From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933590AbbHLGZe (ORCPT ); Wed, 12 Aug 2015 02:25:34 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:47003 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933269AbbHLGZd (ORCPT ); Wed, 12 Aug 2015 02:25:33 -0400 Date: Tue, 11 Aug 2015 23:24:45 -0700 From: Christoph Hellwig To: katsuki.uwatoko@toshiba.co.jp Cc: linux-arm-kernel@lists.infradead.org, david@fromorbit.com, gangchen@rdamicro.com, linux@arm.linux.org.uk, karanvir.singh@hgst.com, luca@skylable.com, christopher.squires@hgst.com, edwin@skylable.com, wayne.burri@hgst.com, linux-kernel@vger.kernel.org, Linus Torvalds Subject: enabling libgcc for 64-bit divisions, was Re: PROBLEM: XFS on ARM corruption 'Structure needs cleaning' Message-ID: <20150812062445.GA4520@infradead.org> References: <5579B804.9050707@skylable.com> <20150612122108.GB60661@bfoster.bfoster> <557AD4D4.3010901@skylable.com> <20150612225209.GA20262@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 12, 2015 at 12:56:25AM +0000, katsuki.uwatoko@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?