On Mon, Nov 20, 2023 at 4:24 AM Dhaval Sharma <dha...@rivosinc.com> wrote:
>
> As per ACPI Spec 6.5+ Table 5-9 if xDSDT is avaialble,
nit: available
> it should be used first. Handle required flow when xDSDT
> is abscent or present.
nit: absent
Separate nit: Please update the patch's subject to something more
descriptive. "Fix issue with ..." is really generic and useless for
anyone reading the log/blame.
Maybe something like "MdeModulePkg/AcpiTableDxe: Prefer xDSDT over
DSDT when installing tables"?
>
> Test: Tested on RISCV64 Qemu platform with xDSDT and booted to
> linux kernel.
>
> Cc: Liming Gao <gaolim...@byosoft.com.cn>
> Cc: Zhiguang Liu <zhiguang....@intel.com>
> Cc: Dandan Bi <dandan...@intel.com>
> Signed-off-by: Dhaval Sharma <dha...@rivosinc.com>
> ---
>
> Notes:
> v2:
> - Added proper indentation for else if
>
> MdeModulePkg/Universal/Acpi/AcpiTableDxe/AcpiTableProtocol.c | 22
> +++++++++++++-------
> 1 file changed, 15 insertions(+), 7 deletions(-)
>
> diff --git a/MdeModulePkg/Universal/Acpi/AcpiTableDxe/AcpiTableProtocol.c
> b/MdeModulePkg/Universal/Acpi/AcpiTableDxe/AcpiTableProtocol.c
> index e09bc9b704f5..ead8376177c9 100644
> --- a/MdeModulePkg/Universal/Acpi/AcpiTableDxe/AcpiTableProtocol.c
> +++ b/MdeModulePkg/Universal/Acpi/AcpiTableDxe/AcpiTableProtocol.c
> @@ -1892,14 +1892,22 @@ InstallAcpiTableFromHob (
> }
> }
>
> - if (((EFI_ACPI_3_0_FIXED_ACPI_DESCRIPTION_TABLE *)ChildTable)->Dsdt
> != 0) {
> + //
> + // First check if xDSDT is available that is preferred as per
nit: available, as that is preferred...
> + // ACPI Spec 6.5+ Table 5-9 X_DSDT definition
> + //
> + if (((EFI_ACPI_3_0_FIXED_ACPI_DESCRIPTION_TABLE *)ChildTable)->XDsdt
> != 0) {
> + TableToInstall = (VOID
> *)(UINTN)((EFI_ACPI_3_0_FIXED_ACPI_DESCRIPTION_TABLE *)ChildTable)->XDsdt;
(+CC Gerd for qemu)
Is it possible that XDsdt may come filled out with a > 32-bit address
on 32-bit platforms/builds? In other words, is truncation of the
address a problem here? Assuming all of these tables are coming from
qemu + OvmfPkg/AcpiPlatformDxe, that is. I would not expect real
platforms to ever do such a thing.
For what it's worth, I checked the spec, and it clearly mentions that
the *OSPM* must ignore DSDT over X_DSDT. But we're not OSPM, so we're
not exactly bound by their constraints.
--
Pedro
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