From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <4C02B020.2040103@zytor.com> Date: Sun, 30 May 2010 11:36:16 -0700 From: "H. Peter Anvin" MIME-Version: 1.0 Subject: Re: [PATCH] x86, hweight: Fix UML boot crash References: <201005271944.09541.toralf.foerster@gmx.de> <20100530150214.GA1565@liondog.tnic> <201005301728.25976.toralf.foerster@gmx.de> <20100530170346.GC1565@liondog.tnic> In-Reply-To: <20100530170346.GC1565@liondog.tnic> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit To: Borislav Petkov , Geert Uytterhoeven , Borislav Petkov , =?UTF-8?B?VG9yYWxmIEbDtnJzdGVy?= , user-mode-linux-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org List-ID: On 05/30/2010 10:03 AM, Borislav Petkov wrote: > Obviously UML cannot stomach callee reg-saving trickery > introduced with d61931d89be506372d01a90d1755f6d0a9fafe2d (x86: > Add optimized popcnt variants) and oopses during boot: > http://marc.info/?l=linux-kernel&m=127522065202435&w=2 > > Go ahead and fall back to the software hweight* routines on UML. I actually don't understand why UML can't stomach that... it would work exactly the same in userspace as in kernel space. The only thing that I can think of is if UML overrides the CFLAGS including the per-file CFLAGS, but that would seem to cause all kinds of other issues. I would also be a lot happier if this was handled in than in . Finally, if UML really can't handle this, then ARCH_HWEIGHT_CFLAGS should be disabled on UML. This bothers me, because it really feels like something is fundamentally broken in UML tryingto track the upstream architecture, and this is just a bandage. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.