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

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Date:	Fri, 7 Aug 2009 23:08:16 +0200
From:	Sam Ravnborg <sam@...nborg.org>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	Albin Tonnerre <albin.tonnerre@...e-electrons.com>,
	Matthieu CASTET <matthieu.castet@...rot.com>,
	Alain Knaff <alain@...ff.lu>, "hpa@...or.com" <hpa@...or.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-embedded@...r.kernel.org" <linux-embedded@...r.kernel.org>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
Subject: Re: [PATCH 4/6] Add support for LZO-compressed kernels for ARM

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@...nborg.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
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