[Crash-utility] Using crash to debug a domU on xen.

[Don Slutz]

Sorry for the late reply.  I was off attending the Xen Developer 
Conference, and then testing out the latest kexec code, and am just 
getting back to this,

On 10/23/13 12:37, Daniel Kiper wrote:
> On Tue, Oct 22, 2013 at 07:03:19PM +0200, Daniel Kiper wrote:
>> Hi,
>>
>> Sorry for late reply but I am very busy now.
>>
>> On Thu, Oct 17, 2013 at 03:25:25PM -0400, Don Slutz wrote:
>>> On 10/16/13 09:49, Petr Tesarik wrote:
>>>> On Tue, 15 Oct 2013 12:02:51 -0400
>>>> Don Slutz <dslutz at verizon.com> wrote:
>>>>
>>>>> I have some code that allows this.  See the following mail thread:
>>>>>
>>>>> http://permalink.gmane.org/gmane.comp.emulators.xen.devel/174807
>>>>>
>>>>> The questions are:
>>>>>
>>>>>   1. Does remote access have a specification?
>>>>>   2. Is it supported?
>>>> I have never even made it to work. But since there's now some new use
>>>> for it, I wouldn't object reviving the code.
>>>>
>>> Good.
>>>>>   3. Should the code be part of xen or crash?
>>>> I think it should be part of xen, because it needs the xen development
>>>> files, which would be a new dependency for the crash utility. Also, the
>>>> development cycle is more aligned with xen than crash.
>>>>
>>>> Just my two cents,
>>>> Petr T
>>> That is why I started with it in xen.  Not sure where it will end up.
>> I do not know protocol details but I think that it is worth checking
>> gdbsx tool from Xen (xen/tools/debugger/gdbsx) and gdb protocol spec
>> (you could expose GDB interface from QEMU so it could be useful in HVM
>> case). Maybe crash protocol is very similar or even identical with GDB
>> protocol because a large part of crash is GDB itself.
I can see using gdbsx and gdb.  However I have found crash to be easier 
in lots of cases.  I could have used xg from here if I did not already 
have code based on xenctx.
> Ugh... I was in a hurry and forgot about final statement. Sorry for that.
No problem.
> So we could just use existing solutions if they are compatible with
> protocol used by crash.
>
> Daniel
The only existing solution that I know of is:

    xl dump-core <Domain> <filename>
    crash <filename>

But this way does require disk space, and the delay while writing the 
file.  For me it took ~2 minutes to write out a 3G core file.  I also do 
not see the current registers being saved in the core file.

    -Don Slutz

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listman.redhat.com/archives/crash-utility/attachments/20131118/d4767a24/attachment.htm>