[Xen-devel] xen save problem

["Nathan" <nath.perry@xxxxxxxxx>]

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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