> From: Stefan Hajnoczi [stefanha@xxxxxxxxx] > Sent: 10 November 2010 12:47 > To: Prasad Joshi > Cc: Keqin Hong; kvm@xxxxxxxxxxxxxxx > Subject: Re: Unable to start VM using COWed image > On Wed, Nov 10, 2010 at 12:40 PM, Prasad Joshi <P.G.Joshi@xxxxxxxxxxxxxxxxxxxxx> wrote: >> From: Stefan Hajnoczi [stefanha@xxxxxxxxx] >> Sent: 10 November 2010 11:12 >> To: Prasad Joshi >> Cc: Keqin Hong; kvm@xxxxxxxxxxxxxxx >> Subject: Re: Unable to start VM using COWed image > > On Wed, Nov 10, 2010 at 10:08 AM, Prasad Joshi > <P.G.Joshi@xxxxxxxxxxxxxxxxxxxxx> wrote: >> Where can I get the code of the qemu-kvm program? >> I cloned the qemu-lvm git repository and compiled the code. But it looks like qemu-kvm program is not part of this code.-- > >> qemu-kvm.git contains the qemu-kvm codebase but the binary is built in >> x86_64-softmmu/qemu-system-x86_64. Distro packages typically rename >> it to qemu-kvm. > > Thanks Stefan for your reply. > > I guess you pointed out the problem in the first mail. QEMU places a restriction on location of the COWed file. The source image and COWed image should be in the same drectory. > > In my case the source image was in directory /var/lib/libvirt/images/ and the COWed image was in /home/prasad/Virtual directory. > While debuging the source code using gdb I realized this limitation. It would be good to fix this problem. I will see if I can solve this problem. > This behavior is a feature. You chose to use a relative backing file > path when you used qemu-img create -b <relative-path>. > If you want an absolute path you need to use qemu-img create -b > /home/prasad/Virtual/... (i.e. specify an absolute path instead of a > relative path). Oh I see. I am such a stupid. ha ha ha ha Thanks a lot for letting me know. It worked after using absolute paths. Gr8 Thanks a lot. >> One more question on the same lines, >> How does QEMU detect the file is COWed and the name of the file (not whole path) from it is COWed? > COW support comes from the image file format that you choose. A qcow > file is not just a raw image file like the kind you can dd from a real > disk. Instead it has its own file format including a header and > metadata for tracking allocated space. The header contains the name > of the backing file. > Stefan -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
