On Mon, Mar 20, 2017 at 10:01:09AM +0100, Laszlo Ersek wrote:
> >> Because this protocol is not standard, it is prefixed with EDKII / Edkii,
> >> as seen elsewhere in MdeModulePkg and SecurityPkg, for example. (ARM / Arm
> >> doesn't look future-proof enough; future UEFI platforms could face the
> >> same issue.) In addition, an effort is made to avoid the phrase
> >> "AcpiPlatform", as that belongs to drivers / libraries that produce
> >> platform specific ACPI content (as opposed to deciding whether the entire
> >> firmware will have access to EFI_ACPI_TABLE_PROTOCOL).
> >
> > I greatly approve, but since you've already done this generically - is
> > there any good reason to keep this in ArmPkg?
> > I am strongly looking to get rid of "things that happen to have been
> > implemented for ARM" from there and pruning it down to contain only
> > things that are architecturelly ARM-specific.
>
> This patch is not specific to ARM architecturally, but it is specific to
> the ARM ecosystem / community. I'm unaware of another platform (that
> would affect edk2 ATM anyway) where such a conflict in beliefs has not
> been sorted out for years.
Indeed. However, I have developed a mild allergy towards things that
are not fundamentally ARM-specific, but are treated as such.
It tends to introduce a mental barrier towards code unification and
sharing, since it makes it look like an architecture-specific component.
> The somewhat speculative generality in the naming (i.e., Edkii prefix
> rather than Arm) is there only because I understand that DT / libfdt is
> used on other platforms as well, and I expect once those see UEFI (and
> edk2) enablement & porting, the same DT vs. ACPI conflict in Linux space
> will extend to those platforms as well.
>
> IOW, at the moment the patch is specific to ARM, it is not random, but
> it could change in the future. And, I wouldn't like to force client
> modules to rename the GUID at that time.
Oh, I perfectly agree.
I'm just saying I don't think that a feature only being applicable to
ARM at the current moment should be a barrier for it being introduced
in Mde*Pkg.
> > MdeModulePkg?
>
> Not a bad idea, but the point of this approach was to avoid touching
> core modules. If we modify MdeModulePkg *logic* (as opposed to the
> trivial typo fix elsewhere in this series), then the simplest solution
> is to just add a dynamic PCD to MdeModulePkg.dec, which forces
> AcpiTableDxe to exit immediately with EFI_ABORTED or EFI_UNSUPPORTED.
That actually sounds more palatable to me than this set, which I still
prefer over Ard's solution (I'll expand on my reservations about that
one on the correct thread).
> As I mentioned earlier, PcdAcpiS3Enable had been introduced very
> similarly to this. It controls partial or full functionality of several
> DXE drivers:
>
> 11a291a4d279 MdeModulePkg: Introduce new PCD PcdAcpiS3Enable
> a1726e308903 OvmfPkg: Set PcdAcpiS3Enable according to
> QemuFwCfgS3Enabled()
> 125e09387641 MdeModulePkg S3SaveStateDxe: Consume PcdAcpiS3Enable to
> control the code
> e96708de8837 IntelFrameworkModulePkg AcpiS3SaveDxe: Consume
> PcdAcpiS3Enable to control the code
> d2d38610603f MdeModulePkg SmmS3SaveStateDxe: Consume PcdAcpiS3Enable
> to control the code
> 800c02fbe2da MdeModulePkg BootScriptExecutorDxe: Consume
> PcdAcpiS3Enable to control the code
> ca98f6038294 UefiCpuPkg/CpuS3DataDxe: Consume PcdAcpiS3Enable to
> control the code
> b10d5ddc0385 UefiCpuPkg/PiSmmCpuDxeSmm: Consume PcdAcpiS3Enable to
> control the code
>
> If the AcpiTableDxe maintainers aren't opposed to another dynamic PCD
> like PcdAcpiS3Enable -- but in this case for controlling AcpiTableDxe --
> then I'm fine with it too.
>
> ... I knew that new PCDs in MdeModulePkg needed strong justification, so
> I figured I'd try another route first.
Yes, I understand. But I think it is well motivated here, and the
solution that feels the most UEFI to me.
Regards,
Leif
> Thanks
> Laszlo
>
> >
> > Regards,
> >
> > Leif
> >
> >> Cc: Ard Biesheuvel <ard.biesheu...@linaro.org>
> >> Cc: Leif Lindholm <leif.lindh...@linaro.org>
> >> Contributed-under: TianoCore Contribution Agreement 1.0
> >> Signed-off-by: Laszlo Ersek <ler...@redhat.com>
> >> ---
> >> ArmPkg/ArmPkg.dec | 4 ++
> >> ArmPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.inf | 40
> >> ++++++++++++++++++++
> >> ArmPkg/Include/Protocol/PlatformHasAcpi.h | 34
> >> +++++++++++++++++
> >> ArmPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.c | 36
> >> ++++++++++++++++++
> >> 4 files changed, 114 insertions(+)
> >>
> >> diff --git a/ArmPkg/ArmPkg.dec b/ArmPkg/ArmPkg.dec
> >> index c4b4da2f95bb..0e49360a386a 100644
> >> --- a/ArmPkg/ArmPkg.dec
> >> +++ b/ArmPkg/ArmPkg.dec
> >> @@ -52,6 +52,10 @@ [Ppis]
> >> ## Include/Ppi/ArmMpCoreInfo.h
> >> gArmMpCoreInfoPpiGuid = { 0x6847cc74, 0xe9ec, 0x4f8f, {0xa2, 0x9d,
> >> 0xab, 0x44, 0xe7, 0x54, 0xa8, 0xfc} }
> >>
> >> +[Protocols]
> >> + ## Include/Protocol/PlatformHasAcpi.h
> >> + gEdkiiPlatformHasAcpiProtocolGuid = { 0xf0966b41, 0xc23f, 0x41b9,
> >> { 0x96, 0x04, 0x0f, 0xf7, 0xe1, 0x11, 0x96, 0x5a } }
> >> +
> >> [PcdsFeatureFlag.common]
> >> gArmTokenSpaceGuid.PcdCpuDxeProduceDebugSupport|FALSE|BOOLEAN|0x00000001
> >>
> >> diff --git a/ArmPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.inf
> >> b/ArmPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.inf
> >> new file mode 100644
> >> index 000000000000..c83da4d8e98a
> >> --- /dev/null
> >> +++ b/ArmPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.inf
> >> @@ -0,0 +1,40 @@
> >> +## @file
> >> +# A hook-in library for MdeModulePkg/Universal/Acpi/AcpiTableDxe.
> >> +#
> >> +# Plugging this library instance into AcpiTableDxe makes
> >> +# EFI_ACPI_TABLE_PROTOCOL and (if enabled) EFI_ACPI_SDT_PROTOCOL depend
> >> on the
> >> +# platform's dynamic decision whether to expose an ACPI-based hardware
> >> +# description to the operating system.
> >> +#
> >> +# Universal and platform specific DXE drivers that produce ACPI tables
> >> depend
> >> +# on EFI_ACPI_TABLE_PROTOCOL / EFI_ACPI_SDT_PROTOCOL in turn.
> >> +#
> >> +# Copyright (C) 2017, Red Hat, Inc.
> >> +#
> >> +# This program and the accompanying materials are licensed and made
> >> available
> >> +# under the terms and conditions of the BSD License which accompanies this
> >> +# distribution. The full text of the license may be found at
> >> +# http://opensource.org/licenses/bsd-license.php
> >> +#
> >> +# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> >> WITHOUT
> >> +# WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> >> +##
> >> +
> >> +[Defines]
> >> + INF_VERSION = 1.25
> >> + BASE_NAME = PlatformHasAcpiLib
> >> + FILE_GUID = 29beb028-0958-447b-be0a-12229235d77d
> >> + MODULE_TYPE = BASE
> >> + VERSION_STRING = 1.0
> >> + LIBRARY_CLASS = PlatformHasAcpiLib|DXE_DRIVER
> >> + CONSTRUCTOR = PlatformHasAcpiInitialize
> >> +
> >> +[Sources]
> >> + PlatformHasAcpiLib.c
> >> +
> >> +[Packages]
> >> + ArmPkg/ArmPkg.dec
> >> + MdePkg/MdePkg.dec
> >> +
> >> +[Depex]
> >> + gEdkiiPlatformHasAcpiProtocolGuid
> >> diff --git a/ArmPkg/Include/Protocol/PlatformHasAcpi.h
> >> b/ArmPkg/Include/Protocol/PlatformHasAcpi.h
> >> new file mode 100644
> >> index 000000000000..3cd0cfe4515d
> >> --- /dev/null
> >> +++ b/ArmPkg/Include/Protocol/PlatformHasAcpi.h
> >> @@ -0,0 +1,34 @@
> >> +/** @file
> >> + EDKII Platform Has ACPI Protocol
> >> +
> >> + The presence of this protocol in the DXE protocol database implies that
> >> the
> >> + platform provides the operating system with an ACPI-based hardware
> >> + description. Note that this is not necessarily mutually exclusive with a
> >> + Device Tree-based hardware description. A platform driver is supposed to
> >> + produce a single instance of the protocol (with NULL contents), if
> >> + appropriate.
> >> +
> >> + Copyright (C) 2017, Red Hat, Inc.
> >> +
> >> + This program and the accompanying materials are licensed and made
> >> available
> >> + under the terms and conditions of the BSD License that accompanies this
> >> + distribution. The full text of the license may be found at
> >> + http://opensource.org/licenses/bsd-license.php.
> >> +
> >> + THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> >> WITHOUT
> >> + WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> >> +**/
> >> +
> >> +
> >> +#ifndef __EDKII_PLATFORM_HAS_ACPI_PROTOCOL_H__
> >> +#define __EDKII_PLATFORM_HAS_ACPI_PROTOCOL_H__
> >> +
> >> +#define EDKII_PLATFORM_HAS_ACPI_PROTOCOL_GUID \
> >> + { \
> >> + 0xf0966b41, 0xc23f, 0x41b9, \
> >> + { 0x96, 0x04, 0x0f, 0xf7, 0xe1, 0x11, 0x96, 0x5a } \
> >> + }
> >> +
> >> +extern EFI_GUID gEdkiiPlatformHasAcpiProtocolGuid;
> >> +
> >> +#endif
> >> diff --git a/ArmPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.c
> >> b/ArmPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.c
> >> new file mode 100644
> >> index 000000000000..79072da21c2b
> >> --- /dev/null
> >> +++ b/ArmPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.c
> >> @@ -0,0 +1,36 @@
> >> +/** @file
> >> + A hook-in library for MdeModulePkg/Universal/Acpi/AcpiTableDxe.
> >> +
> >> + Plugging this library instance into AcpiTableDxe makes
> >> + EFI_ACPI_TABLE_PROTOCOL and (if enabled) EFI_ACPI_SDT_PROTOCOL depend
> >> on the
> >> + platform's dynamic decision whether to expose an ACPI-based hardware
> >> + description to the operating system.
> >> +
> >> + Universal and platform specific DXE drivers that produce ACPI tables
> >> depend
> >> + on EFI_ACPI_TABLE_PROTOCOL / EFI_ACPI_SDT_PROTOCOL in turn.
> >> +
> >> + Copyright (C) 2017, Red Hat, Inc.
> >> +
> >> + This program and the accompanying materials are licensed and made
> >> available
> >> + under the terms and conditions of the BSD License which accompanies this
> >> + distribution. The full text of the license may be found at
> >> + http://opensource.org/licenses/bsd-license.php
> >> +
> >> + THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> >> WITHOUT
> >> + WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> >> +**/
> >> +
> >> +#include <Base.h>
> >> +
> >> +RETURN_STATUS
> >> +EFIAPI
> >> +PlatformHasAcpiInitialize (
> >> + VOID
> >> + )
> >> +{
> >> + //
> >> + // Do nothing, just imbue AcpiTableDxe with an
> >> + // EDKII_PLATFORM_HAS_ACPI_PROTOCOL dependency.
> >> + //
> >> + return RETURN_SUCCESS;
> >> +}
> >> --
> >> 2.9.3
> >>
> >>
>
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