help for snapshot

help for snapshot

[高强]

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Hi,alls

I'm modifying the source code of xen-4.4.1. Specifically, I'm modifying the
memory copy part of snapshot. I first put all memory pages to write
protection, and then rewrite the write protection exception part of the
code. After capture the exception  then save the memory page , and all
memory page copy is complete, call the function xenaccess_teardown(xch,
xenaccess), but there is a mistake:

libxl: error: libxl_utils.c:396:libxl_read_exactly: file/stream truncated
reading ipc msg header from domain 3 save/restore helper stdout pipe
libxl: error: libxl_exec.c:129:libxl_report_child_exitstatus: domain 3
save/restore helper [-1] died due to fatal signal Segmentation fault (core
dumped)
Failed to save domain, resuming domain

Has anyone ever meet this kind of problem, and who can tell me the cause of
the error.

Thanks

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Re: help for snapshot

[Gohar Irfan]

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I'm also working on a similar thing - can you please tell me how you copy
the memory pages from one part of the memory to another?

On Tue, Oct 13, 2015 at 10:04 AM 高强 <mrgao.buffoon@gmail.com> wrote:

> Hi,alls
>
> I'm modifying the source code of xen-4.4.1. Specifically, I'm modifying
> the memory copy part of snapshot. I first put all memory pages to write
> protection, and then rewrite the write protection exception part of the
> code. After capture the exception  then save the memory page , and all
> memory page copy is complete, call the function xenaccess_teardown(xch,
> xenaccess), but there is a mistake:
>
> libxl: error: libxl_utils.c:396:libxl_read_exactly: file/stream truncated
> reading ipc msg header from domain 3 save/restore helper stdout pipe
> libxl: error: libxl_exec.c:129:libxl_report_child_exitstatus: domain 3
> save/restore helper [-1] died due to fatal signal Segmentation fault (core
> dumped)
> Failed to save domain, resuming domain
>
> Has anyone ever meet this kind of problem, and who can tell me the cause
> of the error.
>
> Thanks
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel
>

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Re: help for snapshot

[高强]

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I'm modifying the source code of snapshot,in the function xc_domain_save()
of xc_domain_save.c,through calling wrexact() to copy the memory pages to
the local dist.

I'm not sure if it is the answer you wang.

2015-10-13 13:49 GMT+08:00 Gohar Irfan <goharirfan94@gmail.com>:

> I'm also working on a similar thing - can you please tell me how you copy
> the memory pages from one part of the memory to another?
>
> On Tue, Oct 13, 2015 at 10:04 AM 高强 <mrgao.buffoon@gmail.com> wrote:
>
>> Hi,alls
>>
>> I'm modifying the source code of xen-4.4.1. Specifically, I'm modifying
>> the memory copy part of snapshot. I first put all memory pages to write
>> protection, and then rewrite the write protection exception part of the
>> code. After capture the exception  then save the memory page , and all
>> memory page copy is complete, call the function xenaccess_teardown(xch,
>> xenaccess), but there is a mistake:
>>
>> libxl: error: libxl_utils.c:396:libxl_read_exactly: file/stream truncated
>> reading ipc msg header from domain 3 save/restore helper stdout pipe
>> libxl: error: libxl_exec.c:129:libxl_report_child_exitstatus: domain 3
>> save/restore helper [-1] died due to fatal signal Segmentation fault (core
>> dumped)
>> Failed to save domain, resuming domain
>>
>> Has anyone ever meet this kind of problem, and who can tell me the cause
>> of the error.
>>
>> Thanks
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@lists.xen.org
>> http://lists.xen.org/xen-devel
>>
>

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Re: help for snapshot

[Ian Campbell]

On Tue, 2015-10-13 at 09:18 +0800, 高强 wrote:
> Hi,alls
> 
> I'm modifying the source code of xen-4.4.1. Specifically, I'm modifying
> the memory copy part of snapshot. I first put all memory pages to write
> protection, and then rewrite the write protection exception part of the
> code. After capture the exception  then save the memory page , and all
> memory page copy is complete, call the function xenaccess_teardown(xch,
> xenaccess), but there is a mistake:
> 
> libxl: error: libxl_utils.c:396:libxl_read_exactly: file/stream truncated
> reading ipc msg header from domain 3 save/restore helper stdout pipe
> libxl: error: libxl_exec.c:129:libxl_report_child_exitstatus: domain 3
> save/restore helper [-1] died due to fatal signal Segmentation fault
> (core dumped)
> Failed to save domain, resuming domain
> 
> Has anyone ever meet this kind of problem, and who can tell me the cause
> of the error.

Without knowing exactly what you have changed, probably not.

Ian.


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help for snapshot

[高强]

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Hi,alls.

in xen-4.4.1/tools/libxc/xc_domain_save.c,the function
xc_domain_save(),there are two function xc_report_progress_start()
and xc_report_progress_step().And so as xc_domain_restore().

I don't know the function of these two functions,has anyone can tell me?

thanks

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help for snapshot

[高强]

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Hi,alls

I know the snapshot of xen-4.4.1 is through the function xc_domain_save()
to achieve.But I want to know from executing the command "xl save" to
executing the function xc_domain_save(),how it is call.

Has anybody can tell me the call relationship from python to C about
snapshot?

Thanks

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help for snapshot

[高强]

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Hi,alls

I 'm modifying the source code of snapshot in xen-4.4.1. I know the memory
copy and cpu state copy are all in xc_domain_save.c--xc_domain_save().

But I don't sure where is the device state copy. Who can tell me the
position of device copy in source code.

Thanks

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Re: help for snapshot

[Wei Liu]

On Wed, Oct 21, 2015 at 11:06:07AM +0800, 高强 wrote:
> Hi,alls
> 
> I 'm modifying the source code of snapshot in xen-4.4.1. I know the memory
> copy and cpu state copy are all in xc_domain_save.c--xc_domain_save().
> 
> But I don't sure where is the device state copy. Who can tell me the
> position of device copy in source code.
> 

Please try using grep to search for relevant strings inside
tools/libx{c,l} and ask more specific questions.

http://wiki.xenproject.org/wiki/Asking_Developer_Questions

Wei.


> Thanks

> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel


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Re: help for snapshot

[Ian Campbell]

On Wed, 2015-10-21 at 11:06 +0800, 高强 wrote:
> Hi,alls
> 
> I 'm modifying the source code of snapshot in xen-4.4.1.

That is now 3 Xen releases ago.

I suggest that if you want help with new developments you should target the
master branch in xen.git (which is targetted becoming 4.7) or as an
absolute minimum the latest release branch (stable-4.6).

A lot has changed WRT migration and related technologies in the 4.6
release, working on new functionality for such things against 4.4 at this
is not of much interest to the community I'm afraid.

Ian.


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Re: help for snapshot

[Dario Faggioli]

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On Wed, 2015-10-21 at 10:07 +0100, Ian Campbell wrote:

> I suggest that if you want help with new developments you should
> target the
> master branch in xen.git (which is targetted becoming 4.7) or as an
> absolute minimum the latest release branch (stable-4.6).
> 
> A lot has changed WRT migration and related technologies in the 4.6
> release, working on new functionality for such things against 4.4 at
> this
> is not of much interest to the community I'm afraid.
> 
Not to mention that the new migration code you'll find in the code
branches that Ian mentioned, is most likely going to be better
structured and easier to understand and modify.

Regards,
Dario
-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)


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