ci: implement debian-cross-riscv64

Revival of my old effort to get riscv64 testing in!
Now we're at Debian 13 (trixie), we can support RISC-V builds!

Disable llvmpipe suite because of lp_test_arit failure, see
https://gitlab.freedesktop.org/mesa/mesa/-/issues/14123

Signed-off-by: David Heidelberg <david@ixit.cz>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/37445>

.gitlab-ci/container/create-cross-file.sh

@@ -22,6 +22,8 @@ elif [[ "$arch" = "i386" ]]; then
     rust_target=i686-unknown-linux-gnu
 elif [[ "$arch" = "ppc64el" ]]; then
     rust_target=powerpc64le-unknown-linux-gnu
+elif [[ "$arch" = "riscv64" ]]; then
+    rust_target=riscv64gc-unknown-linux-gnu
 elif [[ "$arch" = "s390x" ]]; then
     rust_target=s390x-unknown-linux-gnu
 else

.gitlab-ci/container/debian/gitlab-ci.yml

@@ -121,6 +121,30 @@ debian/ppc64el_build:
     - job: debian/ppc64el_build
       optional: true
 
+# Debian based RISC-V 64 cross-build image
+debian/riscv64_build:
+  extends:
+    - .use-debian/x86_64_build-base
+  variables:
+    MESA_IMAGE_TAG: &debian-riscv64_build ${DEBIAN_BUILD_TAG}
+    LLVM_VERSION: &debian-riscv64-llvm 19
+
+.use-debian/riscv64_build:
+  tags:
+    - $FDO_RUNNER_JOB_PRIORITY_TAG_X86_64
+  extends:
+    - .set-image-base-tag
+  variables:
+    MESA_BASE_TAG: *debian-x86_64_build-base
+    MESA_IMAGE_PATH: "debian/riscv64_build"
+    MESA_IMAGE_TAG: *debian-riscv64_build
+    LLVM_VERSION: *debian-riscv64-llvm
+  needs:
+    - job: sanity
+      optional: true
+    - job: debian/riscv64_build
+      optional: true
+
 # Debian based s390x cross-build image
 debian/s390x_build:
   extends:

.gitlab-ci/container/debian/riscv64_build.sh

@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+
+set -e
+
+. .gitlab-ci/setup-test-env.sh
+
+arch=riscv64
+
+# Ephemeral packages (installed for this script and removed again at the end)
+EPHEMERAL=(
+    libssl-dev
+)
+
+apt-get -y install "${EPHEMERAL[@]}"
+
+. .gitlab-ci/container/build-mold.sh
+
+apt-get purge -y "${EPHEMERAL[@]}"
+
+. .gitlab-ci/container/cross_build.sh