[RFC PATCH 17/17] KVM: PPC: Add an ioctl for userspace to select which platform to emulate
avi at redhat.com
Sun Jul 3 19:05:37 EST 2011
On 07/03/2011 12:00 PM, Alexander Graf wrote:
> >> }
> >> Otherwise we might write over data the user expected. And that logic that tells to copy_to_user how much data it actually takes to put all the information in is not there today and would have to be added. You can even verify that required_size with the ioctl passed size to make 100% sure user space is sane, but I'd claim that a feature bitmap is plenty of information to ensure that we're not doing something stupid.
> > I don't see why we have to caclulate something, then verify it against the correct answer.
> Ah, I think I'm grasping your idea. You'd simply truncate the resulting struct according to the size passed by the ioctl and call it a day. Well, that works too. User space simply wouldn't be able to know if all information actually fit into the struct, but I guess that's fine :).
Right. The idea is that if KVM_FLAG_BLAH implies a field
kvm_struct::blah, then either both are present in the headers, or none
error compiling committee.c: too many arguments to function
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