Re: [Xen-devel] [PATCH v4 03/16] libxl/arm: Generate static ACPI DSDT table

[Julien Grall <julien.grall@xxxxxxx>]

Hi Shannon,

On 31/08/16 07:37, Shannon Zhao wrote:
> On 2016/8/30 1:46, Julien Grall wrote:
> > On 16/08/2016 06:25, Shannon Zhao wrote:
> > > From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> > >
> > > It uses static DSDT table like the way x86 uses. Currently the DSDT
> > > table only contains processor device objects and it generates the
> > > maximal objects which so far is 128.
> > >
> > > Also only check iasl for aarch64 in configure since ACPI on ARM32 is not
> > > supported.
> > >
> > > Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> > > ---
> > >  tools/configure               |  2 +-
> > The file tools/configure should not be modified manually. Instead you
> > have to modify tools/configure.ac.
> >
> > You can regenerate tools/configure, you can call ./autegen.sh. However,
> > I would recommend you to not include the changes of configure and ask
> > the committer to regenerate. This is because we use always use the same
> > version of autotools to do generation in order to avoid spurious change.
> Ok, will fix.
>
> > > diff --git a/xen/include/public/arch-arm.h
> > > b/xen/include/public/arch-arm.h
> > > index 0afd654..008a2a0 100644
> > > --- a/xen/include/public/arch-arm.h
> > > +++ b/xen/include/public/arch-arm.h
> > > @@ -435,6 +435,9 @@ typedef uint64_t xen_callback_t;
> > >  #define GUEST_RAM_BANK_BASES   { GUEST_RAM0_BASE, GUEST_RAM1_BASE }
> > >  #define GUEST_RAM_BANK_SIZES   { GUEST_RAM0_SIZE, GUEST_RAM1_SIZE }
> > >
> > > +/* Current supported guest VCPUs */
> > > +#define GUEST_MAX_VCPUS 128
> > The number of vCPUS per guest supported depends whether Xen has been
> > built for ARM32 or ARM64.
> >
> > Also, because now we have two different place to define the number of
> > vCPUS (here and include/asm-arm/config.h) it might be possible to have
> > them differ by mistake.
> >
> > I am not sure how to avoid the 2 definitions, so I would add a
> > BUILD_BUG_ON in Xen to make sure that MAX_VIRT_CPUS is always <= to
> > GUEST_MAX_VCPUS.
> It has the below check. So could we just define GUEST_MAX_VCPUS as
> (GUEST_GICV3_GICR0_SIZE / GUEST_GICV3_RDIST_STRIDE)?
I much prefer hardcoding the value. It will be easier to catch any issue 
if we decide to use multiple re-distributor regions.
Stefano, do you have any opinions?

> BUILD_BUG_ON((GUEST_GICV3_GICR0_SIZE / GUEST_GICV3_RDIST_STRIDE) <
> MAX_VIRT_CPUS);
>
> Thanks,
Regards,

--
Julien Grall

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