LoongArch: Enable initial Rust support

  Add initial Rust support for LoongArch.

Signed-off-by: WANG Rui <wangrui@loongson.cn>
---
 Documentation/rust/arch-support.rst |  1 +
 arch/loongarch/Kconfig              |  1 +
 arch/loongarch/Makefile             |  3 +++
 scripts/generate_rust_target.rs     | 10 ++++++++++
 4 files changed, 15 insertions(+)
  

Hi WANG,

kernel test robot noticed the following build warnings:

[auto build test WARNING on rust/rust-next]
[also build test WARNING on linus/master v6.7-rc8 next-20240105]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/WANG-Rui/LoongArch-Enable-initial-Rust-support/20240106-150902
base:   https://github.com/Rust-for-Linux/linux rust-next
patch link:    https://lore.kernel.org/r/20240106065941.180796-1-wangrui%40loongson.cn
patch subject: [PATCH] LoongArch: Enable initial Rust support
reproduce: (https://download.01.org/0day-ci/archive/20240107/202401070815.6tdJWFme-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202401070815.6tdJWFme-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> Documentation/rust/arch-support.rst:18: WARNING: Malformed table.

vim +18 Documentation/rust/arch-support.rst

    14	
    15	============  ================  ==============================================
    16	Architecture  Level of support  Constraints
    17	============  ================  ==============================================
  > 18	``loongarch`` Maintained
  

On Sun, Jan 7, 2024 at 9:06 AM kernel test robot <lkp@intel.com> wrote:
>
> Hi WANG,
>
> kernel test robot noticed the following build warnings:
>
> [auto build test WARNING on rust/rust-next]
> [also build test WARNING on linus/master v6.7-rc8 next-20240105]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
>
> url:    https://github.com/intel-lab-lkp/linux/commits/WANG-Rui/LoongArch-Enable-initial-Rust-support/20240106-150902
> base:   https://github.com/Rust-for-Linux/linux rust-next
> patch link:    https://lore.kernel.org/r/20240106065941.180796-1-wangrui%40loongson.cn
> patch subject: [PATCH] LoongArch: Enable initial Rust support
> reproduce: (https://download.01.org/0day-ci/archive/20240107/202401070815.6tdJWFme-lkp@intel.com/reproduce)
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202401070815.6tdJWFme-lkp@intel.com/
>
> All warnings (new ones prefixed by >>):
>
> >> Documentation/rust/arch-support.rst:18: WARNING: Malformed table.
>
> vim +18 Documentation/rust/arch-support.rst
>
>     14
>     15  ============  ================  ==============================================
>     16  Architecture  Level of support  Constraints
>     17  ============  ================  ==============================================
>   > 18  ``loongarch`` Maintained
I think we can put a "none." or just a "-" below "Constraints" to fix
the warning.

Huacai
>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki
>
  

On Sat, Jan 6, 2024 at 8:04 AM WANG Rui <wangrui@loongson.cn> wrote:
>
>  ============  ================  ==============================================
>  Architecture  Level of support  Constraints
>  ============  ================  ==============================================
> +``loongarch`` Maintained

On top of what Huacai said, it would be nice to add another character
and realign the table so that `loongarch` it doesn't overflow (perhaps
best done in an additional, previous patch).

> +    } else if cfg.has("LOONGARCH") {

Would it be possible to do it without a custom target in
`scripts/generate_rust_target.rs`? If it is not possible (e.g. there
is something that you cannot tweak otherwise on top of a built-in
target via the CLI flags), it is fine to use a custom target for the
moment.

For instance, this is how ARM is doing it:
https://lore.kernel.org/rust-for-linux/20231020155056.3495121-1-Jamie.Cunliffe@arm.com/

Thanks!

Cheers,
Miguel
  

Hello,

On Sun, Jan 7, 2024 at 10:29 PM Miguel Ojeda
<miguel.ojeda.sandonis@gmail.com> wrote:
>
> On Sat, Jan 6, 2024 at 8:04 AM WANG Rui <wangrui@loongson.cn> wrote:
> >
> >  ============  ================  ==============================================
> >  Architecture  Level of support  Constraints
> >  ============  ================  ==============================================
> > +``loongarch`` Maintained
>
> On top of what Huacai said, it would be nice to add another character
> and realign the table so that `loongarch` it doesn't overflow (perhaps
> best done in an additional, previous patch).

Thanks Huacai, Miguel.

>
> > +    } else if cfg.has("LOONGARCH") {
>
> Would it be possible to do it without a custom target in
> `scripts/generate_rust_target.rs`? If it is not possible (e.g. there
> is something that you cannot tweak otherwise on top of a built-in
> target via the CLI flags), it is fine to use a custom target for the
> moment.
>
> For instance, this is how ARM is doing it:
> https://lore.kernel.org/rust-for-linux/20231020155056.3495121-1-Jamie.Cunliffe@arm.com/
>

Thanks for your comments. I noticed that the refactoring of the build
system to support the use of Rust built-in targets is still ongoing.
Could this take some time? In the meantime, let's proceed with the
generation method.

> Thanks!
>
> Cheers,
> Miguel
>
  

On Mon, Jan 8, 2024 at 4:22 AM WANG Rui <wangrui@loongson.cn> wrote:
>
> Thanks for your comments. I noticed that the refactoring of the build
> system to support the use of Rust built-in targets is still ongoing.
> Could this take some time? In the meantime, let's proceed with the
> generation method.

My pleasure! If you mean the first patch of the arm64 series I linked,
we have been waiting for a while for that to get merged (hopefully
6.9?). So, yeah, as you say, it is probably best to continue with this
and then you can change it later after the arm64 series lands. Thanks!

Cheers,
Miguel
  

On Wed, Jan 10, 2024 at 7:21 PM Miguel Ojeda
<miguel.ojeda.sandonis@gmail.com> wrote:
>
> On Mon, Jan 8, 2024 at 4:22 AM WANG Rui <wangrui@loongson.cn> wrote:
> >
> > Thanks for your comments. I noticed that the refactoring of the build
> > system to support the use of Rust built-in targets is still ongoing.
> > Could this take some time? In the meantime, let's proceed with the
> > generation method.
>
> My pleasure! If you mean the first patch of the arm64 series I linked,
> we have been waiting for a while for that to get merged (hopefully
> 6.9?). So, yeah, as you say, it is probably best to continue with this
> and then you can change it later after the arm64 series lands. Thanks!

Thanks. I'll do it.

Regards,
Rui

>
> Cheers,
> Miguel
>