use gc sections to reduce image size

I have run a quick test on x86 with a saving of 5.8kB with no apparent problems. NOTE: If I add -fdata-sections as per the NIOS patches, U-Boot fails to run.

I'm in the middle of a major re-write of the x86 startup code and will include this as a formal patch when that work is complete.

Regards,

Graeme

index 4b990e0..0e80a1a 100644
@@ -26,3 +26,6 @@ CROSS_COMPILE ?= i386-linux-
 STANDALONE_LOAD_ADDR = 0x40000
 
 PLATFORM_CPPFLAGS += -DCONFIG_I386 -D__I386__
+
+LDFLAGS += --cref --gc-sections
+PLATFORM_RELFLAGS += -ffunction-sections

index d78d75f..7b211a8 100644
@@ -77,13 +77,13 @@ SECTIONS
 	_i386boot_bss_size = SIZEOF(.bss);
 
 	/* 16bit realmode trampoline code */
-	.realmode 0x7c0 : AT ( LOADADDR(.rel.dyn) + SIZEOF(.rel.dyn) ) {

*(.realmode) }
+ .realmode 0x7c0 : AT ( LOADADDR(.rel.dyn) + SIZEOF(.rel.dyn) ) {
KEEP(*(.realmode)) }

_i386boot_realmode = LOADADDR(.realmode); _i386boot_realmode_size = SIZEOF(.realmode);

/* 16bit BIOS emulation code (just enough to boot Linux) */
- .bios 0 : AT ( LOADADDR(.realmode) + SIZEOF(.realmode) ) { *(.bios) }
+ .bios 0 : AT ( LOADADDR(.realmode) + SIZEOF(.realmode) ) { KEEP(*(.bios)) }

_i386boot_bios = LOADADDR(.bios); _i386boot_bios_size = SIZEOF(.bios);
@@ -98,12 +98,12 @@ SECTIONS
* The fff0 offset of resetvec is important, however. */
. = 0xfffffe00;
- .start32 : AT (TEXT_BASE + 0x3fe00) { *(.start32); }
+ .start32 : AT (TEXT_BASE + 0x3fe00) { KEEP(*(.start32)); }

. = 0xf800;
- .start16 : AT (TEXT_BASE + 0x3f800) { *(.start16); }
+ .start16 : AT (TEXT_BASE + 0x3f800) { KEEP(*(.start16)); }

. = 0xfff0;
- .resetvec : AT (TEXT_BASE + 0x3fff0) { *(.resetvec); }
+ .resetvec : AT (TEXT_BASE + 0x3fff0) { KEEP(*(.resetvec)); }
_i386boot_end = (LOADADDR(.resetvec) + SIZEOF(.resetvec) );
}