On Fri, Sep 6, 2013 at 4:04 PM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote: > On 2013-09-06 11:24, Alexander Graf wrote: >> >> On 06.09.2013, at 12:05, Anup Patel wrote: >> >>> On Fri, Sep 6, 2013 at 2:24 PM, Alexander Graf <agraf@xxxxxxx> wrote: >>>> >>>> >>>> On 06.09.2013, at 09:44, Anup Patel wrote: > > > [...] > > >>>>> Another advantage I saw in extending KVM_ARM_VCPU_INIT ioctl is >>>>> backward compatibility with current semantics. In other words, this >>>>> patch >>>>> does not break current KVMTOOL/QEMU and they can implement >>>>> "-cpu host" whenever they wish without using any additional ioctl. >>>> >>>> >>>> It's the opposite actually. By making the ioctl parameter in/out >>>> direction you change the ioctl number, breaking the ABI, no? >>> >>> >>> Originally the ioctl was only "in" and so we are preserving the "in" >>> semantics. Thats why it is semantically backward compatible. >> >> >> Great. So now we have an ioctl that says it's "in" in its ioctl >> descriptor, but really it's in/out. This really only works by accident >> because nobody is filtering the direction today. >> >> Nack. > > > Agreed. We don't break the ABI, we don't try to fool the kernel. Please. We are not breaking the ABI here and also not trying to fool the kernel. > > There's been previous suggestions on how to implement this feature, please > consider them. I am not convinced about how is this approach not better. > > M. > -- > Fast, cheap, reliable. Pick two. --Anup _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm
