On Tue, 2008-06-10 at 10:45 -0500, Hollis Blanchard wrote: > On Tue, 2008-06-10 at 10:33 -0500, Jerone Young wrote: > > On Tue, 2008-06-10 at 10:12 -0500, Hollis Blanchard wrote: > > > On Mon, 2008-06-09 at 18:56 -0500, Jerone Young wrote: > > > > > > If an IAC is matched before we enter the guest it will be caught host > > > > > > that catches it. > > > > > > > > > > But that won't happen because you've disabled MSR[DE]. > > > > > > > > Ah... you don't rember the whole imprecise interrupts ;-) . When MSR[DE] > > > > =0 and an IAC will go off but not at the exact address. This was fun > > > > figuring out. > > > > > > Right. Now, when will the deferred debug event fire, and who will handle > > > it? What can we do about that? > > > > If the debug registers are turned off before we disable MSR[DE], there > > will be no debug events at all. > > > > This is what I was talking about in my first couple of emails. If a > > debug event does go off and the host does not handle it, the only way to > > know is the dbsr register (and there is no way to save that off). So in > > the end it could end up going off in the guest. > > > > This is why I said you should not do host debugging if you want to do > > guest debugging at the sametime, as a work around for now. > > As I said before, forget host debugging! > > In fact, here is the exact text I sent to you on Friday, which you don't > appear to have read, in which I said exactly the same thing: > > On Fri, 2008-06-06 at 14:27 -0500, Hollis Blanchard wrote: > > On Fri, 2008-06-06 at 14:11 -0500, Jerone Young wrote: > > > That is an issue if you are using the IAC registers in the host > > also > at the same time. > > > > That is a totally separate issue. Imagine this in the host: > > > > 0xc0001000 load_guest_debug_registers: > > MSR[DE] = 0 > > IAC[0] = 0xc0001080 > > ... > > 0xc0001080 > > ... > > enter guest > > > > IAC1 matched. Now what happens? > > Please think about this scenario. Oh it hit me. So we *could* get an imprecise interrupt once we enable dbcr0. So do you want to enable dbcr0 once we enable MSR_DE in __kvmppc_vcpu_run() ? (In the future please just plainly state the issue..it saves emails..which I guess saves trees .. in someway). > > > I can clear the dbsr registers also when disabling the debug interrupts > > as a solution? > > I think you're on the right track, but what you propose here simply > won't affect the above scenario. > -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
