[PATCH V3 02/10] init.h: Fix the __setup_param() macro for module build
Anson Huang
anson.huang at nxp.com
Wed Jul 1 05:27:07 EDT 2020
Hi, Arnd
> Subject: Re: [PATCH V3 02/10] init.h: Fix the __setup_param() macro for
> module build
>
> On Wed, Jul 1, 2020 at 7:14 AM Anson Huang <anson.huang at nxp.com>
> wrote:
> > > Subject: Re: [PATCH V3 02/10] init.h: Fix the __setup_param() macro
> > > for module build On Mon, Jun 29, 2020 at 1:40 PM Anson Huang
> > > <anson.huang at nxp.com>
> > > wrote:
> > > > It makes sense to drop the __setup() and __serup_param() in the
> > > > #else block, just use one definition for all cases, if no one
> > > > objects, I will remove
> > > them in next patch series.
> > >
> > > Ok, sounds good. Note that there may be users of the plain __setup()
> > > that just get turned into nops right now. Usually those are already
> > > enclosed in "#ifndef MODULE", but if they are not, then removing the
> > > definition would cause a build error.
> > >
> > > Have a look if you can find such instances, and either change the
> > > patch to add the missing "#ifndef MODULE" checks, or just drop the
> > > __setup_param() and leave the __setup() if it gets too complicated.
> >
> > Looks like the __setup_param() defined in "#ifndef MODULE" can NOT be
> > used for MODULE build at all, so sharing same implementation is NOT
> > available, so if it is NOT that critical, I plan to keep the #else
> > block in this patch, let me know if you have further concern or any
> > other suggestion, below is the build error reported for module build
> > using
> > __setup_param() implementation for built in.
>
> I don't understand what your plan is here. Do you mean you will leave that
> part of the clk driver as built-in?
I meant I will leave the #else block of __setup_param() defined as nothing as below to
make module build passed.
#define __setup_param(str, unique_id, fn, early) /* nothing */
>
> > In file included from ./arch/arm64/include/asm/alternative.h:12,
> > from ./arch/arm64/include/asm/lse.h:15,
> > from ./arch/arm64/include/asm/cmpxchg.h:14,
> > from ./arch/arm64/include/asm/atomic.h:16,
> > from ./include/linux/atomic.h:7,
> > from ./include/asm-generic/bitops/atomic.h:5,
> > from ./arch/arm64/include/asm/bitops.h:26,
> > from ./include/linux/bitops.h:29,
> > from ./include/linux/kernel.h:12,
> > from ./include/linux/clk.h:13,
> > from drivers/clk/imx/clk.c:2:
> > ./include/linux/init.h:177:16: error: variable
> ‘__setup_imx_keep_uart_earlycon’ has initializer but incomplete type
> > 177 | static struct obs_kernel_param __setup_##unique_id \
> > | ^~~~~~~~~~~~~~~~
> > drivers/clk/imx/clk.c:157:1: note: in expansion of macro ‘__setup_param’
> > 157 | __setup_param("earlycon", imx_keep_uart_earlycon,
> > | ^~~~~~~~~~~~~
> > ./include/linux/init.h:180:7: warning: excess elements in struct initializer
> > 180 | = { __setup_str_##unique_id, fn, early }
> > | ^~~~~~~~~~~~
> > drivers/clk/imx/clk.c:157:1: note: in expansion of macro ‘__setup_param’
> > 157 | __setup_param("earlycon", imx_keep_uart_earlycon,
> > | ^~~~~~~~~~~~~
> > ./include/linux/init.h:180:7: note: (near initialization for
> > ‘__setup_imx_keep_uart_earlycon’)
>
> This error just means you can't have a __setup_param() call in a loadable
> module, which we already knew. If you need to do something with the clocks
> early on, that has to be in built-in code and cannot be in a module. If you don't
> need that code, then you should just remove it from both the modular version
> and the built-in version.
>
> What is the purpose of that __setup_param() argument parsing in the clock
> driver?
>
We need the code for proper uart clock management of earlycon, from the code, it
is trying to keep console uart clock enabled during kernel boot up.
Thanks,
Anson
More information about the linux-arm-kernel
mailing list