[Buildroot] [PATCH 1/1] package/x11r7/xlib_libxshmfence: disable on riscv32

[Arnout Vandecappelle]

On 05/08/2021 13:21, Fabrice Fontaine wrote:
> xlib_libxshmfence unconditionally uses SYS_futex which raises the
> following build failure on riscv32:
> 
> xshmfence_futex.h:58:17: error: 'SYS_futex' undeclared (first use in this function); did you mean 'sys_futex'?
>    58 |  return syscall(SYS_futex, addr1, op, val1, timeout, addr2, val3);
>       |                 ^~~~~~~~~
>       |                 sys_futex

 The proper way is to add support for futex64, but:

- that's a bit complicated so better for upstream to do;
- Linux on RISCV32 doesn't have much of a future, except on FPGAs which aren't
very likely to run X;
- X itself doesn't have much of a future either;
- we're in the stabilization period so risky patches are to be avoided.

 Therefore, applied to master, thanks.

> 
> Fixes:
>  - http://autobuild.buildroot.org/results/b3523e35fde0fac04b96a6278cbc6ffdfe56f7d1
> 
> Signed-off-by: Fabrice Fontaine <fontaine.fabrice at gmail.com>
> ---
>  package/mesa3d/Config.in                    | 3 ++-
>  package/x11r7/xlib_libxshmfence/Config.in   | 1 +
>  package/x11r7/xserver_xorg-server/Config.in | 3 ++-
>  3 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/package/mesa3d/Config.in b/package/mesa3d/Config.in
> index 41c90c49af..eb7c1eef46 100644
> --- a/package/mesa3d/Config.in
> +++ b/package/mesa3d/Config.in
> @@ -65,7 +65,8 @@ config BR2_PACKAGE_MESA3D_DRI_DRIVER
>  		!BR2_PACKAGE_MESA3D_OPENGL_GLX && \
>  		!BR2_PACKAGE_MESA3D_OPENGL_EGL
>  	select BR2_PACKAGE_XLIB_LIBXSHMFENCE if \
> -		(BR2_PACKAGE_XORG7 && BR2_TOOLCHAIN_HAS_SYNC_4)
> +		(BR2_PACKAGE_XORG7 && BR2_TOOLCHAIN_HAS_SYNC_4 && \
> +			!BR2_RISCV_32)
>  
>  config BR2_PACKAGE_MESA3D_VULKAN_DRIVER
>  	bool
> diff --git a/package/x11r7/xlib_libxshmfence/Config.in b/package/x11r7/xlib_libxshmfence/Config.in
> index 710476b357..55cd91d1e4 100644
> --- a/package/x11r7/xlib_libxshmfence/Config.in
> +++ b/package/x11r7/xlib_libxshmfence/Config.in
> @@ -1,5 +1,6 @@
>  config BR2_PACKAGE_XLIB_LIBXSHMFENCE
>  	bool "libxshmfence"
> +	depends on !BR2_RISCV_32

 I added a comment to make it explicit that it can be removed when upstream adds
support for futex64.

 Regards,
 Arnout

>  	depends on BR2_TOOLCHAIN_HAS_SYNC_4
>  	select BR2_PACKAGE_XORGPROTO
>  	help
> diff --git a/package/x11r7/xserver_xorg-server/Config.in b/package/x11r7/xserver_xorg-server/Config.in
> index fcd3d0ae00..4dc15435a8 100644
> --- a/package/x11r7/xserver_xorg-server/Config.in
> +++ b/package/x11r7/xserver_xorg-server/Config.in
> @@ -53,7 +53,8 @@ config BR2_PACKAGE_XSERVER_XORG_SERVER_MODULAR
>  	depends on BR2_INSTALL_LIBSTDCPP
>  	select BR2_PACKAGE_LIBDRM
>  	select BR2_PACKAGE_LIBPCIACCESS
> -	select BR2_PACKAGE_XLIB_LIBXSHMFENCE if BR2_TOOLCHAIN_HAS_SYNC_4
> +	select BR2_PACKAGE_XLIB_LIBXSHMFENCE if \
> +		(BR2_TOOLCHAIN_HAS_SYNC_4 && !BR2_RISCV_32)
>  	help
>  	  This variant of the X.org server is the full-blown variant,
>  	  as used by desktop GNU/Linux distributions. The drivers (for
>