Hi Tom,
On Mon, 1 Nov 2021 at 12:07, Tom Rini trini@konsulko.com wrote:
On Mon, Nov 01, 2021 at 06:33:35PM +0100, François Ozog wrote:
Hi Simon
Le lun. 1 nov. 2021 à 17:58, Simon Glass sjg@chromium.org a écrit :
Hi Peter,
On Mon, 1 Nov 2021 at 04:48, Peter Maydell peter.maydell@linaro.org wrote:
On Tue, 26 Oct 2021 at 01:33, Simon Glass sjg@chromium.org wrote:
Add this file, generated from qemu, so there is a reference devicetree in the U-Boot tree.
Signed-off-by: Simon Glass sjg@chromium.org
Note that the dtb you get from QEMU is only guaranteed to work if:
- you run it on the exact same QEMU version you generated it with
- you pass QEMU the exact same command line arguments you used when you generated it
Yes, I certainly understand that. In general this is not safe, but in practice it works well enough for development and CI.
You recognize that you hijack a product directory with development hack facility. There is a test directory to keep things clear. There can be a dev-dts or something similar for Dev time tools. I have only seen push back on those fake dts files in the dts directory: I guess that unless someone strongly favors a continuation of the discussion, you may consider re-shaping the proposal to address concerns.
Yes. We need to document how to make development easier. But I'm still not on board with the notion of including DTS files for platforms where the source of truth for the DTB is elsewhere. That's going to bring us a lot more pain.
Are you talking about QEMU specifically, or Raspberry Pi?
How can we get this resolved? I very much want to get to just having OF_SEPARATE and OF_EMBED as the only available build-time options, with OF_BOARD (and perhaps OF_PASSAGE) as something we can enable for runtime support. I feel that separating the build-time and run-time behaviour is very important. Over time perhaps we will have some success in upstreaming bindings, but for now we have what we have. There is still a lot of pushback on U-Boot having things in the devicetree, although I do see that softening somewhat.
It is important to make sure our "develop our project" workflow is sane and relatively pain free. But that needs to not come by making sacrifices to the "use our project" outcome. I would hope for example that the new Pi zero platform is just dtb changes, as far as the linux kernel is concerned which means that for rpi_arm64 (which uses run time dtb) it also just works. And that's what we want to see.
So long as OF_BOARD is enabled then the flow should work as you expect.
Regards, Simon