On 2011-10-20 12:03, Wen Congyang wrote: > 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.
crash is simply designed the wrong way around (from today's perspective): it should augment upstream gdb instead of forking it. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux