[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v7 16/32] xen/x86: allow disabling the pmtimer
El 03/11/15 a les 13.41, Jan Beulich ha escrit: >>>> On 03.11.15 at 11:57, <andrew.cooper3@xxxxxxxxxx> wrote: >> On 03/11/15 07:21, Jan Beulich wrote: >>>>>> On 30.10.15 at 16:36, <andrew.cooper3@xxxxxxxxxx> wrote: >>>> On 30/10/15 13:16, Jan Beulich wrote: >>>>>>>> On 30.10.15 at 13:50, <roger.pau@xxxxxxxxxx> wrote: >>>>>> El 14/10/15 a les 16.37, Jan Beulich ha escrit: >>>>>>>>>> On 02.10.15 at 17:48, <roger.pau@xxxxxxxxxx> wrote: >>>>>>>> Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx> >>>>>>>> Cc: Jan Beulich <jbeulich@xxxxxxxx> >>>>>>>> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> >>>>>>>> --- >>>>>>>> Changes since v6: >>>>>>>> - Return ENODEV in pmtimer_load if the timer is disabled. >>>>>>>> - hvm_acpi_power_button and hvm_acpi_sleep_button become noops if the >>>>>>>> pmtimer is disabled. >>>>>>> But how are those two features connected? I don't think you can >>>>>>> assume absence of a PM block just because there's no PM timer. >>>>>>> Or if you want to tie them together for now, the predicate needs >>>>>>> to be renamed. >>>>>>> >>>>>>>> - Return ENODEV if pmtimer_change_ioport is called with the pmtimer >>>>>>>> disabled. >>>>>>> Same here. >>>>>> What about changing XEN_X86_EMU_PMTIMER into XEN_X86_EMU_PM and this >>>>>> flags disables all PM stuff? >>>>> Ah, right, that's a reasonable option. >>>> It still might be a nice idea to split them in two, given future work. >>>> >>>> To support hotplug properly (cpu, ram and pci), Xen needs to inject >>>> GPEs, which comes from part of the PM infrastructure. To support PCI >>>> devices in the future without the whole PM infrastructure, it would be >>>> nice to keep the split. >>> Coming back to this - I'm not sure: The hotplug aspect as you >>> mention it should matter for Dom0 only. DomU could (and perhaps >>> should) use a PV interface instead. >> >> I disagree. >> >> All PVH guests should use the same mechanism; making a split between >> dom0 and domU will only make our lives harder. >> >> Where reasonable, we should follow what happens on native; one of the >> underlying points of PVH is to have less of an impact on the guest >> side. In some cases it is indeed nasty, but has the advantage of being >> well understood. > > What meaning would ACPI have to a PVH DomU? > >>> So I'd like to suggest quite the opposite: Don't call the thing PM, >>> but make it more general and call it ACPI. And instead of >>> separating HPET, we might have this fall under ACPI as well, or >>> we might have a second TIMER flag, requiring both to be set >>> for there to be a HPET and PMTMR. This leaves open the option >>> of Dom0 getting ACPI enabled (despite this then being "real", >>> not emulated ACPI), but TIMER left off. >> >> An HPET can exist independently of other features such as ACPI. It >> should have its own option. > > Without ACPI there's no defined way to discover it. Doing what > Linux does - applying chipset knowledge - won't work on PVH either, > because there's no emulated chipset. Which would leave scanning > physical memory, but if there is none, none can be found. > >> +1 to having an ACPI option, but as indicated above, I expect it to be >> used in the longterm even for domU. > > Again - why and how? I think that at this point in the design it's not so important to have all the XEN_X86_EMU_* properly defined. This is not a public interface, so we can expand/reduce them whenever we want. Would it be fine, for the time being to just have a XEN_X86_EMU_PM and control both the PM and the PMTMR? Roger. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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