Il 20/08/2013 03:36, Alexey Kardashevskiy ha scritto: > Hm. Here we might have a problem like this is we decide to migrate from > QEMU with this patch running on modern kernel to QEMU without this patch > running on old kernel - for this we might want to be able to disable > "multi-tce" via machine options on newer kernels. Do we care enough to add > such a parameter or we just disable migration and that's it?
Upstream doesn't support migration to older QEMU. > This SandyBridge,enforce - what if the destination host running on old > kernel was run without this option - will the migration fail? The destination machine will not even start. >> But in this case, you do not need this because the hypercall works if >> emulated by QEMU. I like Alex's solution of making it universally >> available in the dtb. > > The solution would be good if we did not already have H_PUT_TCE accelerated > for emulated devices in the host kernel but we do have it. The question is also whether you consider pSeries support complete enough to be production ready---and until you have versioned machine types I would say you don't. If you still consider it somewhat experimental, I would do as Alex said: make newer QEMU on older KVM as slower, and that's it. Paolo
