On 25/06/2018 21:51, Eduardo Habkost wrote: >> Before that we should ask what the benefit is in changing the default >> for qemu-system-*. Nobody is using it in practice to start QEMU with >> KVM enabled... > > How can you be sure? If qemu-system-* is installed with KVM > compiled in, libvirt will probe it using > "-machine none,accel=kvm:tcg" and run the VM using > "-machine $MACHINE,accel=kvm".
Right, that needs to be qualified with "without libvirt". > In either case, I'm not arguing (yet) for changing the default > upstream. I'm just arguing for upstream QEMU to not make any > promises about the default. It would be a guest ABI breakage for TCG guests, so it would only apply to new machine types. I don't think it's worth the complication. BTW, another thing that needs documenting is ABI promises for HAX and WHPX. Both do not support -cpu in any meaningful way, at least WHPX installs a migration blocker. Paolo
