[PATCH v4 2/3] linux-custom: Provide host and target specific kernel kbuild packages

[Stefan Koch <stefan-koch@siemens.com>]

When using a cross build this patch does introduce optionally
host and target specific kernel kbuild packages that
ship the "scripts" and "tools" binaries.

By default at cross builds a kbuild-cross package will be
generated that provides the host specific kbuild package.

The "-compat" and "-native" multiarch bitbake targets are useable to run
additional target or host specific builds for kbuild scripts and tools.

Using the "-compat" bitbake target enables the build of
a target specific kbuild package at cross builds.

Using the "-native" bitbake target enables the build of
a host specific kbuild package at cross builds.

This solves this from doc/custom_kernel.inc:
- The kernel headers package has not supported both native
  and cross compilation of kernel modules when itself was cross built
- Future roadmap: Generate kernel headers package for both host
  and target when using a cross build

Signed-off-by: Stefan Koch <stefan-koch@siemens.com>
---
 .../linux/files/debian/control.tmpl           | 16 +++++-
 .../linux/files/debian/isar/build.tmpl        | 12 ++++-
 .../linux/files/debian/isar/common.tmpl       |  8 +++
 .../linux/files/debian/isar/install.tmpl      | 26 ++++++----
 .../linux/files/debian/rules.tmpl             |  2 +-
 meta/recipes-kernel/linux/linux-custom.inc    | 49 ++++++++++++++++---
 6 files changed, 94 insertions(+), 19 deletions(-)

diff --git a/meta/recipes-kernel/linux/files/debian/control.tmpl b/meta/recipes-kernel/linux/files/debian/control.tmpl
index b19ca2c9..c012048b 100644
--- a/meta/recipes-kernel/linux/files/debian/control.tmpl
+++ b/meta/recipes-kernel/linux/files/debian/control.tmpl
@@ -6,6 +6,7 @@ Build-Depends: bc, kmod, cpio, ${KBUILD_DEPENDS}
 Homepage: http://www.kernel.org/
 
 Package: linux-image-${KERNEL_NAME_PROVIDED}
+Build-Profiles: <!targetbuild !hostbuild>
 Architecture: any
 Depends: ${KERNEL_DEBIAN_DEPENDS}
 Description: ${KERNEL_NAME_PROVIDED} Linux kernel, version @KR@
@@ -13,6 +14,7 @@ Description: ${KERNEL_NAME_PROVIDED} Linux kernel, version @KR@
  files, version: @KR@.
 
 Package: linux-headers-${KERNEL_NAME_PROVIDED}
+Build-Profiles: <!targetbuild !hostbuild>
 Architecture: any
 Depends: ${KERNEL_HEADERS_DEBIAN_DEPENDS}, ${perl:Depends}, ${shlib:Depends}
 Description: ${KERNEL_NAME_PROVIDED} Linux kernel headers for @KR@
@@ -21,7 +23,7 @@ Description: ${KERNEL_NAME_PROVIDED} Linux kernel headers for @KR@
  This is useful for people who need to build external modules
 
 Package: linux-libc-dev
-Build-Profiles: <!nolibcdev>
+Build-Profiles: <!nolibcdev !targetbuild !hostbuild>
 Section: devel
 Provides: linux-kernel-headers
 Architecture: any
@@ -30,6 +32,7 @@ Description: Linux support headers for userspace development
  are used by the installed headers for GNU glibc and other system libraries.
 
 Package: linux-image-${KERNEL_NAME_PROVIDED}-dbg
+Build-Profiles: <!targetbuild !hostbuild>
 Section: debug
 Architecture: any
 Description: Linux kernel debugging symbols for @KR@
@@ -37,8 +40,19 @@ Description: Linux kernel debugging symbols for @KR@
  all the necessary debug symbols for the kernel and its modules.
 
 Package: linux-kbuild-${KERNEL_NAME_PROVIDED}
+Build-Profiles: <targetbuild> <hostbuild> <defaultkbuild>
 Architecture: any
 Depends: ${perl:Depends}, ${shlib:Depends}
 Description: ${KERNEL_NAME_PROVIDED} Linux kbuild scripts and tools for @KR@
  This package provides kernel kbuild scripts and tools for @KR@
  This is useful for people who need to build external modules
+
+Package: linux-kbuild-${KERNEL_NAME_PROVIDED}-cross
+Build-Profiles: <!targetbuild !hostbuild crosskbuild>
+Architecture: any
+Depends: ${KERNEL_HEADERS_DEBIAN_DEPENDS}, ${perl:Depends}, ${shlib:Depends}
+Description: ${KERNEL_NAME_PROVIDED} Linux kbuild scripts and tools for @KR@
+ This package provides kernel kbuild scripts and tools
+ as ${HOST_ARCH} cross binaries for @KR@
+ This is useful for those who need to cross build
+ external modules using ISAR's sbuild-chroot-host
diff --git a/meta/recipes-kernel/linux/files/debian/isar/build.tmpl b/meta/recipes-kernel/linux/files/debian/isar/build.tmpl
index 906dc580..7f293528 100644
--- a/meta/recipes-kernel/linux/files/debian/isar/build.tmpl
+++ b/meta/recipes-kernel/linux/files/debian/isar/build.tmpl
@@ -22,7 +22,17 @@ do_build() {
     sed -i "s/@KR@/${KR}/g" ${S}/debian/control ${S}/debian/linux-image-${KERNEL_NAME_PROVIDED}.*
 
     # Build the Linux kernel
-    ${MAKE} O=${KERNEL_BUILD_DIR} ${PARALLEL_MAKE} KCFLAGS="${KCFLAGS}" KAFLAGS="${KAFLAGS}"
+    if echo "${DEB_BUILD_PROFILES}" | grep -q -e "targetbuild" -e "hostbuild"; then # Build kernel scripts and tools
+        ${MAKE} O=${KERNEL_BUILD_DIR} ${PARALLEL_MAKE} KCFLAGS="${KCFLAGS}" KAFLAGS="${KAFLAGS}" scripts
+        if grep -q -E "CONFIG_STACK_VALIDATION=y|CONFIG_HAVE_OBJTOOL=y" ${KERNEL_BUILD_DIR}/.config && [ -d "tools/objtool" ]; then
+            ${MAKE} O=${KERNEL_BUILD_DIR} ${PARALLEL_MAKE} KCFLAGS="${KCFLAGS}" KAFLAGS="${KAFLAGS}" tools/objtool || true
+        fi
+        if grep -q "CONFIG_MODULES=y" ${KERNEL_BUILD_DIR}/.config; then
+            ${MAKE} O=${KERNEL_BUILD_DIR} ${PARALLEL_MAKE} KCFLAGS="${KCFLAGS}" KAFLAGS="${KAFLAGS}" modules_prepare
+        fi
+    else # Build the Linux kernel
+        ${MAKE} O=${KERNEL_BUILD_DIR} ${PARALLEL_MAKE} KCFLAGS="${KCFLAGS}" KAFLAGS="${KAFLAGS}"
+    fi
 
     # Stop tracing
     set +x
diff --git a/meta/recipes-kernel/linux/files/debian/isar/common.tmpl b/meta/recipes-kernel/linux/files/debian/isar/common.tmpl
index f4c0519f..36e01691 100644
--- a/meta/recipes-kernel/linux/files/debian/isar/common.tmpl
+++ b/meta/recipes-kernel/linux/files/debian/isar/common.tmpl
@@ -11,6 +11,14 @@ KERNEL_PKG_KERN_HEADERS=linux-headers-${KERNEL_NAME_PROVIDED}
 KERNEL_PKG_LIBC_HEADERS=linux-libc-dev
 KERNEL_PKG_KERN_KBUILD=linux-kbuild-${KERNEL_NAME_PROVIDED}
 
+if echo "${DEB_BUILD_PROFILES}" | grep -q "hostbuild"; then
+	# Force creating kernel kbuild debian package with valid host arch
+	# Use a cross build to comply with arch specific kernel defconfigs
+	# The scripts and tools are always created for host arch
+	eval $(dpkg-architecture -f -A ${DISTRO_ARCH})
+	CROSS_COMPILE=${DEB_TARGET_GNU_TYPE}-
+fi
+
 # Constants
 KCONF=.config
 
diff --git a/meta/recipes-kernel/linux/files/debian/isar/install.tmpl b/meta/recipes-kernel/linux/files/debian/isar/install.tmpl
index 236b67c4..08b8a9a5 100644
--- a/meta/recipes-kernel/linux/files/debian/isar/install.tmpl
+++ b/meta/recipes-kernel/linux/files/debian/isar/install.tmpl
@@ -34,18 +34,24 @@ do_install() {
     set -x
 
     # Run the install steps
-    install_image
-    if [ "${ARCH}" != "um" ]; then
-        install_config
-        install_map
+    if ! echo "${DEB_BUILD_PROFILES}" | grep -q -e "targetbuild" -e "hostbuild"; then
+        install_image
+        if [ "${ARCH}" != "um" ]; then
+            install_config
+            install_map
+        fi
+        install_hooks
+        install_dtbs
+        install_kmods
+        install_headers
     fi
-    install_hooks
-    install_dtbs
-    install_kmods
-    install_headers
 
-    # Cleanup and install kernel scripts and tools
-    rm -rf ${deb_kern_kbuild_dir}
+    if ! echo "${DEB_BUILD_PROFILES}" | grep -q -e "targetbuild" -e "hostbuild" && echo "${DEB_BUILD_PROFILES}" | grep -q "crosskbuild"; then
+        # Install cross kernel scripts and tools
+        install_kbuild ${deb_kern_kbuild_dir}-cross
+    fi
+
+    # Install kernel scripts and tools
     install_kbuild ${deb_kern_kbuild_dir}
 
     # Stop tracing
diff --git a/meta/recipes-kernel/linux/files/debian/rules.tmpl b/meta/recipes-kernel/linux/files/debian/rules.tmpl
index e8ae3daa..1f838a41 100755
--- a/meta/recipes-kernel/linux/files/debian/rules.tmpl
+++ b/meta/recipes-kernel/linux/files/debian/rules.tmpl
@@ -48,4 +48,4 @@ override_dh_strip_nondeterminism:
 	true
 
 override_dh_strip:
-	unset DEB_HOST_GNU_TYPE && dh_strip -Xvmlinu --no-automatic-dbgsym
+	dh_strip -Xvmlinu -Xlinux-kbuild-${KERNEL_NAME_PROVIDED}-cross --no-automatic-dbgsym
diff --git a/meta/recipes-kernel/linux/linux-custom.inc b/meta/recipes-kernel/linux/linux-custom.inc
index 94ed84a2..85faa2d7 100644
--- a/meta/recipes-kernel/linux/linux-custom.inc
+++ b/meta/recipes-kernel/linux/linux-custom.inc
@@ -85,9 +85,6 @@ TEMPLATE_VARS += "                \
     DISTRIBUTOR                   \
 "
 
-inherit dpkg
-inherit template
-
 # Add custom cflags to the kernel build
 KCFLAGS ?= "-fdebug-prefix-map=${CURDIR}=."
 KAFLAGS ?= "-fdebug-prefix-map=${CURDIR}=."
@@ -95,17 +92,57 @@ KAFLAGS ?= "-fdebug-prefix-map=${CURDIR}=."
 # Derive name of the kernel packages from the name of this recipe
 KERNEL_NAME_PROVIDED ?= "${@ d.getVar('PN').partition('linux-')[2]}"
 
-# Make bitbake know we will be producing linux-image and linux-headers packages
 python() {
     kernel_name = d.getVar("KERNEL_NAME_PROVIDED")
-    d.setVar('PROVIDES', 'linux-image-' + kernel_name + ' ' + \
-                         'linux-headers-' + kernel_name)
+    distro_arch = d.getVar("DISTRO_ARCH")
+    host_arch = d.getVar("HOST_ARCH")
     headers_depends = "linux-kbuild-" + kernel_name
 
+    # The "-compat" and "-native" multiarch bitbake targets are used to run
+    # additional target or host specific builds for kbuild scripts and tools.
+    # The "-compat" bitbake target requests a "target" build
+    # and the "-native" bitbake target requests a "host" build.
+    #
+    # For different distro and host archs
+    # - Add dependency for sbuild-chroot-target
+    #   to allow building arch specific kbuild scripts and tools
+    # - Set correct variable overrides
+    is_compat = "compat" in d.getVar("PN", True)
+    is_native = "native" in d.getVar("PN", True)
+
+    # Determine creation of a kbuild-cross or (standard) kbuild package for the host
+    is_cross_profile = distro_arch != host_arch and d.getVar("ISAR_CROSS_COMPILE", True) == "1"
+
+    if is_cross_profile:
+        headers_depends = headers_depends + "-cross | " + headers_depends
+        build_depends = "crossbuild-essential-" + distro_arch + " [" + host_arch + "], "
+        d.appendVar("DEB_BUILD_PROFILES", " crosskbuild")
+        d.prependVar("KBUILD_DEPENDS", build_depends)
+        d.appendVarFlag("do_prepare_build", "depends", " sbuild-chroot-target:do_build")
+        d.setVar("ISAR_ENABLE_COMPAT_ARCH", "1")
+        d.setVar("COMPAT_DISTRO_ARCH", distro_arch)
+
+        if is_compat:
+            d.appendVar("DEB_BUILD_PROFILES", " targetbuild")
+            d.setVar("ISAR_CROSS_COMPILE", "0")
+        elif is_native:
+            d.appendVar("DEB_BUILD_PROFILES", " hostbuild")
+    else:
+        d.appendVar("DEB_BUILD_PROFILES", " defaultkbuild")
+
+    # Make bitbake know we will be producing
+    # linux-image and linux-headers packages
+    if not is_compat and not is_native:
+        d.setVar("PROVIDES", "linux-image-" + kernel_name + " " + \
+                             "linux-headers-" + kernel_name)
+
     # Set dependency for kernel headers
     d.appendVar("KERNEL_HEADERS_DEBIAN_DEPENDS", headers_depends)
 }
 
+inherit dpkg
+inherit template
+
 def get_kernel_arch(d):
     distro_arch = d.getVar("DISTRO_ARCH")
     if distro_arch in ["amd64", "i386"]:
-- 
2.39.2