Re: [PATCH 4/6] Add support for LZO-compressed kernels for ARM

Sam Ravnborg
2009-08-07T21:08:20Z

On Fri, Aug 07, 2009 at 09:00:01PM +0100, Russell King - ARM Linux wrote:
> On Fri, Aug 07, 2009 at 03:55:24PM +0200, Albin Tonnerre wrote:
> > That's true for the actual kernel image, but not for the bootstrap code we use
> > when compiling compressed kernels. arch/arm/boot/compressed/Makefile uses
> > libgcc, unless I'm overlooking something here:
> >
> > arm-unknown-linux-uclibcgnueabi-ld -EL --defsym zreladdr=0x20008000
> > --defsym initrd_phys=0x20410000 --defsym params_phys=0x20000100 -p
> > --no-undefined -X
> > /home/albin/x-tools/arm-unknown-linux-uclibcgnueabi/lib/gcc/arm-unknown-linux-uclibcgnueabi/4.3.2/libgcc.a
> > -T arch/arm/boot/compressed/vmlinux.lds arch/arm/boot/compressed/head.o
> > arch/arm/boot/compressed/piggy.gzip.o arch/arm/boot/compressed/misc.o -o
> > arch/arm/boot/compressed/vmlinux
>
> It's because libgcc appears in the wrong place in the command line, and
> due to the way kbuild works, we can't get it into the right place easily.
>
> Linkers are sensitive to the order of archives on the command line - its
> pointless having an archive as the first file argument because none of
> the contained objects will ever be pulled in.
>
> Sam - any ideas how to solve this?

We could add libgcc as a prerequisite.
Untested patch below.

This is a ittle hackish - otherwise we have to change the
definition of ld or use a private version.

I added explanations for some of the linker symbols when
I was there. I cannot the ld options.

If you decide to use this it has my:

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Sam

diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile
index ce39dc5..4f980f2 100644
--- a/arch/arm/boot/compressed/Makefile
+++ b/arch/arm/boot/compressed/Makefile
@@ -87,15 +87,24 @@ endif
ifneq ($(PARAMS_PHYS),)
LDFLAGS_vmlinux += --defsym params_phys=$(PARAMS_PHYS)
endif
-LDFLAGS_vmlinux += -p --no-undefined -X \
- $(shell $(CC) $(KBUILD_CFLAGS) --print-libgcc-file-name) -T
+
+# ?
+LDFLAGS_vmlinux += -p
+# Report unresolved symbol references
+LDFLAGS_vmlinux += --no-undefined
+# Delete all temporary local symbols
+LDFLAGS_vmlinux += -X
+# Next argument is a linker script
+LDFLAGS_vmlinux += -T
+
+libgcc = $(shell $(CC) $(KBUILD_CFLAGS) --print-libgcc-file-name)

# Don't allow any static data in misc.o, which
# would otherwise mess up our GOT table
CFLAGS_misc.o := -Dstatic=

$(obj)/vmlinux: $(obj)/vmlinux.lds $(obj)/$(HEAD) $(obj)/piggy.o \
- $(addprefix $(obj)/, $(OBJS)) FORCE
+ $(addprefix $(obj)/, $(OBJS)) $(libgcc) FORCE
$(call if_changed,ld)
@:

Sam