[Buildroot] [PATCH 1/3] arch: add support for loongarch64

[Thomas Petazzoni]

On Tue, 14 May 2024 08:26:09 +0200
Waldemar Brodkorb <wbx at openadk.org> wrote:

> Signed-off-by: Waldemar Brodkorb <wbx at openadk.org>
> ---
>  arch/Config.in             | 12 ++++++++++++
>  arch/Config.in.loongarch64 | 14 ++++++++++++++
>  package/glibc/Config.in    |  1 +
>  package/musl/Config.in     |  1 +
>  4 files changed, 28 insertions(+)
>  create mode 100644 arch/Config.in.loongarch64

This needs an entry in the DEVELOPERS file.

Is this architecture supported in all versions of binutils/gcc/gdb we
support?

> diff --git a/arch/Config.in.loongarch64 b/arch/Config.in.loongarch64
> new file mode 100644
> index 0000000000..2b5bac095d
> --- /dev/null
> +++ b/arch/Config.in.loongarch64
> @@ -0,0 +1,14 @@
> +config BR2_ARCH
> +	default "loongarch64"
> +
> +config BR2_NORMALIZED_ARCH
> +	default "loongarch"
> +
> +config BR2_ENDIAN
> +	default "LITTLE"
> +
> +config BR2_READELF_ARCH_NAME
> +	default "LoongArch"
> +

Based on the gcc documentation, I see two -march values:

     ‘loongarch64’
          A generic CPU with 64-bit extensions.
     ‘la464’
          LoongArch LA464 CPU with LBT, LSX, LASX, LVZ.

And also 3 ABIs:

     ‘lp64d’
          Uses 64-bit general purpose registers and 32/64-bit
          floating-point registers for parameter passing.  Data model is
          LP64, where ‘int’ is 32 bits, while ‘long int’ and pointers
          are 64 bits.
     ‘lp64f’
          Uses 64-bit general purpose registers and 32-bit
          floating-point registers for parameter passing.  Data model is
          LP64, where ‘int’ is 32 bits, while ‘long int’ and pointers
          are 64 bits.
     ‘lp64s’
          Uses 64-bit general purpose registers and no floating-point
          registers for parameter passing.  Data model is LP64, where
          ‘int’ is 32 bits, while ‘long int’ and pointers are 64 bits.

Should we do something about this?

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com