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[Xen-API] Xen save problem

Date: Sun, 9 Aug 2009 15:57:06 -0600

Delivery-date: Sun, 09 Aug 2009 14:57:16 -0700

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List-id: Discussion of API issues surrounding Xen <xen-api.lists.xensource.com>

Hi, everyone,

Thanks for your attention, I'm new to xen-devel and now have a weird problem. I implemented a very easy live save/migration program, which works OK for PV-domains. But for HVM domains, it only works for the first time.

So if I run the program for the first time:
myxm save vm-name test.dat
everything is OK. then after I restore the domain using:
xm restore test.dat

and run the program again:
myxm save vm-name test.dat

the program will output an error message : timed out waiting for qemu to switch buffers
which is due to line 218 in function qemu_flip_buffer, file xc_save.c

I debuged the program, and found that at first, xs_read function returns NULL but variable len is set to 7, then it tries to read again and timeout. I compared my own program with xen built-in xc_save.c, xc_domain_save.c files and found nothing. Do you have any idea why this happens, or is there any difference between a new HVM domain and a restored HVM domain ? I'm using xen-3.3 on ubuntu 8.10.

Thanks very much

Nathan Perry

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