On Mon, 14 Oct 2024 20:05:58 +0000
Salil Mehta <salil.me...@huawei.com> wrote:
> Hi Igor,
>
> > From: qemu-devel-bounces+salil.mehta=huawei....@nongnu.org <qemu-
> > devel-bounces+salil.mehta=huawei....@nongnu.org> On Behalf Of Igor
> > Mammedov
> > Sent: Monday, October 14, 2024 10:38 AM
> >
> > On Mon, 14 Oct 2024 16:52:55 +0800
> > maobibo <maob...@loongson.cn> wrote:
> >
> > > Hi Salil,
> > >
> > > When I debug cpu hotplug on LoongArch system, It reports error like this:
> > > ACPI BIOS Error (bug): Could not resolve symbol [\_SB.GED.CSCN],
> > > AE_NOT_FOUND
> > > ACPI Error: Aborting method \_SB.GED._EVT due to previous error
> > > (AE_NOT_FOUND)
> > > acpi-ged ACPI0013:00: IRQ method execution failed
> > >
> > >
> > > With this patch, GED CPU call method is "\\_SB.GED.CSCN", however in
> > > function build_cpus_aml(), its method name is "\\_SB.CPUS.CSCN".
> > > method = aml_method(event_handler_method, 0,
> > AML_NOTSERIALIZED);
> > > aml_append(method, aml_call0("\\_SB.CPUS." CPU_SCAN_METHOD));
> > > aml_append(table, method);
> > >
> > > It seems that CPU scanning method name is not consistent between
> > > function build_cpus_aml() and build_ged_aml().
> > >
> > > Regards
> > > Bibo Mao
> > >
> > > On 2024/7/23 下午6:59, Michael S. Tsirkin wrote:
> > > > From: Salil Mehta <salil.me...@huawei.com>
> > > >
> > > > OSPM evaluates _EVT method to map the event. The CPU hotplug
> > event
> > > > eventually results in start of the CPU scan. Scan figures out the
> > > > CPU and the kind of
> > > > event(plug/unplug) and notifies it back to the guest. Update the GED
> > > > AML _EVT method with the call to method \\_SB.CPUS.CSCN (via
> > > > \\_SB.GED.CSCN)
> > > >
> > > > Architecture specific code [1] might initialize its CPUs AML code by
> > > > calling common function build_cpus_aml() like below for ARM:
> > > >
> > > > build_cpus_aml(scope, ms, opts, xx_madt_cpu_entry,
> > memmap[VIRT_CPUHP_ACPI].base,
> > > > "\\_SB", "\\_SB.GED.CSCN", AML_SYSTEM_MEMORY);
> >
> > it should be \\_SB.CPUS.CSCN
>
>
> I guess we are getting back to where we started then?
>
> https://lore.kernel.org/qemu-devel/20240706162845.3baf5...@imammedo.users.ipa.redhat.com/
>
Indeed, CSCN in name had me confused,
perhaps it would be better to rename that something else.
maybe something like s/_SB.GED.CSCN/_SB.GED.ECPU/
> Excerpt from above discussion and your suggestion:
> [...]
>
> I don't particularly like exposing cpu hotplug internals for outside code
> and then making that code do plumbing hoping that nothing will explode
> in the future.
>
> build_cpus_aml() takes event_handler_method to create a method that
> can be called by platform. What I suggest is to call that method here
> instead of trying to expose CPU hotplug internals and manually building
> call path here.
> aka:
> build_cpus_aml(event_handler_method = PATH_TO_GED_DEVICE.CSCN)
> and then call here
> aml_append(if_ctx, aml_call0(CSCN));
> which will call CSCN in GED scope, that was be populated by
> build_cpus_aml() to do cpu scan properly without need to expose
> cpu hotplug internal names and then trying to fixup conflicts caused by that.
>
> PS:
> we should do the same for memory hotplug, we see in context above
>
> [...]
>
>
> Solution:
> I've avoided above error in different way and keeping exactly what you
> suggested \_SB.PATH_TO_GED_DEVICE.CSCN i.e. \_SB.GED.CSCN
> Please have a look:
>
> https://lore.kernel.org/qemu-devel/20241009031815.250096-16-salil.me...@huawei.com/
>
> Many thanks!
>
>
> Best regards
> Salil.
>
