Hi Rob, On Mon, 16 Oct 2023 at 15:54, Simon Glass <sjg@xxxxxxxxxxxx> wrote: > > Hi Rob, > > On Mon, 16 Oct 2023 at 10:50, Rob Herring <robh@xxxxxxxxxx> wrote: > > > > On Fri, Oct 13, 2023 at 4:09 PM Simon Glass <sjg@xxxxxxxxxxxx> wrote: > > > > > > Hi Rob, > > > > > > On Fri, 13 Oct 2023 at 13:42, Rob Herring <robh@xxxxxxxxxx> wrote: > > > > > > > > On Fri, Oct 6, 2023 at 7:03 PM Simon Glass <sjg@xxxxxxxxxxxx> wrote: > > > > > > > > > > Hi Ard, > > > > > > > > > > On Fri, 6 Oct 2023 at 17:00, Ard Biesheuvel <ardb@xxxxxxxxxx> wrote: > > > > > > > > > > > > On Fri, 6 Oct 2023 at 20:17, Simon Glass <sjg@xxxxxxxxxxxx> wrote: > > > > > > > > > > > > > > Hi Ard, > > > > > > > > > > > > > > On Fri, 6 Oct 2023 at 11:33, Ard Biesheuvel <ardb@xxxxxxxxxx> wrote: > > > > > > > > > > > > > > > > On Mon, 2 Oct 2023 at 19:54, Simon Glass <sjg@xxxxxxxxxxxx> wrote: > > > > > > > > > > > > > > > > > > Hi Rob, > > > > > > > > > > > > > > > > > > On Tue, 26 Sept 2023 at 13:42, Simon Glass <sjg@xxxxxxxxxxxx> wrote: > > > > > > > > > > > > > > > > > > > > It is common to split firmware into 'Platform Init', which does the > > > > > > > > > > initial hardware setup and a "Payload" which selects the OS to be booted. > > > > > > > > > > Thus an handover interface is required between these two pieces. > > > > > > > > > > > > > > > > > > > > Where UEFI boot-time services are not available, but UEFI firmware is > > > > > > > > > > present on either side of this interface, information about memory usage > > > > > > > > > > and attributes must be presented to the "Payload" in some form. > > > > > > > > > > > > > > > > > > > > This aims to provide an small schema addition for the memory mapping > > > > > > > > > > needed to keep these two pieces working together well. > > > > > > > > > > > > > > > > > > > > Signed-off-by: Simon Glass <sjg@xxxxxxxxxxxx> > > > > > > > > > > --- > > > > > > > > > > > > > > > > > > > > Changes in v7: > > > > > > > > > > - Rename acpi-reclaim to acpi > > > > > > > > > > - Drop individual mention of when memory can be reclaimed > > > > > > > > > > - Rewrite the item descriptions > > > > > > > > > > - Add back the UEFI text (with trepidation) > > > > > > > > > > > > > > > > > > I am again checking on this series. Can it be applied, please? > > > > > > > > > > > > > > > > > > > > > > > > > Apologies for the delay in response. I have been away. > > > > > > > > > > > > > > OK, I hope you had a nice trip. > > > > > > > > > > > > > > > > > > > Thanks, it was wonderful! > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Changes in v6: > > > > > > > > > > - Drop mention of UEFI > > > > > > > > > > - Use compatible strings instead of node names > > > > > > > > > > > > > > > > > > > > Changes in v5: > > > > > > > > > > - Drop the memory-map node (should have done that in v4) > > > > > > > > > > - Tidy up schema a bit > > > > > > > > > > > > > > > > > > > > Changes in v4: > > > > > > > > > > - Make use of the reserved-memory node instead of creating a new one > > > > > > > > > > > > > > > > > > > > Changes in v3: > > > > > > > > > > - Reword commit message again > > > > > > > > > > - cc a lot more people, from the FFI patch > > > > > > > > > > - Split out the attributes into the /memory nodes > > > > > > > > > > > > > > > > > > > > Changes in v2: > > > > > > > > > > - Reword commit message > > > > > > > > > > > > > > > > > > > > .../reserved-memory/common-reserved.yaml | 71 +++++++++++++++++++ > > > > > > > > > > 1 file changed, 71 insertions(+) > > > > > > > > > > create mode 100644 dtschema/schemas/reserved-memory/common-reserved.yaml > > > > > > > > > > > > > > > > > > > > diff --git a/dtschema/schemas/reserved-memory/common-reserved.yaml b/dtschema/schemas/reserved-memory/common-reserved.yaml > > > > > > > > > > new file mode 100644 > > > > > > > > > > index 0000000..f7fbdfd > > > > > > > > > > --- /dev/null > > > > > > > > > > +++ b/dtschema/schemas/reserved-memory/common-reserved.yaml > > > > > > > > > > @@ -0,0 +1,71 @@ > > > > > > > > > > +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause > > > > > > > > > > +%YAML 1.2 > > > > > > > > > > +--- > > > > > > > > > > +$id: http://devicetree.org/schemas/reserved-memory/common-reserved.yaml# > > > > > > > > > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > > > > > > > > > + > > > > > > > > > > +title: Common memory reservations > > > > > > > > > > + > > > > > > > > > > +description: | > > > > > > > > > > + Specifies that the reserved memory region can be used for the purpose > > > > > > > > > > + indicated by its compatible string. > > > > > > > > > > + > > > > > > > > > > + Clients may reuse this reserved memory if they understand what it is for, > > > > > > > > > > + subject to the notes below. > > > > > > > > > > + > > > > > > > > > > +maintainers: > > > > > > > > > > + - Simon Glass <sjg@xxxxxxxxxxxx> > > > > > > > > > > + > > > > > > > > > > +allOf: > > > > > > > > > > + - $ref: reserved-memory.yaml > > > > > > > > > > + > > > > > > > > > > +properties: > > > > > > > > > > + compatible: > > > > > > > > > > + description: | > > > > > > > > > > + This describes some common memory reservations, with the compatible > > > > > > > > > > + string indicating what it is used for: > > > > > > > > > > + > > > > > > > > > > + acpi: Advanced Configuration and Power Interface (ACPI) tables > > > > > > > > > > + acpi-nvs: ACPI Non-Volatile-Sleeping Memory (NVS). This is reserved by > > > > > > > > > > + the firmware for its use and is required to be saved and restored > > > > > > > > > > + across an NVS sleep > > > > > > > > > > + boot-code: Contains code used for booting which is not needed by the OS > > > > > > > > > > + boot-code: Contains data used for booting which is not needed by the OS > > > > > > > > > > + runtime-code: Contains code used for interacting with the system when > > > > > > > > > > + running the OS > > > > > > > > > > + runtime-data: Contains data used for interacting with the system when > > > > > > > > > > + running the OS > > > > > > > > > > + > > > > > > > > > > + enum: > > > > > > > > > > + - acpi > > > > > > > > > > + - acpi-nvs > > > > > > > > > > + - boot-code > > > > > > > > > > + - boot-data > > > > > > > > > > + - runtime-code > > > > > > > > > > + - runtime-data > > > > > > > > > > + > > > > > > > > > > > > > > > > As I mentioned a few times already, I don't think these compatibles > > > > > > > > should be introduced here. > > > > > > > > > > > > > > > > A reserved region has a specific purpose, and the compatible should be > > > > > > > > more descriptive than the enum above. If the consumer does not > > > > > > > > understand this purpose, it should simply treat the memory as reserved > > > > > > > > and not touch it. Alternatively, these regions can be referenced from > > > > > > > > other DT nodes using phandles if needed. > > > > > > > > > > > > > > We still need some description of what these regions are used for, so > > > > > > > that the payload can use the correct regions. I do not have any other > > > > > > > solution to this problem. We are in v7 at present. At least explain > > > > > > > where you want the compatible strings to be introduced. > > > > > > > > > > > > > > > > > > > My point is really that by themselves, these regions are not usable by > > > > > > either a payload or an OS that consumes this information. Unless there > > > > > > is some other information being provided (via DT I imagine) that > > > > > > describes how these things are supposed to be used, they are nothing > > > > > > more than memory reservations that should be honored, and providing > > > > > > this arbitrary set of labels is unnecessary. > > > > > > > > > > > > > What sort of extra detail are you looking for? Please be specific and > > > > > > > preferably add some suggestions so I can close this out ASAP. > > > > > > > > > > > > > > > > > > > A payload or OS can do nothing with a memory reservation called > > > > > > 'runtime-code' it it doesn't know what is inside. > > > > > > > > Agreed. The question is WHAT runtime-code? The compatible needs to answer that. > > > > > > > > For example, we have 'ramoops' as a compatible in reserved memory. > > > > That tells us *exactly* what's there. We know how to parse it. If we > > > > know ramoops is not supported, then we know we can toss it out and > > > > reclaim the memory. > > > > > > So if we said: > > > > > > compatible = "runtime-code-efi" > > > > > > would that be OK? We seem to be in catch 22 here, because if I don't > > > mention EFI unhappy, but if I do, Ard is unhappy. > > > > Better yes, because then it is for something specific. However, AIUI, > > that's setup for the OS and defining that region is already defined by > > the EFI memory map. That's Ard's issue. If there's a need outside of > > the EFI to OS handoff, > > There is a need. Here is part of the commit message again. If there is > something else you need to know, please ask. > > >>>> > It is common to split firmware into 'Platform Init', which does the > initial hardware setup and a "Payload" which selects the OS to be booted. > Thus an handover interface is required between these two pieces. > > Where UEFI boot-time services are not available, but UEFI firmware is > present on either side of this interface, information about memory usage > and attributes must be presented to the "Payload" in some form. > <<< > > > then you need to define what that usecase looks > > like. Describe the problem rather than present your solution. > > > > If this is all specific to EDK2 then it should say that rather than > > 'efi'. I imagine Ard would be happier with something tied to EDK2 than > > *all* UEFI. Though maybe the problem could be any implementation? IDK. > > Maybe it's TF-A that needs to define where the EFI runtime services > > region is and that needs to be passed all the way thru to the EFI > > implementation? So again, define the problem. > > It is not specific to EDK2. Imagine this boot sequence: > > - Platform Init (U-Boot) starts up > - U-Boot uses its platform knowledge to sets some ACPI tables and put > various things in memory > - U-Boot sets up some runtime code and data for the OS > - U-Boot jumps to the Tianocore payload ** > - Payload (Tianocore) wants to know where the ACPI tables are, for example > - Tianocore needs to provide boot services to the OS, so needs to know > the memory map, etc. > > ** At this point we want to use DT to pass the required information. > > Of course, Platform Init could be coreboot or Tianocore or some > strange private binary. Payload could be U-Boot or something else. > That is the point of this effort, to build interoperability. > > > > > > What about the boottime code....you want to know which project it is from? > > > > I think it is the same. > > > > > > > > + - acpi > > > + - acpi-nvs > > > > > > Those two should be enough info, right? > > > > I think so. NVS is not a term I've heard in relation to ACPI, but that > > may just be my limited ACPI knowledge. > > Perhaps it is only an Intel thing. It stands for Non-Volatile-Sleeping > Memory and it has various platform settings in a binary format that is > normally SoC-specific. > > > > > > + - boot-code > > > + - boot-data > > > > > > For these, they don't pertain to the OS, so perhaps they are OK? > > > > Hard to tell that just from the name... 'boot' could be any component > > involved in booting including the OS. > > suggested that 'boot' should mean booting the OS. If the OS does lots > of fixup stuff at the start of it, I don't know what that is called. > > So if boot-code is no good, what do you suggest? > > Alternatively I could remove these for now, if it will help make progress. > > > > > > In > > > any case, using a generic term like this makes some sense to me. We > > > can always add a new compatible like "efi-boottime-services" later. It > > > may be that the boottime services would be handled by the payload, so > > > not needed in all cases. > > > > Why later? You have a specific use in mind and I imagine Ard has > > thoughts on that. > > Because we don't need it right away, and just want to make some progress. > > Perhaps the problem here is that Linux has tied itself up in knots > with its EFI stuff and DT fixups and what-not. But this is not that. > It is a simple handoff between two pieces of firmware, Platform Init > and Payload. It has nothing to do with the OS. With Tianocore they are > typically combined, but with this usage they are split, and we can > swap out one project for another on either side of the DT interface. > > I do have views on the 'EFI' opt-out with reserved-memory, if you are > interested, but that relates to the OS. If you are wanting to place > some constraints on /reserved-memory and /memory we could do that > e.g. that the DT and the map returned by EFI boot services must be > consistent. But as it is, the nodes are ignored by the OS when booting > with EFI, aren't they? Can this be applied, please? If there are further comments, please let me know. Regards, Simon
