linux-backports: new package (branch yem/linux-backports)

From: Petr Vorel <[email protected]>

Backports provide drivers released on newer kernels backported for usage on older kernels.

There are two versions of linux-backports: one that supports Linux kernels >= 3.0 and one supports even older kernels. We're only packaging the version that supports >= 3.0.

linux-backports needs to have access to the kernel's .config to extract information it reintroduces as blind options in generated Kconfig snippets for its own menuconfig. However, Buildroot offers no way to express this kind of dependency.

So we need to hand-write a dependency from linux-backports' own .config to linux' .config .

Since linux.mk has not already been sourced by the time we source linux-backports.mk, we are missing the definition for LINUX_DIR, so we can not use it our rule.

Fortunately, make provides so-called "secondary expansion", by which rules which dependencies include a $$-dereferenced variable wil lbe

re-evaluated after all the rest of the Makefiles have been parsed.

So, we use that secondary expansion to post-pone evaluation of that dependency so we can use LINUX_DIR.

Note: reconstructing LINUX_DIR by hand does not work, because of the custom archives, git tree, or override-srcdir.

Signed-off-by Petr Vorel <[email protected]>

Cc Arnout Vandecappelle <[email protected]>

Cc Thomas Petazzoni <[email protected]>

Cc "Yann E. MORIN" <[email protected]>

Signed-off-by Yann E. MORIN <[email protected]>

---
Changes v8 -> v9:
- better depend on the Linux .config (Thomas)

Changes v7 -> v8: (Yann)
- fix option ordering and prompts in Config.in
- drop editors, only menuconfig is available
- add licensing information
- bump to 4.1.1-1, drop 4.0.1-1 patch
- move custom error message before call to kconfig-package
- use $(BR_BUILDING) instead of custom, wrong test on 'make source'
- drop intermediate variable to set LINUX_BACKPORTS_KCONFIG_FILE
- qstrip all variables from Config.in
- fix dependencies (tricky, needs kernel to be configured)
- check kernel is >= 3.0

Changes v6->v7:
* Bump version to lastest stable 4.0.1-1.
* Update to current version of kconfig-package.
* Add option to specify config fragments.
* Include upstream patch to fix build error.

Changes v5->v6:
Added changes by Arnout Vandecappelle in Mon Apr 20 21:46:34 UTC 2015:
* linux-backports.mk: $(LINUX_BACKPORTS_KCONFIG_FILE): linux
this doesn't help: we'd need to use:
LINUX_BACKPORTS_KCONFIG_FILE := $(LINUX_BACKPORTS_DIR)/defconfigs/$(call qstrip,$(BR2_PACKAGE_LINUX_BACKPORTS_DEFCONFIG)) but then we don't get value for $(LINUX_BACKPORTS_DIR) nor $(@D).
* linux-backports.mk: LINUX_BACKPORTS_PATCH_DEPENDENCIES = linux
This also does not help, it does linux extracting, patching, but we
need also configuring. We'd need something like
LINUX_BACKPORTS_CONFIGURE_DEPENDENCIES to be implemented.
* Config.in: info about support from kernel 3.0.
* Config.in: help text wrapped to 72 columns.

Changes v4->v5:
* Added changes made by Thomas Petazzoni in Sun, 19 Apr 2015 11:03:26 +0200.

Changes v3->v4:
* Define LINUX_BACKPORTS_MAKE_ENV instead of LINUX_BACKPORTS_MAKE_OPTS, remove TARGET_MAKE_ENV from it.
* Add nconfig to LINUX_BACKPORTS_KCONFIG_EDITORS.
* Clean formating of build commands.

---
 package/Config.in                            |  1 +
 package/linux-backports/Config.in            | 52 +++++++++++++++++
 package/linux-backports/linux-backports.hash |  2 +
 package/linux-backports/linux-backports.mk   | 87 ++++++++++++++++++++++++++++
 4 files changed, 142 insertions(+)
 create mode 100644 package/linux-backports/Config.in
 create mode 100644 package/linux-backports/linux-backports.hash
 create mode 100644 package/linux-backports/linux-backports.mk

package/Config.in +1 -0

index cfa7512..fb4df5e 100644
@@ -372,6 +372,7 @@ endif
 	source "package/kbd/Config.in"
 	source "package/lcdproc/Config.in"
 	source "package/libump/Config.in"
+	source "package/linux-backports/Config.in"
 	source "package/lirc-tools/Config.in"
 	source "package/lm-sensors/Config.in"
 	source "package/lshw/Config.in"

package/linux-backports/Config.in new file +52 -0

new file mode 100644
index 0000000..e858a45
@@ -0,0 +1,52 @@
+comment "linux-backports needs a Linux kernel to be built"
+	depends on !BR2_LINUX_KERNEL
+
+config BR2_PACKAGE_LINUX_BACKPORTS
+	bool "linux-backports"
+	depends on BR2_LINUX_KERNEL
+	help
+	  The linux-backports package includes many Linux drivers from
+	  recent kernels, backported to older ones.
+
+	  This version of linux-backports supports kernels starting from 3.0.
+
+	  https://backports.wiki.kernel.org
+
+if BR2_PACKAGE_LINUX_BACKPORTS
+
+choice
+	prompt "Linux kernel driver backports configuration"
+	default BR2_PACKAGE_LINUX_BACKPORTS_USE_DEFCONFIG
+
+config BR2_PACKAGE_LINUX_BACKPORTS_USE_DEFCONFIG
+	bool "Using an in-tree defconfig file"
+
+config BR2_PACKAGE_LINUX_BACKPORTS_USE_CUSTOM_CONFIG
+	bool "Using a custom (def)config file"
+
+endchoice
+
+config BR2_PACKAGE_LINUX_BACKPORTS_DEFCONFIG
+	string "Defconfig name"
+	depends on BR2_PACKAGE_LINUX_BACKPORTS_USE_DEFCONFIG
+	help
+	  Name of the backports defconfig file to use, without the
+	  leading defconfig-. The defconfig is located in defconfigs/
+	  directory in the backports tree.
+
+config BR2_PACKAGE_LINUX_BACKPORTS_CUSTOM_CONFIG_FILE
+	string "Configuration file path"
+	depends on BR2_PACKAGE_LINUX_BACKPORTS_USE_CUSTOM_CONFIG
+	help
+	  Path to the backports configuration file
+
+	  Note: this can be a defconfig file or a complete .config file,
+	  which can later be saved back with make linux-update-(def)config.
+
+config BR2_PACKAGE_LINUX_BACKPORTS_CONFIG_FRAGMENT_FILES
+	string "Additional configuration fragment files"
+	help
+	  A space-separated list of configuration fragment files, that
+	  will be merged to the main linux-backports configuration file.
+
+endif # BR2_PACKAGE_LINUX_BACKPORTS

package/linux-backports/linux-backports.hash new file +2 -0

new file mode 100644
index 0000000..0d41067
@@ -0,0 +1,2 @@
+# From: https://www.kernel.org/pub/linux/kernel/projects/backports/stable/v4.1.1/sha256sums.asc
+sha256 7fca160665b801796ce50def18f2fd6def1c4452290e93ec5332444fb2021bd6  backports-4.1.1-1.tar.xz

package/linux-backports/linux-backports.mk new file +87 -0

new file mode 100644
index 0000000..e4ac9f4
@@ -0,0 +1,87 @@
+################################################################################
+#
+# linux-backports
+#
+################################################################################
+
+LINUX_BACKPORTS_VERSION_MAJOR = 4.1.1
+LINUX_BACKPORTS_VERSION = $(LINUX_BACKPORTS_VERSION_MAJOR)-1
+LINUX_BACKPORTS_SOURCE = backports-$(LINUX_BACKPORTS_VERSION).tar.xz
+LINUX_BACKPORTS_SITE = $(BR2_KERNEL_MIRROR)/linux/kernel/projects/backports/stable/v$(LINUX_BACKPORTS_VERSION_MAJOR)
+LINUX_BACKPORTS_LICENSE = GPLv2
+LINUX_BACKPORTS_LICENSE_FILES = COPYING
+
+LINUX_BACKPORTS_DEPENDENCIES = linux
+
+LINUX_BACKPORTS_MAKE_OPTS = \
+	$(LINUX_MAKE_FLAGS) \
+	KLIB_BUILD=$(LINUX_DIR) \
+	KLIB=$(TARGET_DIR)
+
+ifeq ($(BR2_PACKAGE_LINUX_BACKPORTS_USE_DEFCONFIG),y)
+LINUX_BACKPORTS_KCONFIG_FILE = $(LINUX_BACKPORTS_DIR)/defconfigs/$(call qstrip,$(BR2_PACKAGE_LINUX_BACKPORTS_DEFCONFIG))
+else ifeq ($(BR2_PACKAGE_LINUX_BACKPORTS_USE_CUSTOM_CONFIG),y)
+LINUX_BACKPORTS_KCONFIG_FILE = $(call qstrip,$(BR2_PACKAGE_LINUX_BACKPORTS_CUSTOM_CONFIG_FILE))
+endif
+
+define LINUX_BACKPORTS_BUILD_CMDS
+	$(TARGET_MAKE_ENV) $(MAKE) $(LINUX_BACKPORTS_MAKE_OPTS) -C $(@D)
+endef
+
+define LINUX_BACKPORTS_INSTALL_TARGET_CMDS
+	$(TARGET_MAKE_ENV) $(MAKE) $(LINUX_BACKPORTS_MAKE_OPTS) \
+		-C $(LINUX_DIR) M=$(@D) \
+		INSTALL_MOD_DIR=backports \
+		modules_install
+endef
+
+LINUX_BACKPORTS_KCONFIG_FRAGMENT_FILES = $(call qstrip,$(BR2_PACKAGE_LINUX_BACKPORTS_CONFIG_FRAGMENT_FILES))
+LINUX_BACKPORTS_KCONFIG_OPTS = $(LINUX_BACKPORTS_MAKE_OPTS)
+
+# Checks to give errors that the user can understand
+ifeq ($(BR_BUILDING),y)
+
+ifeq ($(BR2_PACKAGE_LINUX_BACKPORTS_USE_DEFCONFIG),y)
+ifeq ($(call qstrip,$(BR2_PACKAGE_LINUX_BACKPORTS_DEFCONFIG)),)
+$(error No linux-backports defconfig name specified, check your BR2_PACKAGE_LINUX_BACKPORTS_DEFCONFIG setting)
+endif
+endif
+
+ifeq ($(BR2_PACKAGE_LINUX_BACKPORTS_USE_CUSTOM_CONFIG),y)
+ifeq ($(call qstrip,$(BR2_PACKAGE_LINUX_BACKPORTS_CUSTOM_CONFIG_FILE)),)
+$(error No linux-backports configuration file specified, check your BR2_PACKAGE_LINUX_BACKPORTS_CUSTOM_CONFIG_FILE setting)
+endif
+endif
+
+endif # BR_BUILDING
+
+$(eval $(kconfig-package))
+
+# linux-backports' own .config file needs options from the kernel's own
+# .config file. The dependencies handling in the infrastructure does not
+# allow to express this kind of dependencies. Besides, linux.mk might
+# not have been parsed yet, so the Linux build dir LINUX_DIR is not yet
+# known. Thus, we use a "secondary expansion" so the rule is re-evaluated
+# after all Makefiles are parsed, and thus at that time we will have the
+# LINUX_DIR variable set to the proper value.
+#
+# Furthermore, we want to check the kernel version, since linux-backports
+# only supports kernels >= 3.0. To avoid overriding linux-backports'
+# .config rule defined in the kconfig-package infra, we use an
+# intermediate stamp-file.
+#
+# Finally, it must also come after the call to kconfig-package, so we get
+# LINUX_BACKPORTS_DIR properly defined (because the target part of the
+# rule is not re-evaluated).
+#
+$(LINUX_BACKPORTS_DIR)/.config: $(LINUX_BACKPORTS_DIR)/.stamp_check_kernel_version
+
+.SECONDEXPANSION:
+$(LINUX_BACKPORTS_DIR)/.stamp_check_kernel_version: $$(LINUX_DIR)/.config
+	$(Q)LINUX_VERSION_PROBED=$(LINUX_VERSION_PROBED); \
+	if [ $${LINUX_VERSION_PROBED%%.*} -lt 3 ]; then \
+		printf "Linux version '%s' is too old for linux-backports (needs 3.0 or later)\n" \
+			"$${LINUX_VERSION_PROBED}"; \
+		exit 1; \
+	fi
+	$(Q)touch $(@)

linux-backports manually generates its autoconf.h header, which needs a .config file.

Using a pre- or post-configure hook does not really work, because generating that file touches the .config, and thus our .stamp files ar enot longer properly time-ordered and running a subsequent make would incorrectly believe it has to rebuild linux-backports.

So, even though this is not a fixup proper, we generate that file from the _KCONFIG_FIXUP_CMDS to ensure the stampt file is created after we touch .config.

Signed-off-by "Yann E. MORIN" <[email protected]>

Cc Petr Vorel <[email protected]>

Cc Thomas Petazzoni <[email protected]>

---
Changes v8 -> v9:
- comment tricky constructs (Thomas)
- use _KCONFIG_FIXUP_CMDS instead of POST_CONFIGURE_HOOKS

---
 package/linux-backports/linux-backports.mk | 48 +++++++++++++++++++-----------
 1 file changed, 30 insertions(+), 18 deletions(-)

package/linux-backports/linux-backports.mk +8 -18

index e4ac9f4..44ac7e7 100644
@@ -11,33 +11,44 @@ LINUX_BACKPORTS_SITE = $(BR2_KERNEL_MIRROR)/linux/kernel/projects/backports/stab
 LINUX_BACKPORTS_LICENSE = GPLv2
 LINUX_BACKPORTS_LICENSE_FILES = COPYING
 
-LINUX_BACKPORTS_DEPENDENCIES = linux
-
-LINUX_BACKPORTS_MAKE_OPTS = \
-	$(LINUX_MAKE_FLAGS) \
-	KLIB_BUILD=$(LINUX_DIR) \
-	KLIB=$(TARGET_DIR)
-
 ifeq ($(BR2_PACKAGE_LINUX_BACKPORTS_USE_DEFCONFIG),y)
 LINUX_BACKPORTS_KCONFIG_FILE = $(LINUX_BACKPORTS_DIR)/defconfigs/$(call qstrip,$(BR2_PACKAGE_LINUX_BACKPORTS_DEFCONFIG))
 else ifeq ($(BR2_PACKAGE_LINUX_BACKPORTS_USE_CUSTOM_CONFIG),y)
 LINUX_BACKPORTS_KCONFIG_FILE = $(call qstrip,$(BR2_PACKAGE_LINUX_BACKPORTS_CUSTOM_CONFIG_FILE))
 endif
 
-define LINUX_BACKPORTS_BUILD_CMDS
-	$(TARGET_MAKE_ENV) $(MAKE) $(LINUX_BACKPORTS_MAKE_OPTS) -C $(@D)
-endef
-
-define LINUX_BACKPORTS_INSTALL_TARGET_CMDS
-	$(TARGET_MAKE_ENV) $(MAKE) $(LINUX_BACKPORTS_MAKE_OPTS) \
-		-C $(LINUX_DIR) M=$(@D) \
-		INSTALL_MOD_DIR=backports \
-		modules_install
-endef
-
 LINUX_BACKPORTS_KCONFIG_FRAGMENT_FILES = $(call qstrip,$(BR2_PACKAGE_LINUX_BACKPORTS_CONFIG_FRAGMENT_FILES))
 LINUX_BACKPORTS_KCONFIG_OPTS = $(LINUX_BACKPORTS_MAKE_OPTS)
 
+# linux-backports' build system expects the config options to be present
+# in the environment, and it is so when using their custom buildsystem,
+# because they are set in the main Makefile, which then calls a second
+# Makefile.
+#
+# In our case, we do not use that first Makefile. So, we parse the
+# .config file, filter-out comment lines and put the rest as command
+# line variables.

package/linux-backports/linux-backports.mk +12 -0

+
+LINUX_BACKPORTS_MODULE_MAKE_OPTS = $(LINUX_BACKPORTS_MAKE_OPTS)
+
+# This file is not automatically generated by 'oldconfig' that we use in
+# the kconfig-package infrastructure. In the linux buildsystem, it is
+# generated by running silentoldconfig, but that's not the case for
+# linux-backports: it uses a hand-crafted rule to generate that file.
+define LINUX_BACKPORTS_KCONFIG_FIXUP_CMDS
+	$(MAKE) -C $(@D) $(LINUX_BACKPORTS_MAKE_OPTS) backport-include/backport/autoconf.h
+endef
+
 # Checks to give errors that the user can understand
 ifeq ($(BR_BUILDING),y)
 

@@ -55,6 +66,7 @@ endif
 
 endif # BR_BUILDING
 
+$(eval $(kernel-module))
 $(eval $(kconfig-package))
 
 # linux-backports' own .config file needs options from the kernel's own

Petr Vorel (1):
package/linux-backports: new package

Yann E. MORIN (1):
package/linux-backports: switch to using the kernel-module infra