Avi Kivity <avi@xxxxxxxxxx> wrote: > > We cannot get a complete snapshot without mmu_lock; if the guest faults on > > the Nth page during xchg'ing i = 1, 2, ... then the i = N alone will > > become newer. > > Ah, so there is no data corruption (missed dirty bits), just the display > is updated inconsistently? Yes, no data corruption and just a matter of ... feeling. The basic rule I wrote in the comment in this patch should be enough to not lose dirty bits. > I don't think we can get a consistent snapshot anyway, since the guest > can update the framebuffer while userspace is processing it. Yes, nothing will be broken. I was just not sure what the API should promise to the userspace. To some extent the inconsistency may be felt more than before. > Understood. I don't think we can get a consistent vga snapshot without > stopping the guest, and even then, it depends on how the guest updates > the framebuffer. OKay, I will not care about this from now. > > So I want to see how much improvement the proposed API can achieve. > > > > I thought this might be a good GSoC project but ... > > It may be too involved for GSoC, the issues are difficult. I am now checking QEMU code closely - rather readable than before! Though I can make experimental KVM patches for the student, just changing QEMU's live migration code seems to be difficult - but not sure now. Anyway, we should try this before deciding the new API: I mean if I cannot find anyone who want to try this, no need to be a student, I may do instead at some point. Takuya -- 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
