multi-kernel: fix get_kernelversion returns None for do_compileconfigs

The function get_kernelversion uses generated header files to extract the
version number. But those files are not available until do_compile, and
do_compileconfigs is injected before that, hence the version becomes None
and breaks in several places.

Introduce a new task do_preparekernel that calls "make prepare" in the
kernel tree to generate all the necessary files. It's also safer to call
do_configure early on.

Signed-off-by: Denys Dmytriyenko <denys@ti.com>

recipes-kernel/linux/linux-omap-psp_2.6.32.bb

@@ -1,5 +1,7 @@
 require multi-kernel.inc
 
+MULTI_CONFIG_BASE_SUFFIX = ""
+
 DESCRIPTION = "Linux kernel for OMAP processors"
 KERNEL_IMAGETYPE = "uImage"
 
@@ -9,7 +11,7 @@ COMPATIBLE_MACHINE = "am3517-crane|beagleboard|omap3evm|am3517-evm|dm37x-evm|am3
 SRCREV = "5fc29e7b2a76a64a739f857858ef0b98294aa155"
 
 # The main PR is now using MACHINE_KERNEL_PR, for omap3 see conf/machine/include/omap3.inc
-MACHINE_KERNEL_PR_append = "b+gitr${SRCREV}"
+MACHINE_KERNEL_PR_append = "c+gitr${SRCREV}"
 
 SRC_URI += "git://arago-project.org/git/projects/linux-omap3.git;protocol=git;branch=master \
            file://0001-Revert-omap3-beagle-Fix-compile-time-errors.patch \

recipes-kernel/linux/multi-kernel.inc

@@ -16,6 +16,14 @@ SRC_URI += " \
            file://configs "
 
 MULTI_CONFIG_BASE_SUFFIX = "multi-config-"
+MODULES_IMAGE_BASE_NAME = "modules-${PV}-${PR}-${MACHINE}"
+
+do_preparekernel () {
+	unset CFLAGS CPPFLAGS CXXFLAGS LDFLAGS MACHINE
+	oe_runmake prepare CC="${KERNEL_CC}" LD="${KERNEL_LD}"
+}
+
+addtask preparekernel after do_configure before do_compile
 
 do_compileconfigs () {
 
@@ -100,5 +108,4 @@ do_deploy_append () {
 }
 
 do_compileconfigs[depends] += "u-boot-mkimage-native:do_populate_sysroot virtual/${TARGET_PREFIX}gcc:do_populate_sysroot virtual/${TARGET_PREFIX}gcc${KERNEL_CCSUFFIX}:do_populate_sysroot"
-addtask compileconfigs after do_patch before do_configure
-
+addtask compileconfigs after do_preparekernel before do_compile