Re: [Crash-utility] [PATCH] add arm support for libgcore

Hi HATAYAMA, On Tue, Feb 14, 2012 at 9:37 AM, HATAYAMA Daisuke <d.hatayama(a)jp.fujitsu.com&gt; wrote: > From: Lei Wen <adrian.wenl(a)gmail.com&gt; > Subject: Re: [Crash-utility] [PATCH] add arm support for libgcore > Date: Mon, 13 Feb 2012 17:03:02 +0800 > >> Hi Hatayama, >> >> On Mon, Feb 13, 2012 at 4:33 PM, HATAYAMA Daisuke >> <d.hatayama(a)jp.fujitsu.com&gt; wrote: >>> Hello Lei, >>> >>> Thanks for making patch. I'll check your patch this week, but I have >>> two things to ask you. >>> >>> 1. I don't know arm architecture at all and I don't have arm >>> machine. What I can do is only testing common part and regression test >>> on x86 architecture. Please maintain arm part yourself. >> >> Sure, it is my pleasure. :) >> >>> >>> 2. Could you tell me specific kernel versions you have tested this >>> patch in? I myself have yet to do this, but now I think it necessary >>> to make such a list. I imagine just like makedumpfile's SUPPORTED >>> KERNELS described in its README. I'll put them in gcore's README and >>> then ask Dave to add them into description in distribution page. >> >> I am current testing with kernel 2.6.35.7 and 3.0.8, and they are both ok. > > I see. > >> But I see below warnings during extracting, while the extracted core >> dump image is OK for gdb, I don't know whether it there is still some missing in >> original implementation, or those pages just don't existed in memory? >> >> gcore: PT_LOAD[165]: af900000 - af90e000 >> gcore: WARNING: page fault at af909000 >> gcore: WARNING: page fault at af90d000 > > These are verbose messages, which you can specify which to display via > -v option. Please see help message in detail. However, important is > "page fault" message below. > >> gcore: WARNING: page fault at af909000 >> gcore: WARNING: page fault at af90d000 > > Most of crash dump mechanism doesn't collect swap space, such as > kdump, diskdump, so in essence, crash gcore doesn't try to collect > such paged-out user-space memory. > > crash gcore instead fills the paged-out memory with zero; this > is easier implementation than reconstracting program headers. > > The reason why I've included the ``page fault'' in the default warning > message is to avoid the situation where users get confused they have > successfully got complete user-space coredump. > > GDB tends to work well because part of user stack necessary for > backtrace is not paged out most of time; of course, the backtrace > would fail if paged-out. > > Thanks. > HATAYAMA, Daisuke > I see, thanks for detailed explanation. My another curious is whether we could refill those missing swapped page, if we provide whole swap partition data? Thanks, Lei