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Date: Thu, 13 Dec 2012 17:23:04 +0100
From: Florian Fainelli <florian@openwrt.org>
Organization: OpenWrt
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To: Linus Torvalds <torvalds@linux-foundation.org>
CC: Ingo Molnar <mingo@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>, Thomas Gleixner <tglx@linutronix.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: [RFC GIT PULL] "Nuke 386-DX/SX support" changes for v3.8
References: <20121211111026.GA26507@gmail.com> <CA+55aFzJX-EKC4Z98+KEaca0V27p8PxqZXiPox=TuuhytUTziw@mail.gmail.com>
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Le 12/12/12 19:04, Linus Torvalds a écrit :
> On Tue, Dec 11, 2012 at 3:10 AM, Ingo Molnar <mingo@kernel.org> wrote:
>>
>> This tree removes ancient-386-CPUs support and thus zaps quite a
>> bit of complexity:
>
> Btw, I think we should probably at least consider taking this one step
> further, and remove the dear old FPU emulation support too. Remove
> CONFIG_MATH_EMULATION and all of arch/x86/math-emu, along with a lot
> of small special cases.
>
> Or do people still use the 486SX?

Yes, the RDC-R321x SoC which is supported by mainline actually needs 
Math emulation to properly work.

>
> Now, the math emulation hasn't been all that fundamentally problematic
> (compared to lack of xadd etc), but it does result in some
> complexities in exception handling and ptrace (grep for HAVE_HWFP or
> "hard_math" or a number of other magic things). None of which have
> likely been tested at all in the last ten years, so who knows if it
> actually *works* or not.
>
> Maybe somebody could try booting with "no387". Does it actually work?

Ok, I could try that.
--
Florian