[PATCH v2 2/2] oeqa/sdk: build the kernel's host tools with a host pkg-config

[Trevor Woerner <twoerner@gmail.com>]

The SDK environment sets PKG_CONFIG_SYSROOT_DIR, PKG_CONFIG_PATH and
PKG_CONFIG_LIBDIR so that pkg-config answers for the target. That is
right for everything built to run there and wrong for a program built to
run on the SDK host.

The kernel build compiles host tools of its own, and objtool asks
pkg-config where libelf is. It gets the target's include directory,
compiles a host tool against the target's C library headers, and stops
on warnings that -Wno-system-headers would otherwise have covered:

  usr/include/sys/cdefs.h:486: error: "__attribute_const__" redefined

Pass a pkg-config that undoes those three variables on the make command
line when the test builds an external module. It has to be a command
line assignment: the kernel assigns HOSTPKG_CONFIG with '=', so an
exported value is ignored. OE-Core already does the same thing for its
own kernel builds, in kernel.bbclass.

Fixes [YOCTO #16239].

AI-Generated: codex/claude-opus 5 (xhigh)
Signed-off-by: Trevor Woerner <twoerner@gmail.com>
---
changes in v2:
- drop the HOSTPKG_CONFIG export from the SDK environment script. It
  only ever took effect against a proposed kernel change that has since
  been abandoned, so no kernel honours it and it was dead weight. The
  make command line assignment, which is what makes the test work, is
  unchanged
- the subject loses its toolchain-scripts prefix, since that file is no
  longer touched
- drop the paragraph citing the kernel proposal
---
 meta/lib/oeqa/sdk/cases/kmod.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/meta/lib/oeqa/sdk/cases/kmod.py b/meta/lib/oeqa/sdk/cases/kmod.py
index 1be23e994fd2..1d73f076e552 100644
--- a/meta/lib/oeqa/sdk/cases/kmod.py
+++ b/meta/lib/oeqa/sdk/cases/kmod.py
@@ -26,8 +26,11 @@ class KernelModuleTest(OESDKTestCase):
         parallel_make = "-j %d" % (pmv) if pmv else ""
 
         self.ensure_target_package("kernel-devsrc")
+        # the kernel assigns HOSTPKG_CONFIG with '=', so it has to come from
+        # the make command line, as kernel.bbclass does
+        host_pkg_config = 'HOSTPKG_CONFIG="env -u PKG_CONFIG_SYSROOT_DIR -u PKG_CONFIG_PATH -u PKG_CONFIG_LIBDIR pkg-config"'
         # These targets need to be built before kernel modules can be built.
-        self._run("make %s -C $OECORE_TARGET_SYSROOT/usr/src/kernel prepare scripts" % (parallel_make))
+        self._run("make %s %s -C $OECORE_TARGET_SYSROOT/usr/src/kernel prepare scripts" % (parallel_make, host_pkg_config))
 
         with tempfile.TemporaryDirectory(prefix="cryptodev", dir=self.tc.sdk_dir) as testdir:
             git_url = "https://github.com/cryptodev-linux/cryptodev-linux"
@@ -39,5 +42,5 @@ class KernelModuleTest(OESDKTestCase):
             self.assertTrue(os.path.isdir(sourcedir))
             subprocess.check_output(["git", "-C", sourcedir, "checkout", git_sha], stderr=subprocess.STDOUT)
 
-            self._run("make -C %s V=1 KERNEL_DIR=$OECORE_TARGET_SYSROOT/usr/src/kernel" % sourcedir)
+            self._run("make -C %s V=1 %s KERNEL_DIR=$OECORE_TARGET_SYSROOT/usr/src/kernel" % (sourcedir, host_pkg_config))
             self.check_elf(os.path.join(sourcedir, "cryptodev.ko"))
-- 
2.50.0.173.g8b6f19ccfc3a