Re: [Xen-devel] [RFC PATCH V2 2/4] Tool/ACPI: DSDT extension to support more vcpus

[Julien Grall <julien.grall@xxxxxxx>]

Hi,

Sorry for the late reply.

On 04/09/17 10:05, Roger Pau Monné wrote:
> On Mon, Sep 04, 2017 at 11:07:14AM +0800, Lan Tianyu wrote:
> > On 2017年09月01日 17:41, Roger Pau Monné wrote:
> > > On Fri, Sep 01, 2017 at 10:54:02AM +0800, Lan Tianyu wrote:
> > > > On 2017年08月31日 23:38, Roger Pau Monné wrote:
> > > > > On Thu, Aug 31, 2017 at 01:01:47AM -0400, Lan Tianyu wrote:
> > > > > > This patch is to change DSDT table for processor object to support >128 vcpus
> > > > > > accroding to ACPI spec 8.4 Declaring Processors
> > > > > >
> > > > > > Signed-off-by: Lan Tianyu <tianyu.lan@xxxxxxxxx>
> > > > > > ---
> > > > > >   tools/libacpi/mk_dsdt.c | 18 ++++++++++++------
> > > > > >   1 file changed, 12 insertions(+), 6 deletions(-)
> > > > > >
> > > > > > diff --git a/tools/libacpi/mk_dsdt.c b/tools/libacpi/mk_dsdt.c
> > > > > > index 2daf32c..6c4c325 100644
> > > > > > --- a/tools/libacpi/mk_dsdt.c
> > > > > > +++ b/tools/libacpi/mk_dsdt.c
> > > > > > @@ -24,6 +24,8 @@
> > > > > >   #include <xen/arch-arm.h>
> > > > > >   #endif
> > > > > >   
> > > > > > +#define CPU_NAME_FMT      "P%.03X"
> > > > > > +
> > > > > >   static unsigned int indent_level;
> > > > > >   static bool debug = false;
> > > > > >   
> > > > > > @@ -196,10 +198,14 @@ int main(int argc, char **argv)
> > > > > >       /* Define processor objects and control methods. */
> > > > > >       for ( cpu = 0; cpu < max_cpus; cpu++)
> > > > > >       {
> > > > > > -        push_block("Processor", "PR%02X, %d, 0x0000b010, 0x06", cpu, cpu);
> > > > > > +        unsigned int apic_id = cpu * 2;
> > > > > This is fragile, ideally there should be a single point where the APIC
> > > > > ID is calculated. Although there are already two places where the APIC
> > > > > ID is calculated, in hvmloader and libxl.
> > > > >
> > > > > And I'm not sure how to use any of those here in order to avoid
> > > > > introducing a third one.
> > > > The mk_dsdt is independent tool to build dsdt table. It wasn't linked
> > > > with libxl and hvmloader. We can't reuse old function to do that.
> > > >
> > > > But I think we may introduce a new LAPIC_ID(vcpu) in the arch head
> > > > file(i.e, #include <xen/arch-x86/xen.h>) and replace old ones.
> > > There's already a LAPIC_ID macro in hvmloader headers which should be
> > > placed somewhere suitable.
> > Yes, this is what I mentioned.
> Jan has expressed some concerns with removing the hook, see:
>
> <59A94E320200007800176754@xxxxxxxxxxxxxxxxxxxxxxx>
>
> > > What about removing the lapic_id hook from
> > > acpi_config and placing the LAPIC_ID macro in the libacpi.h header?
> > I think this should be ARCH specific. I am not sure whether ARM follows
> > rule of "apic_id = vcpu_id *2".
> >
> > Julien, could you give some inputs? Thanks.
> AFAIK ARM doesn't have a local APIC, so there are no xAPIC/x2APIC
> entries in the ARM MADT.
That's correct. ARM does not use xAPIC/x2APIC tables.

Cheers,

--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel