kbuild: use INSTALLKERNEL to select customized installkernel script

Replace the use of CROSS_COMPILE to select a customized
installkernel script with the possibility to set INSTALLKERNEL
to select a custom installkernel script when running make:

    make INSTALLKERNEL=arm-installkernel install

With this patch we are now more consistent across
different architectures - they did not all support use
of CROSS_COMPILE.

The use of CROSS_COMPILE was a hack as this really belongs
to gcc/binutils and the installkernel script does not change
just because we change toolchain.

The use of CROSS_COMPILE caused troubles with an upcoming patch
that saves CROSS_COMPILE when a kernel is built - it would no
longer be installable.
[Thanks to Peter Z. for this hint]

This patch undos what Ian did in commit:

  0f8e2d62fa04441cd12c08ce521e84e5bd3f8a46
  ("use ${CROSS_COMPILE}installkernel in arch/*/boot/install.sh")

The patch has been lightly tested on x86 only - but all changes
looks obvious.

Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Mike Frysinger <vapier@gentoo.org> [blackfin]
Acked-by: Russell King <linux@arm.linux.org.uk> [arm]
Acked-by: Paul Mundt <lethal@linux-sh.org> [sh]
Acked-by: "H. Peter Anvin" <hpa@zytor.com> [x86]
Cc: Ian Campbell <icampbell@arcom.com>
Cc: Tony Luck <tony.luck@intel.com> [ia64]
Cc: Fenghua Yu <fenghua.yu@intel.com> [ia64]
Cc: Hirokazu Takata <takata@linux-m32r.org> [m32r]
Cc: Geert Uytterhoeven <geert@linux-m68k.org> [m68k]
Cc: Kyle McMartin <kyle@mcmartin.ca> [parisc]
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> [powerpc]
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> [s390]
Cc: Thomas Gleixner <tglx@linutronix.de> [x86]
Cc: Ingo Molnar <mingo@redhat.com> [x86]
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

1 files changed, 16 insertions, 0 deletions

diff --git a/Documentation/kbuild/kbuild.txt b/Documentation/kbuild/kbuild.txt
index f3355b6812d..bb3bf38f03d 100644
--- a/Documentation/kbuild/kbuild.txt
+++ b/Documentation/kbuild/kbuild.txt
@@ -65,6 +65,22 @@ INSTALL_PATH
 INSTALL_PATH specifies where to place the updated kernel and system map
 images. Default is /boot, but you can set it to other values.
 
+INSTALLKERNEL
+--------------------------------------------------
+Install script called when using "make install".
+The default name is "installkernel".
+
+The script will be called with the following arguments:
+    $1 - kernel version
+    $2 - kernel image file
+    $3 - kernel map file
+    $4 - default install path (use root directory if blank)
+
+The implmentation of "make install" is architecture specific
+and it may differ from the above.
+
+INSTALLKERNEL is provided to enable the possibility to
+specify a custom installer when cross compiling a kernel.
 
 MODLIB
 --------------------------------------------------