On Thu, Nov 29, 2018 at 04:09:47PM +0100, Andrew Jones wrote:
> On Thu, Nov 29, 2018 at 03:59:42PM +0100, Samuel Ortiz wrote:
> > On Thu, Nov 29, 2018 at 03:42:43PM +0100, Andrew Jones wrote:
> > > On Thu, Nov 29, 2018 at 02:24:26PM +0100, Samuel Ortiz wrote:
> > > > We add the ability to build legacy or current RSDP tables, based on the
> > > > AcpiRsdpData revision field passed to build_rsdp().
> > > > Although arm/virt only uses RSDP v2, adding that capability to
> > > > build_rsdp will allow us to share the RSDP build code between ARM and
> > > > x86.
> > > >
> > > > Signed-off-by: Samuel Ortiz <sa...@linux.intel.com>
> > > > ---
> > > > hw/arm/virt-acpi-build.c | 37 ++++++++++++++++++++++++++-----------
> > > > 1 file changed, 26 insertions(+), 11 deletions(-)
> > > >
> > > > diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
> > > > index 4782aea4fe..e1338b6f5a 100644
> > > > --- a/hw/arm/virt-acpi-build.c
> > > > +++ b/hw/arm/virt-acpi-build.c
> > > > @@ -378,23 +378,38 @@ build_rsdp(GArray *tbl, BIOSLinker *linker,
> > > > AcpiRsdpData *rsdp_data)
> > > > g_array_append_vals(tbl, rsdp_data->oem_id, 6); /* OEMID */
> > > > build_append_int_noprefix(tbl, rsdp_data->revision, 1); /*
> > > > Revision */
> > > > build_append_int_noprefix(tbl, 0, 4); /* RsdtAddress */
> > > > - build_append_int_noprefix(tbl, 36, 4); /* Length */
> > > > -
> > > > - /* XSDT address to be filled by guest linker */
> > > > - build_append_int_noprefix(tbl, 0, 8); /* XsdtAddress */
> > > > - bios_linker_loader_add_pointer(linker, ACPI_BUILD_RSDP_FILE,
> > > > - 24, 8,
> > > > - ACPI_BUILD_TABLE_FILE,
> > > > - *rsdp_data->xsdt_tbl_offset);
> > > > -
> > > > - build_append_int_noprefix(tbl, 0, 1); /* Extended Checksum */
> > > > - build_append_int_noprefix(tbl, 0, 3); /* Reserved */
> > > > + if (rsdp_data->rsdt_tbl_offset) {
> > >
> > > I see why a pointer was used now. Using a pointer ensures a zero
> > > offset won't fail this test. However the test could be replaced with
> > > rsdp_data->revision == 0.
> > >
> > > > + /* RSDT address to be filled by guest linker */
> > > > + bios_linker_loader_add_pointer(linker,
> > > > + ACPI_BUILD_RSDP_FILE, 16, 4,
> > > > + ACPI_BUILD_TABLE_FILE,
> > > > + *rsdp_data->rsdt_tbl_offset);
> > > > + }
> > > >
> > > > /* Checksum to be filled by guest linker */
> > > > bios_linker_loader_add_checksum(linker, ACPI_BUILD_RSDP_FILE,
> > > > 0, 20, /* ACPI rev 1.0 RSDP size */
> > > > 8);
> > > >
> > > > + if (rsdp_data->revision == 0) {
> > > > + /* ACPI 1.0 RSDP, we're done */
> > > > + return;
> > > > + }
> > > > +
> > > > + /* The RSDP revision is 2 and later, we must have an XSDT pointer
> > > > */
> > > > + g_assert(rsdp_data->xsdt_tbl_offset != NULL);
> > >
> > > So here's the justification for the pointers. We sanity check the callers.
> > We could sanity check the callers without pointers as well, I don't
> > think there's a strong advantage for pointers here, except consistence.
> >
> >
> > > We're missing the (rsdp_data->revision == 0 && rsdp_data->rsdt_tbl_offset)
> > > sanity check though.
> > I think there's nothing preventing a caller to include both rsdt and
> > xsdt if it wants to be able to run on both < 2.0 and 2.0+ platforms with
> > the same table. So if rsdt is set we should add it, regardless of the
> > revision.
>
> True, but if revision is zero, then we *must* have it. Otherwise we'll
> silently return from this function with neither an rsdt nor xsdt linked.
Correct, thanks. With v3 I'm adding a small piece of code at the start
of build_rsdp() that checks for valid rsdt and xsdt pointers (for rev 0
and 2, respectively).
Cheers,
Samuel.
