Re: [Buildroot] [PATCH] package/pixman: Specify riscv dependency

[Thomas Petazzoni via buildroot <buildroot@buildroot.org>]

Hello Charlie,

On Thu, 10 Apr 2025 18:08:26 -0700
Charlie Jenkins <charlie@rivosinc.com> wrote:

> riscv Pixman depends on COMPAT_HWCAP_ISA_V which is available in Linux
> 6.4+, so make Pixman dependent on headers that are at least 6.4.
> 
> Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>

Thanks for this patch! Do you have a reference/explanation?

One issue with adding such a dependency is that it needs to be
propagated to ALL reverse dependencies of pixman, and there are a LOT
of them. Like doing this:

diff --git a/pixman/pixman-riscv.c b/pixman/pixman-riscv.c
index 1f0440f..7b44ece 100644
--- a/pixman/pixman-riscv.c
+++ b/pixman/pixman-riscv.c
@@ -44,7 +44,7 @@ detect_cpu_features (void)
 {
     riscv_cpu_features_t features = 0;
 
-#if defined(__linux__)
+#if defined(__linux__) && defined(COMPAT_HWCAP_ISA_V)
     if (getauxval (AT_HWCAP) & COMPAT_HWCAP_ISA_V)
     {
        features |= RVV;

In the pixman code base would resolve the build issue, and is I believe
acceptable upstream.

But apparently, the issue is that <sys/auxv.h> doesn't exist at all. In
this case, you can add a meson check for this header file.

Also, it would be nice to indicate in the commit message which version
of pixman introduced the issue, apparently pixman-0.44.0.

Could you respin an updated version, that uses a patch against pixman,
and make sure that patch gets submitted upstream?

Also, indicate in your commit message:

Fixes:

  http://autobuild.buildroot.net/results/4ecdf5320716ec8b39f09fde3fcbbdcdb557f8ab/

Thanks a lot!

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