From mboxrd@z Thu Jan 1 00:00:00 1970 From: hch@infradead.org (Christoph Hellwig) Date: Tue, 11 Aug 2015 23:24:45 -0700 Subject: enabling libgcc for 64-bit divisions, was Re: PROBLEM: XFS on ARM corruption 'Structure needs cleaning' In-Reply-To: References: <5579B804.9050707@skylable.com> <20150612122108.GB60661@bfoster.bfoster> <557AD4D4.3010901@skylable.com> <20150612225209.GA20262@dastard> Message-ID: <20150812062445.GA4520@infradead.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Aug 12, 2015 at 12:56:25AM +0000, katsuki.uwatoko at toshiba.co.jp wrote: > On Sat, 13 Jun 2015 08:52:09 +1000, Dave Chinner wrote: > > > Yup, that's looking like a toolchain bug. Thread about arm directory > > read corruption: > > I think that this is not a toolchain bug, this is related to > Subject: [PATCH v2 1/1] ARM : missing corrupted reg in __do_div_asm > http://www.spinics.net/lists/arm-kernel/msg426684.html Maybe it's time to rely on gcc to handle 64 bit divisions now? I've been pretty annoyed at the amount of 32-bit architecture build failures due to the lack of support for native 64-bit divisions, and the ugly do_div hackery to work around it. We're living in a world where we are using a lot of 64-bit CPUs and people optimize for them, so it might be a good time to start relying on the compiler to get these right on older CPUs. How bad is gcc's code for 64-bit divisions on arm and x86 these days? Is there still a good case for offloading work the compiler should be doing on the programmer?