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/
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.
