Re: [Xen-devel] [PATCH v2 16/17] libxc/xc_dom_arm: Copy ACPI tables to guest space

[Julien Grall <julien.grall@xxxxxxx>]

Hi Stefano,

On 05/07/16 18:13, Stefano Stabellini wrote:
> On Thu, 23 Jun 2016, Julien Grall wrote:
> > On 23/06/2016 04:17, Shannon Zhao wrote:
> > > From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> > >
> > > Copy all the ACPI tables to guest space so that UEFI or guest could
> > > access them.
> > >
> > > Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> > > ---
> > >   tools/libxc/xc_dom_arm.c | 51
> > > ++++++++++++++++++++++++++++++++++++++++++++++++
> > >   1 file changed, 51 insertions(+)
> > >
> > > diff --git a/tools/libxc/xc_dom_arm.c b/tools/libxc/xc_dom_arm.c
> > > index 64a8b67..6a0a5b7 100644
> > > --- a/tools/libxc/xc_dom_arm.c
> > > +++ b/tools/libxc/xc_dom_arm.c
> > > @@ -63,6 +63,47 @@ static int setup_pgtables_arm(struct xc_dom_image *dom)
> > >
> > >   /* ------------------------------------------------------------------------
> > > */
> > >
> > > +static int xc_dom_copy_acpi(struct xc_dom_image *dom)
> > > +{
> > > +    int rc, i;
> > > +    uint32_t pages_num = ROUNDUP(dom->acpitable_size, XC_PAGE_SHIFT) >>
> > > +                         XC_PAGE_SHIFT;
> > > +    const xen_pfn_t base = GUEST_ACPI_BASE >> XC_PAGE_SHIFT;
> > > +    xen_pfn_t *p2m;
> > > +    void *acpi_pages;
> > > +
> > > +    p2m = malloc(pages_num * sizeof(*p2m));
> > > +    for (i = 0; i < pages_num; i++)
> > > +        p2m[i] = base + i;
> > > +
> > > +    rc = xc_domain_populate_physmap_exact(dom->xch, dom->guest_domid,
> > > +                                          pages_num, 0, 0, p2m);
> > Hmmmm... it looks like this is working because libxl is setting the maximum
> > size of the domain with some slack (1MB). However, I guess the slack was for
> > something else. Wei, Stefano, Ian, can you confirm?
> If I recall correctly, the slack is a magic value coming from the
> ancient history of toolstacks.
Does it mean we would need to update the slack to take into account the 
ACPI blob?
Cheers,

--
Julien Grall

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