lkl: enable clang cross compiled FreeBSD build

Add script to create a FreeBSD sysroot and enable clang based
build.

Builds are enabled in CI as well, but tests are not yet enabled.

Signed-off-by: Octavian Purdila <tavip@google.com>

Author: tavip

.github/workflows/ci.yml

@@ -38,6 +38,12 @@ jobs:
             runs_on: ubuntu-22.04
             shell: bash
             build_options: "LLVM=1 CROSS_COMPILE=x86_64-linux-gnu"
+          - displayTargetName: freebsd
+            os: unix
+            runs_on: ubuntu-22.04
+            shell: bash
+            build_options: "LLVM=1 CROSS_COMPILE=x86_64-unknown-freebsd SYSROOT=~/freebsd-sysroot"
+            make_sysroot: "./tools/lkl/scripts/freebsd-make-sysroot.sh"
     timeout-minutes: 100
     env:
       CCACHE_DIR: ${{ github.workspace }}/.ccache
@@ -150,10 +156,14 @@ jobs:
           echo MYSSH="$MYSSH" >> $GITHUB_ENV
           echo MYSCP="$MYSCP" >> $GITHUB_ENV
           echo LKL_QEMU_TEST=1 >> $GITHUB_ENV
+      - name: Make sysroot
+        run: |
+          ${{ matrix.make_sysroot }}
       - name: Build
         run: |
           make -j4 -C tools/lkl ${{ matrix.build_options }}
       - name: Tests
+        if: matrix.displayTargetName != 'freebsd'
         run: mkdir junit && make -C tools/lkl run-tests tests="--junit-dir ../../junit"
       - name: Save test results
         uses: actions/upload-artifact@v5

tools/lkl/Makefile.autoconf

@@ -139,7 +139,8 @@ endef
 
 define llvm_target_to_ld_fmt
   $(if $(filter $(CROSS_COMPILE),x86_64-linux-gnu),elf64-x86-64,\
-    $(error Unsupported LLVM target $(CROSS_COMPILE)))
+    $(if $(filter $(CROSS_COMPILE),x86_64-unknown-freebsd),elf64-x86-64-freebsd, \
+    $(error Unsupported LLVM target $(CROSS_COMPILE))))
 endef
 
 define llvm_sysroot

tools/lkl/scripts/freebsd-make-sysroot.sh

@@ -0,0 +1,24 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+function package_path()
+{
+  grep \"name\":\"$1\" packagesite.yaml | jq -r .repopath
+}
+
+mkdir -p ~/freebsd-sysroot
+cd ~/freebsd-sysroot
+wget -q https://download.freebsd.org/releases/amd64/14.4-RELEASE/base.txz
+tar -xf base.txz --exclude='./dev/*' --exclude='./chroot/*'
+
+# Get FreeBSD package index...
+wget -q https://pkg.freebsd.org/FreeBSD:14:amd64/latest/packagesite.pkg
+tar -xf packagesite.pkg packagesite.yaml
+
+wget -q https://pkg.freebsd.org/FreeBSD:14:amd64/latest/$(package_path argp-standalone)
+wget -q https://pkg.freebsd.org/FreeBSD:14:amd64/latest/$(package_path fusefs-libs3)
+
+tar -xf argp-standalone-*.pkg
+tar -xf fusefs-libs3-*.pkg
+
+rm fusefs-libs3-*.pkg argp-standalone-*.pkg base.txz packagesite.pkg packagesite.yaml