[PATCH v5 06/26] arm: qemu: Add a devicetree file for qemu_arm64

[Simon Glass]

Hi François,

On Mon, 1 Nov 2021 at 11:33, François Ozog <francois.ozog at linaro.org> wrote:
>
> Hi Simon
>
> Le lun. 1 nov. 2021 à 17:58, Simon Glass <sjg at chromium.org> a écrit :
>>
>> Hi Peter,
>>
>> On Mon, 1 Nov 2021 at 04:48, Peter Maydell <peter.maydell at linaro.org> wrote:
>> >
>> > On Tue, 26 Oct 2021 at 01:33, Simon Glass <sjg at 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 at chromium.org>
>> >
>> > Note that the dtb you get from QEMU is only guaranteed to work if:
>> >  1) you run it on the exact same QEMU version you generated it with
>> >  2) 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.

As stated previously, I would like to have at least a sample DT
in-tree for all boards. I cannot see another way to get the Kconfig
options in line. If we are able to put these files somewhere else in
the future and get them out of U-Boot, with perhaps just an overlay
for development purposes, I'd be keen to see it. But for now, this is
where we are, I believe.

In this particular case, this is not just a dev hack. It is also for
CI tests which need to use a devicetree. See for example here:

https://patchwork.ozlabs.org/project/uboot/patch/20211101011734.1614781-15-sjg@chromium.org/
https://patchwork.ozlabs.org/project/uboot/patch/20211101011734.1614781-24-sjg@chromium.org/


>>
>> I am able to use
>> QEMU versions that differ by two years, partly because I am not trying
>> to do anything clever.
>>
>> I have sent a patch to add an indication of where the devicetree came
>> from, to help with visibility on this.

Regards,
Simon