Re: [Xen-devel] [PATCH] xen/x86: Fix up rules when forcing -mno-sse

[Doug Goldstein <cardoe@xxxxxxxxxx>]

On Wed, Aug 12, 2015 at 10:38 AM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>> On 12.08.15 at 17:23, <cardoe@xxxxxxxxxx> wrote:
>> From: Nathan Rossi <nathan.rossi@xxxxxxxxxx>
>>
>> * When forcing -mno-sse specify -mfpmath=387 to avoid the fallback
>>   warning
>
> "the fallback warning" being what? I've never seen any, and I don't
> think I've ever heard anyone else say there was one.
>
> Apart from that I don't think -mfpmath=387 is what we want - we'd
> better tell the compiler to not use x87 registers at all.
>
> Jan
>

I guess I jumped the gun a bit. When targeting a corei7 based chip, Yocto uses
the following CFLAGS for the packages it builds:

-march=corei7 -mtune=corei7 -mfpmath=sse -msse4.2

The issue is the -mfpmath value.

-- 
Doug Goldstein

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