From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from co1outboundpool.messaging.microsoft.com (co1ehsobe004.messaging.microsoft.com [216.32.180.187]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (Client CN "mail.global.frontbridge.com", Issuer "MSIT Machine Auth CA 2" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 72D982C02B8 for ; Thu, 11 Jul 2013 07:40:18 +1000 (EST) Date: Wed, 10 Jul 2013 16:40:03 -0500 From: Scott Wood Subject: Re: [PATCH] powerpc/85xx: enable the math emulation for the corenet64_smp_defconfig To: Kevin Hao In-Reply-To: <1373420992-25167-1-git-send-email-haokexin@gmail.com> (from haokexin@gmail.com on Tue Jul 9 20:49:52 2013) Message-ID: <1373492403.8183.234@snotra> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; delsp=Yes; format=Flowed Cc: linuxppc List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 07/09/2013 08:49:52 PM, Kevin Hao wrote: > I got the following error on my t4240qds board. > ntpd[2713]: unhandled signal 4 at 0fd5b448 nip 0fd5b448 lr 0fd5b424 =20 > code 30001 >=20 > The root cause is that the float point instruction 'fsqrt' is used. > But this instruction is not implemented on e6500 core. Even this > does seem a gcc bug, I would like to enable the math emulation > in the kernel to workaround this kind of issue. I'll apply this, but we should add PPC_WARN_EMULATED to math-emu so =20 that people know when their toolchain is emitting things that require =20 emulation. It'd also be nice if we had an option to only include the portions of =20 math-emu that are known to be missing in some CPUs (excluding CPUs that =20 are missing the entire FPU, of course). Besides its effect on kernel =20 image size, in my experience math-emu adds a non-trivial amount of time =20 to a kernel build. -Scott=