On 09/03/2012 03:33 PM, Rusty Russell wrote: > Avi Kivity <avi@xxxxxxxxxx> writes: >> On 09/01/2012 03:35 PM, Rusty Russell wrote: >>> Passing an address in a struct is pretty bad, since it involves >>> compatibility wrappers. >> >> Right, some s390 thing. > > Err, no, i386 on x86-64, or ppc32 on ppc64, or arm on arm64.... > > Any time you put a pointer in a structure which is exposed to userspace, > you have to deal with this. Not is you pack the pointer in a __u64, which is what we do to preserve padding. Then it is only s390 which needs extra love. >>> I don't think that is what makes the API hard >>> to use. >> >> What is it then? I forgot what the original complaints/complainers were. > > I have no idea, since I didn't hear the complaints. But any non-fixed > size array has issues in C; there's not much we can do about it. > > x86 manages this fine for msrs, and I didn't have a problem using it for > my test programs. That's the limit of my experience, however. Another option is to use the size parameter from the ioctl. It just sits there doing nothing. -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
