[PATCH v1 1/7] RISC-V: introduce ARCH_FOO kconfig aliases for SOC_FOO symbols

[Geert Uytterhoeven]

Hi Conor,

On Tue, Jan 10, 2023 at 10:40 PM Conor Dooley <conor at kernel.org> wrote:
> On Tue, Jan 10, 2023 at 10:14:51PM +0100, Geert Uytterhoeven wrote:
> > On Mon, Nov 21, 2022 at 11:18 PM Conor Dooley <conor at kernel.org> wrote:
> > > From: Conor Dooley <conor.dooley at microchip.com>
> > >
> > > To facilitate a transfer from SOC_FOO to ARCH_FOO, over a release cycle,
> > > introduce some aliases so that drivers etc that use the SOC_FOO symbols
> > > can be converted.
> > >
> > > Signed-off-by: Conor Dooley <conor.dooley at microchip.com>
> >
> > Thanks for your patch, which is now commit fc43211939bb6874
> > ("RISC-V: kconfig.socs: convert usage of SOC_CANAAN to
> > ARCH_CANAAN") in riscv/for-next
>
> I see this and I immediately know it is going to be bad news!
>
> > > --- a/arch/riscv/Kconfig.socs
> > > +++ b/arch/riscv/Kconfig.socs
> >
> > > @@ -73,6 +91,9 @@ config SOC_CANAAN_K210_DTB_BUILTIN
> > >           This option should be selected if no bootloader is being used.
> > >           If unsure, say Y.
> > >
> > > +config ARCH_CANAAN_K210_DTB_SOURCE
> > > +       def_bool SOC_CANAAN_K210_DTB_SOURCE
> >
> > This is not correct, as SOC_CANAAN_K210_DTB_SOURCE below is
> > not a bool, but a string.
> >
> > > +
> > >  config SOC_CANAAN_K210_DTB_SOURCE
> > >         string "Source file for the Canaan Kendryte K210 builtin DTB"
> > >         depends on SOC_CANAAN
> >
> > Hence
> >
> >     obj-$(CONFIG_ARCH_CANAAN_K210_DTB_BUILTIN) += $(addsuffix .dtb.o,
> > $(CONFIG_ARCH_CANAAN_K210_DTB_SOURCE))
> >
> > will do the wrong thing later, and I get a non-bootable system (no output)
> > on my MAiX-BiT.
> >
> > Unfortunately there is no def_string, so I don't think we can fix this
> > in a backwards-compatible way, and have to replace all
> > SOC_CANAAN_K210_DTB_SOURCE by ARCH_CANAAN_K210_DTB_SOURCE,
> > and urging users to update their .config manually.
>
> That sucks. I'm not sure how I missed this - I had tested originally on
> my k210, but evidently there was something wrong with how I had done it.
> I must have not tested a subsequent revision on the k210. Mea cupla.
>
> As it wasn't my intention to inflict this change without time for the
> symbols to appear in configs, my immediate feeling is that this part of
> the change should be reverted.
>
> Of course, we could so something like:
> diff --git a/arch/riscv/Kconfig.socs b/arch/riscv/Kconfig.socs
> index 34a54e5310a1..d36a5f39f13a 100644
> --- a/arch/riscv/Kconfig.socs
> +++ b/arch/riscv/Kconfig.socs
> @@ -79,7 +79,8 @@ config SOC_CANAAN_K210_DTB_BUILTIN
>           If unsure, say Y.
>
>  config ARCH_CANAAN_K210_DTB_SOURCE
> -       def_bool SOC_CANAAN_K210_DTB_SOURCE
> +       string
> +       default SOC_CANAAN_K210_DTB_SOURCE

Thanks, that works!
I guess it was too late in the evening for me, to realize that the lack of
"def_string" can be worked around using "string" and "default".

>  config SOC_CANAAN_K210_DTB_SOURCE
>         string "Source file for the Canaan Kendryte K210 builtin DTB"
>
> But I am not sure of how that interacts with the various methods of
> updating ones config.
> From, admittedly limited, testing it does get updated if
> SOC_CANAAN_K210_DTB_SOURCE is changed using menuconfig. Similarly, if
> one alters that symbol and does olddefconfig it also gets updated.

With the above, the value of SOC_CANAAN_K210_DTB_SOURCE in existing
config files will be copied to ARCH_CANAAN_K210_DTB_SOURCE when running
"make oldconfig".
Hence in v6.4 you can drop the old SOC_CANAAN_K210_DTB_SOURCE.  As that
symbol is not present in defconfigs, there is nothing to update there,

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at 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