[U-Boot] [PATCH 17/17] 85xx: Use gc-sections to reduce image size

Peter Tyser
2010-09-29T19:05:56Z

On an XPedite5370 over 11KBytes were saved:
Before:
text data bss dec hex filename
332456 33364 33476 399296 617c0 ./u-boot

After:
text data bss dec hex filename
321075 33836 33476 388387 5ed23 ./u-boot

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
CC: Kumar Gala <galak@kernel.crashing.org>
---
arch/powerpc/cpu/mpc85xx/config.mk | 4 +++
arch/powerpc/cpu/mpc85xx/u-boot.lds | 52 +++++++----------------------------
2 files changed, 14 insertions(+), 42 deletions(-)

diff --git a/arch/powerpc/cpu/mpc85xx/config.mk b/arch/powerpc/cpu/mpc85xx/config.mk
index f07d920..ce4376b 100644
--- a/arch/powerpc/cpu/mpc85xx/config.mk
+++ b/arch/powerpc/cpu/mpc85xx/config.mk
@@ -25,6 +25,10 @@ PLATFORM_RELFLAGS += -fPIC -meabi

PLATFORM_CPPFLAGS += -ffixed-r2 -Wa,-me500 -msoft-float -mno-string

+# Enable gc-sections to enable generation of smaller images.
+PLATFORM_LDFLAGS += --gc-sections
+PLATFORM_RELFLAGS += -ffunction-sections -fdata-sections
+
# -mspe=yes is needed to have -mno-spe accepted by a buggy GCC;
# see "[PATCH,rs6000] make -mno-spe work as expected" on
# http://gcc.gnu.org/ml/gcc-patches/2008-04/msg00311.html
diff --git a/arch/powerpc/cpu/mpc85xx/u-boot.lds b/arch/powerpc/cpu/mpc85xx/u-boot.lds
index c88b1f3..85042c5 100644
--- a/arch/powerpc/cpu/mpc85xx/u-boot.lds
+++ b/arch/powerpc/cpu/mpc85xx/u-boot.lds
@@ -25,8 +25,7 @@
#endif

OUTPUT_ARCH(powerpc)
-/* Do we need any of these for elf?
- __DYNAMIC = 0; */
+
PHDRS
{
text PT_LOAD;
@@ -38,42 +37,16 @@ SECTIONS
/* Read-only sections, merged into text segment: */
. = + SIZEOF_HEADERS;
.interp : { *(.interp) }
- .hash : { *(.hash) }
- .dynsym : { *(.dynsym) }
- .dynstr : { *(.dynstr) }
- .rel.text : { *(.rel.text) }
- .rela.text : { *(.rela.text) }
- .rel.data : { *(.rel.data) }
- .rela.data : { *(.rela.data) }
- .rel.rodata : { *(.rel.rodata) }
- .rela.rodata : { *(.rela.rodata) }
- .rel.got : { *(.rel.got) }
- .rela.got : { *(.rela.got) }
- .rel.ctors : { *(.rel.ctors) }
- .rela.ctors : { *(.rela.ctors) }
- .rel.dtors : { *(.rel.dtors) }
- .rela.dtors : { *(.rela.dtors) }
- .rel.bss : { *(.rel.bss) }
- .rela.bss : { *(.rela.bss) }
- .rel.plt : { *(.rel.plt) }
- .rela.plt : { *(.rela.plt) }
- .init : { *(.init) }
- .plt : { *(.plt) }
.text :
{
- *(.text)
- *(.got1)
+ *(.text*)
} :text
_etext = .;
PROVIDE (etext = .);
.rodata :
{
- *(.eh_frame)
*(SORT_BY_ALIGNMENT(SORT_BY_NAME(.rodata*)))
} :text
- .fini : { *(.fini) } =0
- .ctors : { *(.ctors) }
- .dtors : { *(.dtors) }

/* Read-write section, merged into data segment: */
. = (. + 0x00FF) & 0xFFFFFF00;
@@ -81,23 +54,19 @@ SECTIONS
PROVIDE (erotext = .);
.reloc :
{
- *(.got)
+ KEEP(*(.got))
_GOT2_TABLE_ = .;
- *(.got2)
+ KEEP(*(.got2))
_FIXUP_TABLE_ = .;
- *(.fixup)
+ KEEP(*(.fixup))
}
__got2_entries = (_FIXUP_TABLE_ - _GOT2_TABLE_) >> 2;
__fixup_entries = (. - _FIXUP_TABLE_) >> 2;

.data :
{
- *(.data)
- *(.data1)
- *(.sdata)
- *(.sdata2)
- *(.dynamic)
- CONSTRUCTORS
+ *(.data*)
+ *(.sdata*)
}
_edata = .;
PROVIDE (edata = .);
@@ -126,7 +95,7 @@ SECTIONS

.resetvec RESET_VECTOR_ADDRESS :
{
- *(.resetvec)
+ KEEP(*(.resetvec))
} :text = 0xffff

. = RESET_VECTOR_ADDRESS + 0x4;
@@ -145,9 +114,8 @@ SECTIONS
__bss_start = .;
.bss (NOLOAD) :
{
- *(.sbss) *(.scommon)
- *(.dynbss)
- *(.bss)
+ *(.sbss*)
+ *(.bss*)
*(COMMON)
} :bss

--
1.7.0.4