At 10/20/2011 05:41 PM, Jan Kiszka Write: > On 2011-10-20 03:22, Wen Congyang wrote: >>>> I didn't read full story but 'crash' is used for investigating kernel core >>>> generated >>>> by kdump for several years. Considering support service guys, virsh dump >>>> should support >>>> a format for crash because they can't work well at investigating vmcore by >>>> gdb. >>>> >>>> crash has several functionality useful for them as 'show kerne log', >>>> 'focus on a cpu' >>>> 'for-each-task', 'for-each-vma', 'extract ftrace log' etc. >>>> >>>> Anyway, if a man, who is not developper of qemu/kvm, should learn 2 tools >>>> for >>>> investigating kernel dump, it sounds harmful. >>> >>> Right, that's why everything (live debugging & crash analysis) should be >>> consolidated on the long run over gdb. crash is architecturally obsolete >>> today - not saying it is useless! >> >> I do not know why crash is obsoleted today. Is there a new better tool to >> instead >> crash? > > I'm not aware of equally powerful (python) scripts for gdb as > replacement, but I think it's worth starting a porting effort at some point. > >> >> At least, I always use crash to live debugging & crash analysis. > > Then you may answer some questions to me: > - Can you attach to a remote target (kgdb, qemu, etc.) and how?
No. crash's live debugging only can work the kernel is live. I can use it get some var's value, or some other information from kernel. If kernel panics, we can use gdb to attach to a remote target as you said. But on end user machine, we can not do it, we should dump the memory into a file and analyze it in another machine while the end user's guest can be restart. > - Can you use it with latest gdb versions or is the gdb functionality > hard-wired due to an embedded gdb core in crash (that's how I > understood Christoph's reply to this topic) If I use crash, I can not use latest gdb versions. Do we always need to use the latest gdb versions? Currently, gdb-7.0 is embedded into crash, and it is enough to me. If the gdb embedded into crash cannot anaylze the vmcore, I think we can update it and rebuild crash. Thanks Wen Congyang. > > Thanks, > Jan >