On Wed, 2011-01-26 at 17:14 +0200, Avi Kivity wrote: > On 01/26/2011 02:14 PM, Glauber Costa wrote: > > On Wed, 2011-01-26 at 13:12 +0200, Avi Kivity wrote: > > > On 01/24/2011 08:06 PM, Glauber Costa wrote: > > > > KVM, which stands for KVM Virtual Memory (I wanted to call it KVM Virtual Mojito), > > > > is a piece of shared memory that is visible to both the hypervisor and the guest > > > > kernel - but not the guest userspace. > > > > > > > > The basic idea is that the guest can tell the hypervisor about a specific > > > > piece of memory, and what it expects to find in there. This is a generic > > > > abstraction, that goes to userspace (qemu) if KVM (the hypervisor) can't > > > > handle a specific request, thus giving us flexibility in some features > > > > in the future. > > > > > > > > KVM (The hypervisor) can change the contents of this piece of memory at > > > > will. This works well with paravirtual information, and hopefully > > > > normal guest memory - like last update time for the watchdog, for > > > > instance. > > > > > > > > This patch contains the header part of the userspace communication implementation. > > > > Userspace can query the presence/absence of this feature in the normal way. > > > > It also tells the hypervisor that it is capable of handling - in whatever > > > > way it chooses, registrations that the hypervisor does not know how to. > > > > In x86, only user so far, this mechanism is implemented as generic userspace > > > > msr exit, that could theorectically be used to implement msr-handling in > > > > userspace. > > > > > > > > I am keeping the headers separate to facilitate backports to people > > > > who wants to backport the kernel part but not the hypervisor, or the other way around. > > > > > > > > > > Again the protocol is not specified. How about starting from > > > Documentation/kvm/api.txt so we don't have to guess? > > I will do that in the next version, if the idea is not shoot up > > completely. > > For some reason people write the code first and the documentation as an > afterthought. If you switch the order, you can get a high level review > first, followed by a low-level code review once the high level details > are agreed. Of course it's hard to do major changes this way, since the > API often evolves while writing the code. Thing is, processor runs code, not english. So I guess people write code first at least to know what works vs what not works before writing a potentially beautiful-but-only-theoretical novel. Rest assured, I don't plan to push for merges of any feature before providing docs. -- 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
