[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [Question] dump memory when host pci device is used by
From: |
Wen Congyang |
Subject: |
Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest |
Date: |
Fri, 21 Oct 2011 15:50:36 +0800 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100413 Fedora/3.0.4-2.fc13 Thunderbird/3.0.4 |
At 10/21/2011 03:11 PM, Jan Kiszka Write:
> 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.
Cc Dave Anderson. He knows how crash uses gdb.
I think that crash does not fork a task to execute gdb, and gdb is a part of
crash.
Thanks
Wen Congyang
>
> Jan
>
- Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest, (continued)
- Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest, KAMEZAWA Hiroyuki, 2011/10/18
- Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest, Jan Kiszka, 2011/10/19
- Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest, Wen Congyang, 2011/10/19
- Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest, Jan Kiszka, 2011/10/20
- Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest, Wen Congyang, 2011/10/20
- Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest, Jan Kiszka, 2011/10/21
- Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest,
Wen Congyang <=
- Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest, Dave Anderson, 2011/10/21
- Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest, Jan Kiszka, 2011/10/21
- Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest, Richard W.M. Jones, 2011/10/21
- Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest, Wen Congyang, 2011/10/23
- Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest, Dave Anderson, 2011/10/24
- Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest, Avi Kivity, 2011/10/24
- Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest, Dave Anderson, 2011/10/24
- Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest, Avi Kivity, 2011/10/24
- Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest, Dave Anderson, 2011/10/24
- Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest, Wen Congyang, 2011/10/24