Commit 63abfb72 authored by Yann E. MORIN's avatar Yann E. MORIN Committed by Peter Korsgaard
Browse files

package/linux-headers: add option to use same sources as the kernel 



Some heavily (and most often improperly) modified Linux kernels may export
new APIs to userland, so as to speak to custom hardware or custom kernel
facilities.

However, we currently have no easy way to use such kernels as a source
for the linux-headers package, which precludes having those userland
headers intalled for userland applications to use them.

We do have a way for the kernel to use the same version as for the
headers, but that is definitely not enough, as the linux-headers package
has a version choice that is far less versatile and capable than that of
the linux package.

Add a new option for the linux-headers package, for the user to specify
that the version (really, the sources) of the kernel be used to install
the headers from.

We do that by making linux-headers patch-depend on the linux package.

We can't have linux-header simply depend on linux, because the simple
dependency means the the dependee will be configured, built and installed
before the dependent is configured. And since linux is a target package,
it depends on the toolchain, which internally dependes on linux-headers,
which would depend on linux, and we'd get a circular dependency.

Using patch-depend will ensure that linux is extracted and patched
before linux-headers is extracted, which is really all we need.

Then, we install the headers from the linux source tree, rather than
from linux-headers' source tree (as there's nothing in there!).

Since we need to install a private set for uClibc (see cde947f5, uclibc:
prevent rebuilding after installation to staging), we explicitly set
INSTALL_HDR_PATH when calling the kernel' install-headers rule in
LINUX_HEADERS_CONFIGURE_CMDS, so that the headers are installed in
linux-headers' $(@D) instead of linux' $(@D).

Finally, as there is no way to know the kernel version in this case, we
must still prompt the user for the kernel series the headers are from
(like we do for a custom version) and check for consistency at build
time.

Note however that this still leaves users that want to built their
such-kernel outside of Buildroot out in the cold.

[Peter: drop comment as suggested by Thomas]
Signed-off-by: default avatar"Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Karoly Kasza <kaszak@gmail.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Peter Korsgaard <jacmet@uclibc.org>
Signed-off-by: default avatarPeter Korsgaard <peter@korsgaard.com>
parent c823c6ee

linux/Config.in

+1 −0
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ config BR2_LINUX_KERNEL_LATEST_VERSION 


config BR2_LINUX_KERNEL_SAME_AS_HEADERS

	bool "Same as toolchain kernel headers"

	depends on !BR2_KERNEL_HEADERS_AS_KERNEL

	depends on BR2_TOOLCHAIN_BUILDROOT

	help

	  This option will re-use the same kernel sources as the one

package/linux-headers/Config.in.host

+6 −1
Original line number Diff line number Diff line
@@ -5,12 +5,17 @@ comment "Kernel Header Options" 


choice

	prompt "Kernel Headers"

	default BR2_KERNEL_HEADERS_AS_KERNEL if BR2_LINUX_KERNEL

	default BR2_KERNEL_HEADERS_4_4

	help

	  Select the version of kernel header files you wish to use.

	  You must select the correct set of header files to match

	  the kernel you intend to use on your target system.



	config BR2_KERNEL_HEADERS_AS_KERNEL

		bool "Same as kernel"

		depends on BR2_LINUX_KERNEL



	config BR2_KERNEL_HEADERS_3_2

		bool "Linux 3.2.x kernel headers"

		depends on !BR2_arc && !BR2_nios2
@@ -87,7 +92,7 @@ config BR2_DEFAULT_KERNEL_VERSION 


choice

	bool "Custom kernel headers series"

	depends on BR2_KERNEL_HEADERS_VERSION

	depends on BR2_KERNEL_HEADERS_VERSION || BR2_KERNEL_HEADERS_AS_KERNEL

	default BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_REALLY_OLD

	help

	  Set to the kernel headers series you manually set above.

package/linux-headers/linux-headers.mk

+22 −3
Original line number Diff line number Diff line
@@ -7,6 +7,19 @@ 
# This package is used to provide Linux kernel headers for the

# internal toolchain backend.



ifeq ($(BR2_KERNEL_HEADERS_AS_KERNEL),y)



LINUX_HEADERS_VERSION = none

LINUX_HEADERS_SOURCE =



LINUX_HEADERS_LICENSE = $(LINUX_LICENSE)

LINUX_HEADERS_LICENSE_FILES = $(LINUX_LICENSE_FILES)



LINUX_HEADERS_PATCH_DEPENDENCIES = linux

LINUX_HEADERS_REAL_DIR = $(LINUX_DIR)



else # ! BR2_KERNEL_HEADERS_AS_KERNEL



LINUX_HEADERS_VERSION = $(call qstrip,$(BR2_DEFAULT_KERNEL_HEADERS))

ifeq ($(findstring x2.6.,x$(LINUX_HEADERS_VERSION)),x2.6.)

LINUX_HEADERS_SITE = $(BR2_KERNEL_MIRROR)/linux/kernel/v2.6
@@ -16,9 +29,14 @@ else ifeq ($(findstring x4.,x$(LINUX_HEADERS_VERSION)),x4.) 
LINUX_HEADERS_SITE = $(BR2_KERNEL_MIRROR)/linux/kernel/v4.x

endif

LINUX_HEADERS_SOURCE = linux-$(LINUX_HEADERS_VERSION).tar.xz



LINUX_HEADERS_LICENSE = GPLv2

LINUX_HEADERS_LICENSE_FILES = COPYING



LINUX_HEADERS_REAL_DIR = $(@D)



endif # ! BR2_KERNEL_HEADERS_AS_KERNEL



LINUX_HEADERS_INSTALL_STAGING = YES



# linux-headers is part of the toolchain so disable the toolchain dependency
@@ -35,17 +53,18 @@ LINUX_HEADERS_ADD_TOOLCHAIN_DEPENDENCY = NO 
# uClibc building. This way uClibc doesn't modify linux headers on installation

# of "its" headers

define LINUX_HEADERS_CONFIGURE_CMDS

	(cd $(@D); \

	(cd $(LINUX_HEADERS_REAL_DIR); \

		$(TARGET_MAKE_ENV) $(MAKE) \

			ARCH=$(KERNEL_ARCH) \

			HOSTCC="$(HOSTCC)" \

			HOSTCFLAGS="$(HOSTCFLAGS)" \

			HOSTCXX="$(HOSTCXX)" \

			INSTALL_HDR_PATH=$(@D)/usr \

			headers_install)

endef



define LINUX_HEADERS_INSTALL_STAGING_CMDS

	(cd $(@D); \

	(cd $(LINUX_HEADERS_REAL_DIR); \

		$(TARGET_MAKE_ENV) $(MAKE) \

			ARCH=$(KERNEL_ARCH) \

			HOSTCC="$(HOSTCC)" \
@@ -55,7 +74,7 @@ define LINUX_HEADERS_INSTALL_STAGING_CMDS 
			headers_install)

endef



ifeq ($(BR2_KERNEL_HEADERS_VERSION),y)

ifeq ($(BR2_KERNEL_HEADERS_VERSION)$(BR2_KERNEL_HEADERS_AS_KERNEL),y)

define LINUX_HEADERS_CHECK_VERSION

	$(call check_kernel_headers_version,\

		$(STAGING_DIR),\