Hi Rob, Ard, On Wed, Jan 3, 2024 at 9:01 AM Rob Herring <r...@kernel.org> wrote: > > On Fri, Dec 22, 2023 at 5:48 AM Ard Biesheuvel <a...@kernel.org> wrote: > > > > On Thu, 21 Dec 2023 at 17:50, Chiu, Chasel <chasel.c...@intel.com> wrote: > > > > > > > > > Hi Ard, > > > > > > Please see my reply below inline and let me know your thoughts. > > > > > > Thanks, > > > Chasel > > > > > > > > > > -----Original Message----- > > > > From: Ard Biesheuvel <a...@kernel.org> > > > > Sent: Thursday, December 21, 2023 6:31 AM > > > > To: Chiu, Chasel <chasel.c...@intel.com> > > > > Cc: Simon Glass <s...@chromium.org>; devicet...@vger.kernel.org; Mark > > > > Rutland > > > > <mark.rutl...@arm.com>; Rob Herring <r...@kernel.org>; Tan, Lean Sheng > > > > <sheng....@9elements.com>; lkml <linux-ker...@vger.kernel.org>; Dhaval > > > > Sharma <dha...@rivosinc.com>; Brune, Maximilian > > > > <maximilian.br...@9elements.com>; Yunhui Cui <cuiyun...@bytedance.com>; > > > > Dong, Guo <guo.d...@intel.com>; Tom Rini <tr...@konsulko.com>; ron > > > > minnich > > > > <rminn...@gmail.com>; Guo, Gua <gua....@intel.com>; linux- > > > > a...@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 Tue, 28 Nov 2023 at 21:31, Chiu, Chasel <chasel.c...@intel.com> > > > > wrote: > > > > > > > > > > > > > > > > > > > > > > > > > > -----Original Message----- > > > > > > From: Ard Biesheuvel <a...@kernel.org> > > > > > > Sent: Tuesday, November 28, 2023 10:08 AM > > > > > > To: Chiu, Chasel <chasel.c...@intel.com> > > > > > > Cc: Simon Glass <s...@chromium.org>; devicet...@vger.kernel.org; > > > > > > Mark > > > > > > Rutland <mark.rutl...@arm.com>; Rob Herring <r...@kernel.org>; Tan, > > > > > > Lean Sheng <sheng....@9elements.com>; lkml > > > > > > <linux-ker...@vger.kernel.org>; Dhaval Sharma <dha...@rivosinc.com>; > > > > > > Brune, Maximilian <maximilian.br...@9elements.com>; Yunhui Cui > > > > > > <cuiyun...@bytedance.com>; Dong, Guo <guo.d...@intel.com>; Tom Rini > > > > > > <tr...@konsulko.com>; ron minnich <rminn...@gmail.com>; Guo, Gua > > > > > > <gua....@intel.com>; linux- a...@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.c...@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-memory-types-and-mapping-to-acpi-address-range-types > > > > > > > > > > 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. > > > > > > > > > > > > > The gEfiMemoryTypeInformationGuid HOB typically carries platform > > > > defaults, and > > > > the actual memory type information is kept in a non-volatile EFI > > > > variable, which > > > > gets updated when the memory usage changes. Is this different for > > > > UefiPayloadPkg? > > > > > > > > (For those among the cc'ees less versed in EFI/EDK2: when you get the > > > > 'config > > > > changed -rebooting' message from the boot firmware, it typically means > > > > that this > > > > memory type table has changed, and a reboot is necessary.) > > > > > > > > So the platform init needs to read this variable, or get the > > > > information in a > > > > different way. I assume it is the payload, not the platform init that > > > > updates the > > > > variable when necessary. This means the information flows from > > > > payload(n) to > > > > platform init(n+1), where n is a monotonic index tracking consecutive > > > > boots of the > > > > system. > > > > > > > > Can you explain how the DT fits into this? How are the runtime-code and > > > > runtime-data memory reservation nodes under /reserved-memory used to > > > > implement this information exchange between platform init and payload? > > > > And > > > > how do the HOB and the EFI variable fit into this picture? > > > > > > > > > 1. With some offline discussion, we would move > > > gEfiMemoryTypeInformationGuid usage to FDT->upl-custom node. This is > > > because it is edk2 implementation choice and non-edk2 PlatformInit or > > > Payload may not have such memory optimization implementation. (not a > > > generic usage/requirement for PlatformInit and Payload) > > > > > > The edk2 example flow will be like below: > > > > > > PlatformInit to GetVariable of gEfiMemoryTypeInformationGuid and create > > > Hob-> > > > PlatformInit to initialize FDT->upl-custom node to report > > > gEfiMemoryTypeInformationGuid HOB information -> > > > UefiPayload entry to re-create gEfiMemoryTypeInformationGuid HOB > > > basing on FDT input (instead of the default MemoryType inside > > > UefiPayload) -> > > > UefiPayload DxeMain/Gcd will consume gEfiMemoryTypeInformationGuid > > > Hob for memory type information -> > > > UefiPayload to initialize UEFI environment (mainly DXE > > > dispatcher) -> > > > (additional FV binary appended to common UefiPayload binary) > > > PlatformPayload to provide VariableService which is platform specific -> > > > UefiPayload UefiBootManager will SetVariable if memory type > > > change needed and request a warm reset -> > > > Back to PlatformInit ... > > > > > > > OK so the upl-custom node can do whatever it needs to. I imagine these > > will include the memory descriptor attribute field, and other parts > > that may be missing from the /reserved-memory DT node specification?
>From my side, ideally this will be empty, but it may be needed to make things work. > > > > > > > > 2. Now the proposed reserved-memory node usages will be for PlatformInit > > > to provide data which may be used by Payload or OS. This is not edk2 > > > specific and any PlatformInit/Payload could have same support. > > > Note: all of below are optional and PlatformInit may choose to implement > > > some of them or not. > > > > > > - acpi > > > If PlatformInit created some ACPI tables, this will report a memory > > > region which contains all the tables to Payload and Payload may base on > > > this to add some more tables if required. > > > > > > - acpi-nvs > > > If PlatformInit has created some ACPI tables which having ACPI NVS memory > > > dependency, this will be that nvs region. > > > > > > > These make sense. > > > > > - boot-code > > > When PlatformInit having some FW boot phase code that could be freed for > > > OS to use when payload transferring control to UEFI OS > > > > > > - boot-data > > > When PlatformInit having some FW boot phase data that could be freed for > > > OS to use when payload transferring control to UEFI OS. > > > > > > - runtime-code > > > PlatformInit may provide some services code that can be used for Payload > > > to initialize UEFI Runtime Services for supporting UEFI OS. > > > > > > - runtime-data > > > PlatformInit may provide some services data that can be used for Payload > > > to Initialize UEFI Runtime Services for supporting UEFI OS. > > > > > I'll say it again. "boot" and "runtime" on their own could mean about > anything, but the usage here is clearly tied to UEFI (or the EDK2 > implementation) and its meaning of boot and runtime. So the naming > needs to reflect that. > Chasel has made a suggestion. > > > A UEFI OS must consume this information from the UEFI memory map, not > > from the /reserved-memory nodes. So these nodes must either not be > > visible to the OS at all, or carry an annotation that the OS must > > ignore them. > > The kernel will process /reserved-memory for UEFI boot, so the > expectation is anything in the EFI memory map is not present there. An > annotation to ignore some nodes would require going back in time or > accepting 2 sources of truth on existing OS. The DT spec says: >>>>> 3.5.4 /reserved-memory and UEFI When booting via [UEFI], static /reserved-memory regions must also be listed in the system memory map obtained via the GetMemoryMap() UEFI boot time service as defined in [UEFI] § 7.2. The reserved memory regions need to be included in the UEFI memory map to protect against allocations by UEFI applications. <<<<< To my reading, that means that the requirement is that the /reserved-memory regions must be returned from the GetMemoryMap() call too. I don't see it saying that the reserved-memory regions must be empty, though. > > > Would it be possible to include a restriction in the DT schema that > > these are only valid in the firmware boot phase? > > The only way ATM is including a schema or not when running validation > on a DT for a particular boot phase. Include the schema in the project > that wants to use these nodes and don't include it in cases that don't > use it. I don't see a reason why this needs to be in dtschema. We would like to use a single schema, which is dtschema. UPL validation will eventually check this, so it needs to be correct. Regards, Simon
