[Fedora-xen] xen to kvm migration question

Avi Kivity avi at qumranet.com
Sat Jun 28 10:03:22 UTC 2008

Paul Wouters wrote:
> On Sat, 28 Jun 2008, Avi Kivity wrote:
>> qemu provides -kernel and -initrd flags for this; however I don't know if
>> virt-manager supports this.
> So with kvm i am still using qemu?

Yes; qemu provides emulation for the disk, network, and display devices, 

>> I find that a kernel+initrd inside the guest disk image is much more
>> maintainable; for example 'yum update kernel' will update your guest kernel
>> rather than having to copy files around.
> I find it much easier to mount fs images, then to go hunt for offset's for
> mount in disk images. 

Linux 2.6.26 supports partitionable loops devices, so you can loopback 
mount your disk image and then mount filesystems off /dev/loop0p1, 
/dev/loop0p2, etc.

> Also, during the xen2->xen3 and the non-PAE to PAE
> migrations, I liked my kernel and initrd separately :)

kvm supports pae and nonpae regardless of how the host kernel was 
compiled, so you can happily run an pae guest on top of a nonpae host.

Do not meddle in the internals of kernels, for they are subtle and quick to panic.

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