Bug#1051168: gtk4: 4.12 regression: FTBFS on riscv64: multiple test failures

[Simon McVittie]

Control: tags -1 + pending

On Sun, 03 Sep 2023 at 20:26:31 +0200, Aurelien Jarno wrote:
> Investigation has shown that the issue is only present for the gl
> backend, but not the cairo backend. It is due to a difference of
> rendering between llvmpipe and softpipe. It seems the referenced in the
> testsuite is generated with it. Rebuilding gtk4 on amd64 with
> GALLIUM_DRIVER=softpipe trigger the same failures and resulting in
> identical png files as on riscv64.
> 
> While support for llvmpipe is being worked on, it is currently blocked
> because mesa uses the deprecated mcjit interface, which does not accept
> new architectures.

I had been surprised to see riscv64 having the same test failures as
mips64el, because unlike mips64el, we don't force any specific graphics
driver on riscv64 (we only do that on mips64el because its llvmpipe is
broken). But if riscv64 doesn't *have* llvmpipe, then it makes complete
sense that we'd see the same failures there.

> In the meantime, would it be possible to ignore the corresponding
> failures like it is done on mips*? I have tested the following patch:
>  
>  # https://bugs.debian.org/1050077
> -ifneq ($(filter mips%,$(DEB_HOST_ARCH_CPU)),)
> +ifneq ($(filter mips% riscv64,$(DEB_HOST_ARCH_CPU)),)

I'll apply at least that, but if new architectures can't have llvmpipe
for a while, then perhaps it would make more sense to apply the mips%
workaround to every architecture.

    smcv