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

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