Re: [PATCH V7 4/6] kbuild: Add support to build overlays (%.dtbo)

Hi Viresh,

On Fri, Feb 5, 2021 at 10:55 AM Viresh Kumar [off-list ref] wrote:

On 05-02-21, 10:41, Geert Uytterhoeven wrote:

quoted

On Fri, Feb 5, 2021 at 10:25 AM Viresh Kumar [off-list ref] wrote:

quoted

On 05-02-21, 10:02, Geert Uytterhoeven wrote:

quoted

Thanks for your patch
(which I only noticed because it appeared in dt-rh/for-next ;-)

On Fri, Jan 29, 2021 at 8:31 AM Viresh Kumar [off-list ref] wrote:

quoted

Add support for building DT overlays (%.dtbo). The overlay's source file
will have the usual extension, i.e. .dts, though the blob will have

Why use .dts and not .dtso for overlays?
Because you originally (until v5) had a single rule for building .dtb
and .dtbo files?

I am fine with doing that as well if Rob and David agree to it. Rob
did suggest that at one point but we didn't do much about it later on
for some reason.

FWIW, this will also require a change in the DTC compiler.

Care to explain why? I've been using .dtsi for ages in
https://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git/log/?h=topic/renesas-overlays

I don't see you building them anywhere, they aren't added to the
Makefile ever. What am I missing ?

actually none of the dtso's were added to any makefile in that branch.

E.g. "ARM: dts: Build all overlays if OF_OVERLAY=y"?
https://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git/commit/?h=topic/renesas-overlays&id=597ee90971687a45678cca8d16bf624d174a99eb

Anyway, the DTC needs to know how to treat the dtso format and it will
error out currently with unknown format kind of errors.

Below email [1] have some information on the kind of changes required
here. Also note that we had to do similar changes for dtbo earlier
[2].

--
viresh

[1] https://lore.kernel.org/lkml/CAK7LNASViCOTGR7yDTfh0O+PAu+X-P2NwdY4oPMuXrr51awafA@mail.gmail.com/ (local)

-@ is handled by "kbuild: Enable DT symbols when CONFIG_OF_OVERLAY is used"
https://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git/commit/?h=topic/renesas-overlays&id=91e9d998514f3743125a707013a30d5f83054579

[2] https://lore.kernel.org/lkml/30fd0e5f2156665c713cf191c5fea9a5548360c0.1609926856.git.viresh.kumar@linaro.org/ (local)

I never had a need for those changes to dtc. .dtso/.dtbo work fine regardless.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds