From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=42221 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PaYfW-0005Oj-UD for qemu-devel@nongnu.org; Wed, 05 Jan 2011 14:05:12 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PaYfV-0008PS-Da for qemu-devel@nongnu.org; Wed, 05 Jan 2011 14:05:10 -0500 Received: from e5.ny.us.ibm.com ([32.97.182.145]:46277) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PaYfV-0008P7-A8 for qemu-devel@nongnu.org; Wed, 05 Jan 2011 14:05:09 -0500 Received: from d01dlp02.pok.ibm.com (d01dlp02.pok.ibm.com [9.56.224.85]) by e5.ny.us.ibm.com (8.14.4/8.13.1) with ESMTP id p05Iftxf016991 for ; Wed, 5 Jan 2011 13:42:03 -0500 Received: from d01relay06.pok.ibm.com (d01relay06.pok.ibm.com [9.56.227.116]) by d01dlp02.pok.ibm.com (Postfix) with ESMTP id C63E44DE803F for ; Wed, 5 Jan 2011 14:02:14 -0500 (EST) Received: from d01av02.pok.ibm.com (d01av02.pok.ibm.com [9.56.224.216]) by d01relay06.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p05J4vjI1618034 for ; Wed, 5 Jan 2011 14:04:58 -0500 Received: from d01av02.pok.ibm.com (loopback [127.0.0.1]) by d01av02.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p05J4utG011784 for ; Wed, 5 Jan 2011 17:04:57 -0200 Date: Wed, 5 Jan 2011 13:04:51 -0600 From: Ryan Harper Subject: Re: [Qemu-devel] Re: [PATCH] Fix segfault with ram_size > 4095M without kvm Message-ID: <20110105190451.GD6249@us.ibm.com> References: <20101208160110.1b0c7c64@doriath> <4CFFCD10.6060500@linux.vnet.ibm.com> <20101208162745.60d085db@doriath> <20101225223552.GA9076@volta.aurel32.net> <20110104154902.GA30977@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110104154902.GA30977@us.ibm.com> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Aurelien Jarno Cc: qemu-devel@nongnu.org, Luiz Capitulino , Anthony Liguori , Ryan Harper , amit.shah@redhat.com, Richard Henderson * Ryan Harper [2011-01-04 09:49]: > * Aurelien Jarno [2010-12-25 16:37]: > > On Wed, Dec 08, 2010 at 04:27:45PM -0200, Luiz Capitulino wrote: > > > On Wed, 08 Dec 2010 12:23:12 -0600 > > > Anthony Liguori wrote: > > > > > > > On 12/08/2010 12:01 PM, Luiz Capitulino wrote: > > > > > Currently, x86_64-softmmu qemu segfaults when trying to use> 4095M memsize. > > > > > This patch adds a simple check and error message (much like the 2047 limit on > > > > > 32-bit hosts) on ram_size in the control path after we determine we're > > > > > not using kvm > > > > > > > > > > Upstream qemu-kvm is affected if using the -no-kvm option; this patch address > > > > > the segfault there as well. > > > > > > > > > > Signed-off-by: Ryan Harper > > > > > Signed-off-by: Aurelien Jarno > > > > > --- > > > > > NOTE: this patch was applied in the v0.12.x branch, but it seems it got > > > > > lost for master > > > > > > > > > > > > > No, it was intentional. We should fix the segv, this is not a known > > > > limitation but rather a bug. > > > > > > A TCG bug, I presume? > > > > > > > Do you have more details about this issue and how to reproduce it? > > At the time of the bug, it was something simple like: > > qemu-system-x86_64 -m 4097 -hda /dev/null > > we'd get an imediate segfault. As you say, I'm not seeing it now on > current git; I'll see about bisecting to see if we did get a fix for the > issue. I attempted to bisect, but there a couple commits around where the issue was fixed that broke git bisect =( That narrowed it down to about 5 commits to check. This the last git commit where I can reproduce the segfault with the above test case (qemu invocation). commit 0aef4261ac0ec9089ade0e3a92f986cb4ba7317e Author: Aurelien Jarno Date: Thu Mar 11 21:29:42 2010 +0100 target-ppc: fix evsrwu and evsrws (second try) Signed-off-by: Aurelien Jarno The next 4 commits don't compile so they are untest-able: commit 14f24e1465edc44b9b4d89fbbea66e06088154e1 - fails to build with: - ./configure --target-list=x86_64-softmmu && make clean && make /home/rharper/work/git/qemu/exec.c: In function 'phys_page_find_alloc': /home/rharper/work/git/qemu/exec.c:341: error: #error unsupported TARGET_PHYS_ADDR_SPACE_BITS /home/rharper/work/git/qemu/exec.c: In function 'phys_page_for_each': /home/rharper/work/git/qemu/exec.c:1670: error: #error unsupported TARGET_PHYS_ADDR_SPACE_BITS make[1]: *** [exec.o] Error 1 make: *** [subdir-x86_64-softmmu] Error 2 commit 7bc7b099dfa38a856b1bc892c0f9f3d6fe28e170 - fails to build with: - ./configure --target-list=x86_64-softmmu && make clean && make /home/rharper/work/git/qemu/exec.c: In function 'phys_page_find_alloc': /home/rharper/work/git/qemu/exec.c:341: error: #error unsupported TARGET_PHYS_ADDR_SPACE_BITS /home/rharper/work/git/qemu/exec.c: In function 'phys_page_for_each': /home/rharper/work/git/qemu/exec.c:1670: error: #error unsupported TARGET_PHYS_ADDR_SPACE_BITS make[1]: *** [exec.o] Error 1 make: *** [subdir-x86_64-softmmu] Error 2 commit b9f83121a13153536d886305414b540460c34508 - fails to build with: - ./configure --target-list=x86_64-softmmu && make clean && make /home/rharper/work/git/qemu/exec.c: In function 'phys_page_find_alloc': /home/rharper/work/git/qemu/exec.c:341: error: #error unsupported TARGET_PHYS_ADDR_SPACE_BITS /home/rharper/work/git/qemu/exec.c: In function 'phys_page_for_each': /home/rharper/work/git/qemu/exec.c:1670: error: #error unsupported TARGET_PHYS_ADDR_SPACE_BITS make[1]: *** [exec.o] Error 1 make: *** [subdir-x86_64-softmmu] Error 2 commit 5270589032f450ae7c3448730855aa18ff68ccff - fails to build with: - ./configure --target-list=x86_64-softmmu && make clean && make /home/rharper/work/git/qemu/exec.c: In function 'phys_page_find_alloc': /home/rharper/work/git/qemu/exec.c:341: error: #error unsupported TARGET_PHYS_ADDR_SPACE_BITS /home/rharper/work/git/qemu/exec.c: In function 'phys_page_for_each': /home/rharper/work/git/qemu/exec.c:1670: error: #error unsupported TARGET_PHYS_ADDR_SPACE_BITS make[1]: *** [exec.o] Error 1 make: *** [subdir-x86_64-softmmu] Error 2 And this commit compiles and the test case no longer segfaults. So I'd say things are fixed at this point. commit 5cd2c5b6ad75c46d40118ac67c0c09d4e7930a65 - compiles and issue is no longer present. - ./configure --target-list=x86_64-softmmu && make clean && make && sudo x86_64-softmmu/qemu-syem-x86_64 -L pc-bios -hda /dev/null -m 4097 -- Ryan Harper Software Engineer; Linux Technology Center IBM Corp., Austin, Tx ryanh@us.ibm.com