[PATCH 13/15] bootwrapper: attach an empty vmlinux

[Milton Miller <miltonm@bga.com>]

Allow the boot wrapper code to be linked without an attached vmlinux.

Rather than invent a new syntax to invoke the wrapper, attach the
stripped version of empty.o, which produces the same result.

This new intermediary is called zBoot.

Signed-off-by: Milton Miller <miltonm@bga.com>
--- 
vs 12180
context diffs, identical content

Iniital attempts to remove the dependency on vmlinux in the arch Makefile
have lead to multiple make commands competeing in the boot directory and
destroying each other.  Until the make rules are fixed, the full kenrel
must be built.

There are parallel make conflicts when specifying a dts file to be
compiled into the binary unaffected by this patch, except one may
choose more targets showing the problems..

Index: kernel/arch/powerpc/boot/Makefile
===================================================================
--- kernel.orig/arch/powerpc/boot/Makefile	2007-09-17 22:11:51.000000000 -0500
+++ kernel/arch/powerpc/boot/Makefile	2007-09-17 22:12:05.000000000 -0500
@@ -126,7 +126,8 @@ endif
 # args (to if_changed): 1 = (this rule), 2 = platform, 3 = dts 4=dtb 5=initrd
 quiet_cmd_wrap	= WRAP    $@
       cmd_wrap	=$(CONFIG_SHELL) $(wrapper) -c -o $@ -p $2 $(CROSSWRAP) \
-		$(if $3, -s $3)$(if $4, -d $4)$(if $5, -i $5) vmlinux
+		$(if $3, -s $3)$(if $4, -d $4)$(if $5, -i $5) \
+		$(if $6,$6,vmlinux)
 
 kexec-$(CONFIG_PPC32)			+= zImage.kexec
 kexec-$(CONFIG_PPC64)			+= zImage.kexec64
@@ -144,6 +145,7 @@ image-$(CONFIG_PPC_PRPMC2800)		+= zImage
 image-$(CONFIG_PPC_ISERIES)		+= zImage.iseries
 image-$(CONFIG_DEFAULT_UIMAGE)		+= uImage
 image-$(CONFIG_KEXEC)			+= $(kexec-y)
+image-$(CONFIG_KEXEC)			+= $(patsubst zImage%,zBoot%,$(kexec-y))
 
 ifneq ($(CONFIG_DEVICE_TREE),"")
 image-$(CONFIG_PPC_8xx)			+= cuImage.8xx
@@ -197,6 +199,9 @@ $(obj)/vmlinux.strip: vmlinux
 $(obj)/zImage.iseries: vmlinux
 	$(STRIP) -s -R .comment $< -o $@
 
+$(obj)/zBoot.%: $(wrapperbits) $(dts)
+	$(call if_changed,wrap,$*,$(dts),,,$(obj)/empty.o)
+
 $(obj)/zImage.ps3: vmlinux  $(wrapper) $(wrapperbits) $(srctree)/$(src)/dts/ps3.dts
 	$(STRIP) -s -R .comment $< -o vmlinux.strip
 	$(call cmd,wrap,ps3,$(srctree)/$(src)/dts/ps3.dts,,)
@@ -234,7 +239,7 @@ clean-files += $(image-) $(initrd-) zIma
 	otheros.bld $(kexec-)
 
 # clean up files cached by wrapper
-clean-kernel := vmlinux.strip vmlinux.bin
+clean-kernel := vmlinux.strip vmlinux.bin empty.o.bin
 clean-kernel += $(addsuffix .gz,$(clean-kernel))
 # If not absolute clean-files are relative to $(obj).
 clean-files += $(addprefix $(objtree)/, $(clean-kernel))
Index: kernel/arch/powerpc/boot/wrapper
===================================================================
--- kernel.orig/arch/powerpc/boot/wrapper	2007-09-17 22:11:51.000000000 -0500
+++ kernel/arch/powerpc/boot/wrapper	2007-09-17 22:12:05.000000000 -0500
@@ -161,6 +161,13 @@ ps3)
     ;;
 esac
 
+if [ "$kernel" = $object/empty.o ] ; then
+    ext=bin
+    objflags="-O binary"
+    gzip=
+fi
+
+
 vmz="$tmpdir/`basename \"$kernel\"`.$ext"
 if [ -z "$cacheit" -o ! -f "$vmz$gzip" -o "$vmz$gzip" -ot "$kernel" ]; then
     ${CROSS}objcopy $objflags "$kernel" "$vmz.$$"