linux-kernel - Re: Build regressions/improvements in v3.4-rc7

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Date:	Wed, 16 May 2012 18:59:33 +0300
From:	"Kasatkin, Dmitry" <dmitry.kasatkin@...el.com>
To:	James Bottomley <James.Bottomley@...senpartnership.com>
Cc:	Geert Uytterhoeven <geert@...ux-m68k.org>,
	linux-kernel@...r.kernel.org,
	Linuxppc-dev <linuxppc-dev@...abs.org>,
	Parisc List <linux-parisc@...r.kernel.org>,
	"the arch/x86 maintainers" <x86@...nel.org>,
	James Morris <jmorris@...ei.org>
Subject: Re: Build regressions/improvements in v3.4-rc7

On Wed, May 16, 2012 at 5:46 PM, James Bottomley
<James.Bottomley@...senpartnership.com> wrote:
> On Wed, 2012-05-16 at 10:47 +0200, Geert Uytterhoeven wrote:
>> On Wed, May 16, 2012 at 10:30 AM, Geert Uytterhoeven
>> <geert@...ux-m68k.org> wrote:
>>   + lib/mpi/generic_mpih-mul1.c: error: inconsistent operand
>> constraints in an 'asm':  => 50:70
>>   + lib/mpi/generic_mpih-mul2.c: error: inconsistent operand
>> constraints in an 'asm':  => 49:70
>>   + lib/mpi/generic_mpih-mul3.c: error: inconsistent operand
>> constraints in an 'asm':  => 49:70
>>   + lib/mpi/mpih-div.c: error: inconsistent operand constraints in an
>> 'asm':  => 135:122, 135:371, 97:122, 106:121, 106:370, 97:371
>>
>> parisc-allmodconfig
>
> Wow, lib/mpi/ is a complete horror: it's full of hand crafted asm code.
> The error in this case appears to be that umul_ppm() is implemented as
> an xmpyu instruction.  That's a floating point instruction.  We
> deliberately compile the kernel with floating point disabled because we
> don't want to save and restore the floating point register file on each
> context switch, hence the operand constraints are unsatisfiable.
>
> It appears to be completely untested on non-x86 and to have been
> imported via the security tree ... what are we supposed to do with this?
> I thought the general principle was that asm code was really supposed to
> be confined to the arch directories?
>
> James
>
>

Yes.. it is suxx.
But it is only longlong.h and inherited from gpg..
And now there is a stuff such as /include/math-emu/soft-fp and
<stdlib/longlong.h>
I planned to look to that but now I will start doing it right away.

- Dmitry
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