[PATCH] Fix remainder calculating bug in single floating pointdivision

Kumar Gala galak at kernel.crashing.org
Thu Jan 10 03:19:50 EST 2008


On Jan 9, 2008, at 9:38 AM, Liu Yu wrote:

>
>> -----Original Message-----
>> From: linuxppc-dev-bounces+b13201=freescale.com at ozlabs.org
>> [mailto:linuxppc-dev-bounces+b13201=freescale.com at ozlabs.org]
>> On Behalf Of Kumar Gala
>> Sent: Tuesday, January 08, 2008 2:20 PM
>> To: Dan Malek
>> Cc: Liu Yu; linuxppc-dev at ozlabs.org
>> Subject: Re: [PATCH] Fix remainder calculating bug in single
>> floating pointdivision
>>
>>
>> On Jan 6, 2008, at 2:44 PM, Dan Malek wrote:
>>
>>>
>>> On Jan 6, 2008, at 12:07 PM, Benjamin Herrenschmidt wrote:
>>>
>>>> It's nice to see somebody digging in that scary math emu stuff. If
>>>> you could also get rid of the warnings, it would be perfect :-)
>>>
>>> Yes, it is :-)  I didn't think it would have a life beyond MPC8xx.
>>>
>>>> .... that this code was lifted from
>>>> somewhere else (glibc ? gcc soft-float ?),
>>>
>>> It seems like a lifetime ago....  I copied the framework
>> from Sparc,
>>> and the internals from gcc soft-float.  I didn't change any of the
>>> internal emulation functions (hence, some of the warnings),
>> just the
>>> calling interface.
>>>
>>> While it's convenient, I still don't think kernel float emulation
>>> should be a solution.  The tools should generate soft-float for the
>>> applications and libraries.
>>
>> If we think this is really true, we could move to using include/math-
>> emu/* instead of the files in powerpc/math-emu.
>
> Why it's better to move to using include/math-emu.
> I found they have similar framework, is powerpc/math-emu evolved from
> include/math-emu?

* We dont really need more than one way in the kernel source tree to  
do math-emu
* include/math-emu is used by more archs so gets more review
* include/math-emu is closer to glibc soft-fp code so fixes to one  
apply cleanly to the other

- k



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