[PATCH v4 00/15] OpenSBI Kconfig Support

[Anup Patel]

On Mon, Aug 1, 2022 at 5:05 PM Andrew Jones <ajones at ventanamicro.com> wrote:
>
> On Sun, Jul 31, 2022 at 10:26:38AM +0530, Anup Patel wrote:
> > In future, we will see more drivers in OpenSBI for system reset, serial port,
> > power management, etc platform specific devices. We need platform specific
> > compile time configuration to allow users control the size of OpenSBI generic
> > firmware binaries by only enabling desired drivers. In other words, users
> > should be allowed to restrict the set of RISC-V platforms on which OpenSBI
> > generic firmwares built by them can run.
> >
> > To address above, we add Kconfig support for OpenSBI platforms using the
> > Kconfiglib project which is a standalone kconfig parser.
> >
> > To try OpenSBI Kconfig support with generic platform, here are few
> > example commands:
> > make PLATFORM=generic             <-- builds OpenSBI using "defconfig"
> > make PLATFORM=generic menuconfig  <-- launches graphical interface for changes
> >
> > These patches can also be found in the kconfig_v4 branch at:
> > https://github.com/avpatel/opensbi.git
> >
> > Changes since v3:
> >  - Strip down the Kconfiglib sources added by PATCH1
> >  - Removed extra "." in the top-level Makefile updated by PATCH2
> >
> > Changes since v2:
> >  - Use $(FOO) instead of $FOO to access FOO environment variable in
> >    Kconfig files.
> >  - Added a new PATCH1 to include Kconfiglib v14.1.0 sources under
> >    the scripts directory of OpenSBI.
> >
> > Changes since v1:
> >  - Fix SPDX license specifier in new Kconfig files
> >
>
> Hi Anup,
>
> I played with this a bit and noticed a new compiler warning when compiling
> with clang.
>
> ...
>  GEN-DEP   platform/generic/platform_override_modules.dep
>  GEN-DEP   platform/generic/platform_override_modules.dep
>  CC-DEP    platform/generic/platform.dep
> /home/drew/code/github/opensbi/platform/generic/platform.c:10:10: fatal error: 'libfdt.h' file not found
> #include <libfdt.h>
>          ^~~~~~~~~~
> 1 error generated.
> ...

Okay, I will fix this in the next revision.

>
> I also noticed a bunch of directories and empty .h files (including
> libfdt.h) get added to build/platform/generic/kconfig/. That seems
> like a bug.

Those empty generated headers are used by kconfiglib to track which
kconfig option changed.

>
> I also tested the new PLATFORM_DEFCONFIG make variable. I found I needed
> to specify a defconfig file by a relative path to
> platform/$PLATFORM/configs/. I think it would be more convenient if
> the path could be relative to the root where 'make' is run. And, also
> nice would be if it could be an absolute path. Currently an absolute path
> is still assumed to be relative to platform/$PLATFORM/configs/ resulting
> in something like platform/$PLATFORM/configs//$ABSOLUTE_PATH

This path is relative to platform directory because:
1) defconfigs are separate for each platform
2) OpenSBI supports out-of-tree platform directories as well. For example,
   we can have some <xyz> platform outside OpenSBI sources so to
   build such a platform we use "PLATFORM_DIR=<absolute_path_of_xyz>"
   instead of "PLATFORM=xyz".

>
> Finally, I find it a bit strange that we can now specifically configure
> the '"Generic" version 0.1' platform type but still end up with a
> '"Generic" version 0.1' platform type. I think we should allow, or
> even enforce, configured generic platforms to have new names and
> versions.

Okay, I will add a separate patch for this in the next revision.

>
> Thanks,
> drew

Regards,
Anup