Hi Simon,
On Thu, 7 Sept 2023 at 15:23, Simon Glass sjg@chromium.org wrote:
Hi Ilias,
On Wed, 6 Sept 2023 at 23:20, Ilias Apalodimas ilias.apalodimas@linaro.org wrote:
Hi Rob,
[...]
> > > > What is the point of removing them? Instead, we should make sure that > > we upstream the bindings and encourage SoC vendors to sync them. If we > > remove them, no one will bother and U-Boot just becomes a dumping > > ground. > > Well things like the binman entries in DT are U-Boot specific and not > useful for HW related descriptions or for Linux or another OS being > able to deal with HW so arguably we're already a dumping ground to > some degree for not defining hardware.
I have started the process to upstream the binman bindings.
I don't think they should be in DT at all, they don't describe anything to do with hardware, or generally even the runtime of a device, they don't even describe the boot/runtime state of the firmware, they describe build time, so I don't see what that has to do with device tree? Can you explain that? To me those sorts of things should live in a build time style config file.
For the record, I tend to agree.
+1
I beg to differ. Devicetree is more than just hardware and always has been. See, for example the /chosen and /options nodes.
There are exceptions...
We've been this over and over again and frankly it gets a bit annoying. It's called *DEVICE* tree for a reason. As Rob pointed out there are exceptions, but those made a lot of sense. Having arbitrary internal ABI stuff of various projects in the schema just defeats the definition of a spec.
Our efforts should not just be about internal ABI, but working to provide a consistent configuration system for all firmware elements.
And that's what the firmware handoff was all about. I get what you are trying to do here. I am just aware of any other project apart from U-Boot which uses DT for it's own configuration. So trying to standardize some bindings that are useful to all projects that use DT is fine. Trying to *enforce* them to use it for config isn't IMHO.
We cannot have it both ways, i.e. refusing to accept non-hardware bindings and then complaining that U-Boot does not pass schema validation. Devicetree should be a shared resource, not just for the use of Linux.
It's not for the use of Linux, I've wasted enough time repeating that and so has Rob. Please go back to previous emails and read the arguments.
We already have reserved-memory, flash layout and other things which don't relate to hardware. I would love to somehome get past this fundamental discussion which seems to come up every time we get close to making progress
Most of the nodes we already have were used across projects and made sense to all of them. U-Boot might need to reserve some memory and so does linux etc etc. Some other nodes make nosense at all to and they just serve internal ABI implementation details. I can't possibly fathom how these would be justifiable. On top of all that, there's a huge danger here. How are you planning on separating arbitrary entries from various projects?
What I am afraid is going to happen here is simple. If a project doesn't use DT to configure itself and wants to provide a DT to U-Boot, then are you going to say "Can you please inject various DT nodes in the tree because U-Boot *needs* them and they are now part of the spec"? Anyway, it's not up to me to decide here, I am just saying what makes sense to me.
We need run-time configuration here, since we cannot know at build time what we will be asked to do by a previous firmware phase.
Really, I don't want to have to care about the binman binding. If it is u-boot specific, then it should stay in u-boot. I took /options/u-boot/, but now I'm starting to have second thoughts on that being in dtschema if it is going to be continually and frequently extended. Validating it in SR does little. If a vendor is abusing /options/u-boot/ in some way they could just as easily remove the node in their u-boot fork to pass. SR is certainly not going to require the node be there.
On A/B updates, that really doesn't seem like a u-boot specific problem to me. No one wants A/B updates in EDK2 or anything else?
A/B updates might be implemented in EDK2 or any other bootloader that chooses to implement it. The metadata information a bootloader needs to implement it are documented here [0]. Those metadata are not part of the DT. If they were it would make sense to add them on the schema. The DT entry we are using though serves a different purpose. It tells the bootloader the location of the metadata (iow where can I read them from the disk). Since bootloaders have a different way of storing their configuration, I don't think this needs to be in the spec. EDK2 for example doesn't always use a DT and I don't think they'll ever use it to store configuration information.
In another thread with Rob involved, we are trying to provide bindings for EDK2 to use.
Whatever the efforts of those trying to fragment the firmware industry, there are efforts to bring it together with a consistent configuration story. Ultimately I believe these will have to prevail, as the complexity increases.
Regards /Ilias