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Date: Tue, 20 Jan 2009 19:04:49 -0800 From: Hiroshi Shimamoto <h-shimamoto@...jp.nec.com> To: Justin Madru <jdm64@...ab.com> Cc: "Justin P. Mattock" <justinmattock@...il.com>, Jesper Juhl <jj@...osbits.net>, lkml <linux-kernel@...r.kernel.org>, John Stoffel <john@...ffel.org>, Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com> Subject: Re: [bisected] 2.6.29-rc1 Firefox crashing on page load Justin Madru wrote: > Hiroshi Shimamoto wrote: >> Justin Madru wrote: >> >>> Hiroshi Shimamoto wrote: >>> >>>> Justin Madru wrote: >>>> >>>> >>>>> Hiroshi Shimamoto wrote: >>>>> >>>>> >>>>>> Justin Madru wrote: >>>>>> >>>>>> >>>>>>> Ok, finally bisected the bug, but the commit isn't related to networking! >>>>>>> I did: git revert 4217458dafaa57d8e26a46f5d05ab8c53cf64191 >>>>>>> on current git and that fixed the bug. >>>>>>> >>>>>>> By the way, how do I undo my git revert, so I'm back to a pristine tree? >>>>>>> I want to drop my changes - the revert. >>>>>>> Also how do I find the commit that merged/pulled in this commit? >>>>>>> >>>>>>> commit 4217458dafaa57d8e26a46f5d05ab8c53cf64191 >>>>>>> Author: Hiroshi Shimamoto <h-shimamoto@...jp.nec.com> >>>>>>> Date: Fri Dec 5 17:17:09 2008 -0800 >>>>>>> >>>>>>> x86: signal: change type of paramter for sys_rt_sigreturn() >>>>>>> >>>>>>> Impact: cleanup on 32-bit >>>>>>> >>>>>>> Peter pointed this parameter can be changed. >>>>>>> >>>>>>> Signed-off-by: Hiroshi Shimamoto <h-shimamoto@...jp.nec.com> >>>>>>> Signed-off-by: Ingo Molnar <mingo@...e.hu> >>>>>>> >>>>>>> >>>>>> Hi, >>>>>> thanks for reporting. >>>>>> >>>>>> I'm not sure why this commit affects. >>>>>> Can you check vmlinux? size, objdump, etc. >>>>>> On my environment, the generated code looks same. >>>>>> >>>>>> Thanks, >>>>>> Hiroshi >>>>>> >>>>>> >>>>>> >>>>> I tried to do an objdump but it gave an error. How am I suppose to do an >>>>> objdump? >>>>> >>>>> $ objdump -x /boot/vmlinuz-2.6.29-rc2-git >>>>> objdump: /boot/vmlinuz-2.6.29-rc2-git: File format not recognized >>>>> $ readelf -a /boot/vmlinuz-2.6.29-rc2-git >>>>> readelf: Error: Unable to seek to 0xc031f2eb for section headers >>>>> readelf: Error: Not an ELF file - it has the wrong magic bytes at the start >>>>> $ ls -la /boot/vmlinuz-2.6.29-rc2-git >>>>> -rw-r--r-- 1 root root 2286480 2009-01-19 18:44 /boot/vmlinuz-2.6.29-rc2-git >>>>> >>>>> >>>> not vmlinuz, vmlinux. >>>> vmlinuz is a compressed kernel, it is not ELF file. >>>> Usually vmlinux is generated in top of source directory. >>>> I can see disassembled image with objdump -d vmlinux. >>>> >>>> Thanks, >>>> Hiroshi >>>> >>>> >>>> >>> Sorry, didn't know. I tried objdump -d vmlinux, but the resulting file >>> is ~50MB! >>> Is there a smaller section you're interested in, because that would be >>> hard to send. >>> Or am I doing it wrong again? >>> >> that's OK. No need to send the disassembled result. >> You can diff disassembled file. >> I guess your GCC generates different code when the patch is reverted. >> >> Thanks, >> Hiroshi >> >> > Ok, I tried, I really did. But no mater what I did the diff was even bigger > if not the same size as the original dump! I even tried to cut out the > first two fields with > cut -f3- dump-revert > dump-revert2 > but that wouldn't shrink the diff size (100,000+ lines). I'm sorry for lack of explanations. The patch changes sys_rt_sigreturn(), it means GCC might generate different code for that function. And might be different size, it causes all codes after sys_rt_sigreturn() will looks different. So I think you can see the difference begins from sys_rt_sigreturn(). > > Does gcc output fluctuate this wildly with such little change? > Is there a config option that allows gcc to randomize the output? > I recompiled just to make sure, and even two recompiles of the same > source (no revert) > resulted in a different sha1 hash (didn't test the objdump diff). > The only thing I can think of is that I compile with -O3 instead of -O2. > > I'm sorry, but unless you have any suggestions I've decided to just upload > the vmlinux files to my server (<40KB up speed) > http://jdserver.homelinux.org/bugreports/002/ > and rapidshare > http://rapidshare.com/files/186890846/vmlinux.tar.bz2.html > http://rapidshare.com/files/186890848/data-norevert.tar.bz2.html > http://rapidshare.com/files/186890849/data-revert.tar.bz2.html thanks for uploading vmlinux, will see the difference. And sorry again, actually, it's just for my curiosity. I'd like to know what difference this is. On my environment GCC(4.2.4-1ubuntu3 and 4.3.2) generates same binary... > > By the way Ingo has already added the revert to tip/master > http://git.kernel.org/?p=linux/kernel/git/tip/linux-2.6-tip.git;a=commit;h=1d03950243904c89b8854c10516932b029c2a8fa Yeah, Ingo knows what GCC does. I don't know so much. Thanks, Hiroshi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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