patch, I forgot".
>> (My concentration is not what it used to be)
>>
>> Please push this, someone
> 
> Peter, are you happy with this?
> Although we still don't know why UML cannot grok it, it does fix a
> regression in post-2.6.34.
> 

I have x86_64 setup (host and guest). Without this I'm unable to boot any
UML image (2.6.35-rc2). With it all is well as before.

Boaz
>>> ---
>>>  arch/um/include/asm/arch_hweight.h |    6 ++++++
>>>  1 files changed, 6 insertions(+), 0 deletions(-)
>>>  create mode 100644 arch/um/include/asm/arch_hweight.h
>>>
>>> diff --git a/arch/um/include/asm/arch_hweight.h b/arch/um/include/asm/arch_hweight.h
>>> new file mode 100644
>>> index 0000000..c656cf4
>>> --- /dev/null
>>> +++ b/arch/um/include/asm/arch_hweight.h
>>> @@ -0,0 +1,6 @@
>>> +#ifndef _ASM_UM_HWEIGHT_H
>>> +#define _ASM_UM_HWEIGHT_H
>>> +
>>> +#include <asm-generic/bitops/arch_hweight.h>
>>> +
>>> +#endif
> 
> Gr{oetje,eeting}s,
> 
> 						Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> 							    -- Linus Torvalds