[PATCH v2] Explicitly mapping between i386/x86_64 and x86 for kernel ARCH

[Jianxun Zhang <jianxun.zhang@linux.intel.com>]

For a bare-bone kernel recipe which specifies 32 bit x86 target,
a 64 bit .config will be generated from do_configure task when
building 32-bit qemux86, once all of these conditions are true:

() arch of host is x86_64
() kernel source tree used in build has commit ffee0de41 which
actually chooses i386 or x86_64 defconfig by asking host when
ARCH is "x86" (arch/x86/Makefile)
() bare-bone kernel recipe inherits directly from kernel without
other special treatments.

Build will fail because of the mismatched kernel architecture.

The patch sets ARCH i386 or x86_64 explicitly to configure
task to avoid this host contamination. Kernel artifact is also
changed so that it can map i386 and x64 back to arch/x86 when
needed.

Signed-off-by: Jianxun Zhang <jianxun.zhang@linux.intel.com>
---

The old V1 broke lttng-modules building in the last submission. This V2 updates
kernel artifact to fix it. Considering there are multiple references of ARCH
in poky, a better test coverage is suggested before merging it to mainline, even
I have done some build tests prior to submission.

 meta/classes/kernel-arch.bbclass |  4 +++-
 meta/classes/kernel.bbclass      | 15 ++++++++++++---
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/meta/classes/kernel-arch.bbclass b/meta/classes/kernel-arch.bbclass
index 3ed5986..d8b180e 100644
--- a/meta/classes/kernel-arch.bbclass
+++ b/meta/classes/kernel-arch.bbclass
@@ -21,7 +21,9 @@ def map_kernel_arch(a, d):
 
     valid_archs = d.getVar('valid_archs', True).split()
 
-    if   re.match('(i.86|athlon|x86.64)$', a):  return 'x86'
+    if   re.match('i.86$', a):                  return 'i386'
+    elif re.match('x86.64$', a):                return 'x86_64'
+    elif re.match('athlon$', a):                return 'x86'
     elif re.match('armeb$', a):                 return 'arm'
     elif re.match('aarch64$', a):               return 'arm64'
     elif re.match('aarch64_be$', a):            return 'arm64'
diff --git a/meta/classes/kernel.bbclass b/meta/classes/kernel.bbclass
index 997376d..5c3287b 100644
--- a/meta/classes/kernel.bbclass
+++ b/meta/classes/kernel.bbclass
@@ -317,9 +317,18 @@ do_shared_workdir () {
 		cp -fR include/generated/* $kerneldir/include/generated/
 	fi
 
-	if [ -d arch/${ARCH}/include/generated ]; then
-		mkdir -p $kerneldir/arch/${ARCH}/include/generated/
-		cp -fR arch/${ARCH}/include/generated/* $kerneldir/arch/${ARCH}/include/generated/
+	# When ARCH is set to i386 or x86_64, we need to map ARCH to the real name of src
+	# dir (x86) under arch/ of kenrel tree, so that we can find correct source to copy.
+
+	if [ "${ARCH}" = "i386" ] || [ "${ARCH}" = "x86_64" ]; then
+		KERNEL_SRCARCH=x86
+	else
+		KERNEL_SRCARCH=${ARCH}
+	fi
+
+	if [ -d arch/${KERNEL_SRCARCH}/include/generated ]; then
+		mkdir -p $kerneldir/arch/${KERNEL_SRCARCH}/include/generated/
+		cp -fR arch/${KERNEL_SRCARCH}/include/generated/* $kerneldir/arch/${KERNEL_SRCARCH}/include/generated/
 	fi
 }
 
-- 
1.9.1