-----Original Message----- From: Ard Biesheuvel ardb@kernel.org Sent: Tuesday, November 28, 2023 10:08 AM To: Chiu, Chasel chasel.chiu@intel.com Cc: Simon Glass sjg@chromium.org; devicetree@vger.kernel.org; Mark Rutland mark.rutland@arm.com; Rob Herring robh@kernel.org; Tan, Lean Sheng sheng.tan@9elements.com; lkml linux-kernel@vger.kernel.org; Dhaval Sharma dhaval@rivosinc.com; Brune, Maximilian maximilian.brune@9elements.com; Yunhui Cui cuiyunhui@bytedance.com; Dong, Guo guo.dong@intel.com; Tom Rini trini@konsulko.com; ron minnich rminnich@gmail.com; Guo, Gua gua.guo@intel.com; linux- acpi@vger.kernel.org; U-Boot Mailing List u-boot@lists.denx.de Subject: Re: [PATCH v7 2/2] schemas: Add some common reserved-memory usages
You are referring to a 2000 line patch so it is not 100% clear where to look tbh.
On Tue, 21 Nov 2023 at 19:37, Chiu, Chasel chasel.chiu@intel.com wrote:
In PR, UefiPayloadPkg/Library/FdtParserLib/FdtParserLib.c, line 268 is for
related example code.
That refers to a 'memory-allocation' node, right? How does that relate to the 'reserved-memory' node?
And crucially, how does this clarify in which way "runtime-code" and "runtime- data" reservations are being used?
Since the very beginning of this discussion, I have been asking repeatedly for examples that describe the wider context in which these reservations are used. The "runtime" into runtime-code and runtime-data means that these regions have a special significance to the operating system, not just to the next bootloader stage. So I want to understand exactly why it is necessary to describe these regions in a way where the operating system might be expected to interpret this information and act upon it.
I think runtime code and data today are mainly for supporting UEFI runtime services - some BIOS functions for OS to utilize, OS may follow below ACPI spec to treat them as reserved range: https://uefi.org/specs/ACPI/6.5/15_System_Address_Map_Interfaces.html#uefi-m...
Like I mentioned earlier, that PR is still in early phase and has not reflected all the required changes yet, but the idea is to build gEfiMemoryTypeInformationGuid HOB from FDT reserved-memory nodes. UEFI generic Payload has DxeMain integrated, however Memory Types are platform-specific, for example, some platforms may need bigger runtime memory for their implementation, that's why we want such FDT reserved-memory node to tell DxeMain.
The Payload flow will be like this: Payload creates built-in default MemoryTypes table -> FDT reserved-memory node to override if required (this also ensures the same memory map cross boots so ACPI S4 works) -> Build gEfiMemoryTypeInformationGuid HOB by "platfom specific" MemoryTypes Table -> DxeMain/GCD to consume this MemoryTypes table and setup memory service -> Install memory types table to UEFI system table.Configuration table...
Note: if Payload built-in default MemoryTypes table works fine for the platform, then FDT reserved-memory node does not need to provide such 'usage' compatible strings. (optional) This FDT node could allow flexibility/compatibility without rebuilding Payload binary.
Not sure if I answered all your questions, please highlight which area you need more information.
Thanks, Chasel
-----Original Message----- From: Chiu, Chasel Sent: Tuesday, November 21, 2023 10:34 AM To: Ard Biesheuvel ardb@kernel.org; Simon Glass sjg@chromium.org Cc: devicetree@vger.kernel.org; Mark Rutland mark.rutland@arm.com; Rob Herring robh@kernel.org; Tan, Lean Sheng sheng.tan@9elements.com; lkml linux-kernel@vger.kernel.org; Dhaval Sharma dhaval@rivosinc.com; Brune, Maximilian maximilian.brune@9elements.com; Yunhui Cui cuiyunhui@bytedance.com; Dong, Guo guo.dong@intel.com; Tom Rini trini@konsulko.com; ron minnich rminnich@gmail.com; Guo, Gua gua.guo@intel.com; linux-acpi@vger.kernel.org; U-Boot Mailing List <u- boot@lists.denx.de>; Chiu, Chasel chasel.chiu@intel.com Subject: RE: [PATCH v7 2/2] schemas: Add some common reserved-memory usages
Hi Ard,
Here is the POC PR for your reference: https://github.com/tianocore/edk2/pull/4969/files#diff-
ccebabae5274b21634723a2111ee0de11bed6cfe8cb206ef9e263d9c5f926a9cR26
8 Please note that this PR is still in early phase and expected to have significant changes.
The idea is that payload entry will create gEfiMemoryTypeInformationGuid HOB with payload default memory types and allow FDT to override if correspond node present. Please let me know if you have questions or suggestions.
Thanks, Chasel
-----Original Message----- From: Ard Biesheuvel ardb@kernel.org Sent: Tuesday, November 21, 2023 8:42 AM To: Simon Glass sjg@chromium.org Cc: Chiu, Chasel chasel.chiu@intel.com; devicetree@vger.kernel.org; Mark Rutland mark.rutland@arm.com; Rob Herring robh@kernel.org; Tan, Lean Sheng sheng.tan@9elements.com; lkml linux-kernel@vger.kernel.org; Dhaval Sharma dhaval@rivosinc.com; Brune, Maximilian maximilian.brune@9elements.com; Yunhui Cui cuiyunhui@bytedance.com; Dong, Guo guo.dong@intel.com; Tom Rini trini@konsulko.com; ron minnich rminnich@gmail.com; Guo, Gua gua.guo@intel.com; linux- acpi@vger.kernel.org; U-Boot Mailing List u-boot@lists.denx.de Subject: Re: [PATCH v7 2/2] schemas: Add some common reserved-memory usages
On Mon, 20 Nov 2023 at 21:12, Simon Glass sjg@chromium.org wrote:
Hi,
On Mon, 13 Nov 2023 at 11:09, Chiu, Chasel chasel.chiu@intel.com
wrote:
Hi Ard,
Please see my reply below inline.
Thanks, Chasel
> -----Original Message----- > From: Ard Biesheuvel ardb@kernel.org > Sent: Saturday, November 11, 2023 3:04 AM > To: Chiu, Chasel chasel.chiu@intel.com > Cc: Simon Glass sjg@chromium.org; > devicetree@vger.kernel.org; Mark Rutland > mark.rutland@arm.com; Rob Herring robh@kernel.org; Tan, > Lean Sheng sheng.tan@9elements.com; lkml > linux-kernel@vger.kernel.org; Dhaval Sharma > dhaval@rivosinc.com; Brune, Maximilian > maximilian.brune@9elements.com; Yunhui Cui > cuiyunhui@bytedance.com; Dong, Guo guo.dong@intel.com; > Tom Rini trini@konsulko.com; ron minnich > rminnich@gmail.com; Guo, Gua gua.guo@intel.com; linux- > acpi@vger.kernel.org; U-Boot Mailing List > u-boot@lists.denx.de > Subject: Re: [PATCH v7 2/2] schemas: Add some common > reserved-memory usages > > On Sat, 11 Nov 2023 at 04:20, Chiu, Chasel > chasel.chiu@intel.com
wrote:
> > > > > > Just sharing some usage examples from UEFI/EDK2 scenario. > > To support ACPI S4/Hibernation, memory map must be > > consistent before entering and after resuming from S4, in > > this case payload may need to know previous memory map > > from bootloader (currently generic payload cannot access > > platform/bootloader specific non-volatile data, thus could > > not save/restore memory map > > information) > > So how would EDK2 reconstruct the entire EFI memory map from > just these unannotated /reserved-memory nodes? The EFI > memory map contains much more information than that, and all > of it has to match the pre-hibernate situation, right? Can you given an
example?
Here we listed only typically memory types that may change cross different
platforms.
Reserved memory type already can be handled by reserved-memory node,
and rest of the types usually no need to change cross platforms thus currently we could rely on default in generic payload.
In the future if we see a need to add new memory types we will discuss and
add it to FDT schema.
> > > Another usage is to support binary model which generic > > payload is a prebuilt > binary compatible for all platforms/configurations, however > the payload default memory map might not always work for all > the configurations and we want to allow bootloader to > override payload default
memory map without recompiling.
> > > > Agreed. But can you explain how a EDK2 payload might make > meaningful use of 'runtime-code' regions provided via DT by > the > non-EDK2 platform init? Can you give an example?
Runtime-code/data is used by UEFI payload for booting UEFI OS which
required UEFI runtime services.
Platform Init will select some regions from the usable memory and assign it to
runtime-code/data for UPL to consume. Or assign same runtime-code/data from previous boot.
If UEFI OS is not supported, PlatformInit may not need to provide runtime-code/data regions to payload. (always providing runtime-code/data should be supported too)
> > > Under below assumption: > > FDT OS impact has been evaluated and taken care by > > relevant > experts/stakeholders. > > Reviewed-by: Chasel Chiu chasel.chiu@intel.com > > > > I am sorry but I don't know what 'FDT OS impact' means. We > are talking about a firmware-to-firmware abstraction that > has the potential to leak into the OS visible interface. > > I am a maintainer in the Tianocore project myself, so it > would help if you could explain who these relevant experts > and stakeholders are. Was this discussed on the edk2-devel > mailing list? If so, apologies for missing it but I may not have been cc'ed
perhaps?
I'm not familiar with FDT OS, also I do not know if who from edk2-devel were
supporting FDT OS, I think Simon might be able to connect FDT OS experts/stakeholders.
We are mostly focusing on payload firmware phase implementation in edk2 (and other payloads too), however, since we have aligned the payload FDT and OS FDT months ago, I'm assuming FDT OS impact must be there and we need (or already done?) FDT OS experts to support it. (again, maybe Simon could share more information about FDT OS)
In edk2 such FDT schema is UefiPayloadPkg internal usage only and payload
entry will convert FDT into HOB thus we expected the most of the edk2 generic code are no-touch/no impact, that's why we only had small group (UefiPayloadPkg) discussion.
Ard, if you are aware of any edk2 code that's for supporting FDT OS, please let
us know and we can discuss if those code were impacted or not.
We discussed this and just to clarify, 'FDT OS' is not a special OS, it is just Linux.
So, with the above, are we all on the same page? Can the patch be applied, perhaps? If not, what other discussion is needed?
An example of how a platform-init/payload combination would make meaningful use of such runtime-code/data regions.