Avi Kivity wrote: > Let's start with '-cpu host' as 'cpu host-cpuid' and implement '-cpu > host-os' on the first bug report? I have a feeling we won't ever see it.
I have a feeling you won't ever see it either, but not because it's a missing feature. Instead, I think a very small number of users will spend hours frustrated that some obscure guest doesn't work properly on their obscure x86 hardware, then they will learn that they should not use "-cpuid host" for that guest on that hardware, even though it works fine with other guests, and then their problem will be solved (albeit at a cost), and seen as such an obscure combination that it might never be reported to Qemu developers. In other words, host-os is what _I'd_ implement because I care too much about the poor obscure users and think it's the safe option, but I'm not doing the implementing here ;-) If you are curious what the differences are, do this in a current Linux source tree: egrep -R '(set|clear)_bit\(X86_FEATURE' arch/{i386,x86_64}/kernel -- Jamie