Re: [PULL 33/41] KVM: PPC: Book3S: Move KVM_REG_PPC_WORT to an unused register number

Paolo Bonzini
2014-05-30T16:03:10Z

Il 30/05/2014 17:58, Alexander Graf ha scritto:
>>
>> Would new userspace with old kernel be able to detect that POWER8
>> support isn't quite complete?
>
> It couldn't, no. It would try to run a guest - if it happens to work
> we're lucky ;).

That's why I'm considering a revert.

> Even then the only thing that would remotely be affected
> by that one_reg rename is live migration (which just got a few more
> fixes in this pull request).

Doesn't "info cpus" also do get/set one_reg? What happens if it returns
EINVAL? Also, reset should certainly try to write all registers, what
happens if one is missed.

Beyond the particular case of WORT, I'd just like to point out that
uapi/ changes need even more scrutiny from maintainers than usual. I
don't know exactly what checks Linus makes in my pull requests, but
uapi/ is at the top of the list of things he might look at, right after
the diffstat. :)

Paolo