64bit host requires 64bit guests?

[krobertson]

I'll admit I'm new to KVM, and Proxmox PVE is my first time using it (and I love it so far!).

I was going to be installing a Debian VM and was looking on their Wiki about KVM (http://wiki.debian.org/KVM) and it says:

Note, if the host OS is 64bit the guest OS has to be 64bit also, likewise for 32bit.

Is that true? I was kind of scratching my head, since I know Proxmox is 64bit, and the main VM I had been testing with was Ubuntu 8.10 32bit.

Was this the case before, but maybe changed in a more recent release?

 

[mangoo]

I'll admit I'm new to KVM, and Proxmox PVE is my first time using it (and I love it so far!).

I was going to be installing a Debian VM and was looking on their Wiki about KVM (http://wiki.debian.org/KVM) and it says:



Is that true? I was kind of scratching my head, since I know Proxmox is 64bit, and the main VM I had been testing with was Ubuntu 8.10 32bit.

Was this the case before, but maybe changed in a more recent release?

It is not true.
Of course you can run 32 bit guests on 64 bit hosts.

I corrected Debian wiki.

See also:

http://kvm.qumranet.com/kvmwiki/Guest_Support_Status

 

[krobertson]

Thanks! I'd forgotten about the guest status page, had just seen that line on the Debian wiki and was dumbfounded.

I'd googled some more and it looks like a 64bit host can only use the 64bit CPU type (x86_64), but the 64bit CPU type can run both 32bit and 64bit OSes. If that is correct, then it makes sense. Then the Debian wiki just sounds a bit out of context and doesn't really explain what it meant.

Thanks for correcting it!