Hi Simon,
sjg@chromium.org wrote on Mon, 25 Sep 2023 06:33:14 -0600:
Hi Miquel,
On Mon, 25 Sept 2023 at 01:21, Miquel Raynal miquel.raynal@bootlin.com wrote:
Hi Simon,
sjg@chromium.org wrote on Fri, 22 Sep 2023 13:51:14 -0600:
Hi Rob,
On Fri, 22 Sept 2023 at 13:43, Rob Herring robh@kernel.org wrote:
On Fri, Sep 22, 2023 at 1:12 PM Simon Glass sjg@chromium.org wrote:
Hi Rob,
On Fri, 22 Sept 2023 at 11:46, Rob Herring robh@kernel.org wrote:
On Fri, Sep 22, 2023 at 11:01:18AM -0600, Simon Glass wrote: > Hi Rob, > > On Fri, 22 Sept 2023 at 10:00, Rob Herring robh@kernel.org wrote: > > > > On Thu, Sep 21, 2023 at 1:45 PM Simon Glass sjg@chromium.org wrote: > > > > > > Binman[1] is a tool for creating firmware images. It allows you to > > > combine various binaries and place them in an output file. > > > > > > Binman uses a DT schema to describe an image, in enough detail that > > > it can be automatically built from component parts, disassembled, > > > replaced, listed, etc. > > > > > > Images are typically stored in flash, which is why this binding is > > > targeted at mtd. Previous discussion is at [2] [3]. > > > > > > [1] https://u-boot.readthedocs.io/en/stable/develop/package/binman.html > > > [2] https://lore.kernel.org/u-boot/20230821180220.2724080-3-sjg@chromium.org/ > > > [3] https://www.spinics.net/lists/devicetree/msg626149.html > > > > You missed: > > > > https://github.com/devicetree-org/dt-schema/pull/110 > > > > where I said: We certainly shouldn't duplicate the existing partitions > > bindings. What's missing from them (I assume we're mostly talking > > about "fixed-partitions" which has been around forever I think (before > > me))? > > > > To repeat, unless there is some reason binman partitions conflict with > > fixed-partitions, you need to start there and extend it. From what's > > posted here, it neither conflicts nor needs extending. > > I think at this point I am just hopelessly confused. Have you taken a > look at the binman schema? [1]
Why do I need to? That's used for some tool and has nothing to do with a device's DTB. However, I thought somewhere in this discussion you showed it under a flash device node.
Yes, that is the intent (under a flash node).
Then I care because then it overlaps with what we already have for partitions. If I misunderstood that, then just put your schema with your tool. Only users of the tool should care about the tool's schema.
OK. I believe that binman will fit into both camps, since its input is not necessarily fully formed. E.g. if you don't specify the offset of an entry, then it will be packed automatically. But the output is fully formed, in that Binman now knows the offset so can write it to the DT.
I suppose it could take its own format as input and then write out something different for the "on the device" format (i.e. fixed-partitions). At least for the dynamic offsets, we may need something allowed for binman input, but not allowed on device. In general, there is support for partitions without addresses/offsets, but only for partitions that have some other way to figure that out (on disk partition info).
There's also the image filename which doesn't really belong in the on device partitions. So maybe the input and output schemas should be separate.
OK, I'll focus on the output schema for now. I suspect this will be a grey area though.
As an example, if you replace a binary in the firmware, Binman can repack the firmware to make room, respecting the alignment and size constraints. So these need to be in the output schema somehow.
> I saw this file, which seems to extend a partition. > > Documentation/devicetree/bindings/mtd/partitions/brcm,bcm4908-partitions.yaml
IIRC, that's a different type where partition locations are stored in the flash, so we don't need location and size in DT.
OK.
> > I was assuming that I should create a top-level compatible = "binman" > node, with subnodes like compatible = "binman,bl31-atf", for example. > I should use the compatible string to indicate the contents, right?
Yes for subnodes, and we already have some somewhat standard ones for "u-boot" and "u-boot-env". Though historically, "label" was used.
Binman has common properties for all entries, including "compress" which sets the compression algorithm.
I see no issue with adding that. It seems useful and something missing in the existing partition schemas.
OK I sent a patch with that.
So perhaps I should start by defining a new binman,bl31-atf which has common properties from an "binman,entry" definition?
I don't understand the binman prefix. The contents are ATF (or TF-A now). Who wrote it to the flash image is not relevant.
Are you suggesting just "atf-bl31", or "arm,atf-bl31" ? Or should we change it to "tfa-bl31"?
I don't really understand the relationship with TF-A here. Can't we just have a kind of fixed-partitions with additional properties like the compression?
Binman needs to know what to put in there, which is the purpose of the compatible string.
But "what" should be put inside the partition is part of the input argument, not the output. You said (maybe I got this wrong) that the schema would apply to the output of binman. If you want to let user know what's inside, maybe it is worth adding a label, but otherwise I don't like the idea of a compatible for that, which for me would mean: "here is how to handle that specific portion of the flash/here is how the flash is organized".
We already have some compatibles in use. We should reuse them if possible. Not sure about TF-A though.
OK.
Also, I still don't understand the purpose of this schema. So binman generates an image, you want to flash this image and you would like the tool to generate the corresponding (partition) DT snippet automatically. Do I get this right? I don't get why you would need new compatibles for that.
It is actually the other way around. The schema tells Binman how to build the image (what goes in there and where). Then outputs an updated DT which describes where everything ended up, for use by other tools, e.g. firmware update. It is a closed loop in that sense. See the references for more information.
Maybe I fail to see why you would want these description to be introduced here, if they are not useful to the OS.
[1] https://u-boot.readthedocs.io/en/latest/develop/package/index.html [2] https://pretalx.com/media/osfc2019/submissions/Y7EN9V/resources/Binman_-_A_d... [3] https://www.youtube.com/watch?v=L84ujgUXBOQ
Thanks, Miquèl