On Wed, May 28, 2014 at 10:56:45AM +0100, Marc Zyngier wrote: > On 25/05/14 16:34, Christoffer Dall wrote: > > On Tue, May 20, 2014 at 05:55:36PM +0100, Marc Zyngier wrote: > >> This patch series adds debug support, a key feature missing from the > >> KVM/arm64 port. > >> > >> The main idea is to keep track of whether the debug registers are > >> "dirty" (changed by the guest) or not. In this case, perform the usual > >> save/restore dance, for one run only. It means we only have a penalty > >> if a guest is actively using the debug registers. > >> > >> The amount of registers is properly frightening, but CPUs actually > >> only implement a subset of them. Also, there is a number of registers > >> we don't bother emulating (things having to do with external debug and > >> OSlock). > > > > What is the rationale about not having to deal with external debug and > > OSlock? > > External debug is when you actually plug a physical JTAG into the CPU. > OSlock is a way to prevent "other software" to play with the debug > registers. My understanding is that it is only useful in combination > with the external debug. > > In both case, implementing support for this is probably not worth the > effort, at least for the time being. > OK, can we document that somewhere clearly in the code then so we know how we can simply ignore those registers? Thanks, -Christoffer -- 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
