U-boot must be linked to the correct startup address in flash so that global data acceses work before relocation to RAM.
This patch demonstrates the changes needed in common code needed to run from any link address. With these changes and a few asm insn in start.S I can link my u-boot to address 0 and still boot linux.
I am posting this for comment only and what I want to know if this change to common code is accepable or not. if so, I will send a formal patch for 83xx
The size cost is about 500 text bytes: text data bss dec hex filename 229544 14876 27608 272028 4269c u-boot 230008 14872 27608 272488 42868 u-boot.link_off
link_off looks like this currently: .globl link_off /* const void * link_off(const void * ptr) */ link_off: /* Adds GOT offset to ptr, might be useful for true PIC too */ /* Would be great if this could be inline C __asm__ instead */ /* Hand coded as we cannot clobber r14 when called from C */ mflr r4 bl 1f .text 2 0: .long .LCTOC1-1f .text 1: mflr r6 lwz r0,0b-1b(r6) add r6,r0,r6 mtlr r4 la r4,.L__GOT2_TABLE_(r6) /* addi r4,r6,.L__GOT2_TABLE_ */ lwz r5,.L__GOT2_TABLE_(r6) sub r4,r5,r4 /* r4 - r5 */ sub r3,r3,r4 /* r4 - r3 */ blr
WD, what do you think?
Joakim Tjernlund (2): Use LINK_OFF to access global data Use LINK_OFF in enviroment too
common/cmd_nvedit.c | 2 + common/console.c | 12 ++++++-- common/env_common.c | 2 +- common/env_flash.c | 65 ++++++++++++++++++++++++---------------- cpu/mpc83xx/cpu.c | 10 +++--- cpu/mpc83xx/cpu_init.c | 26 +++++++++------- cpu/mpc83xx/speed.c | 28 +++++++----------- drivers/serial/serial.c | 21 +++++++------ include/common.h | 1 - include/linux/ctype.h | 6 ++-- lib_generic/crc32.c | 7 ++++- lib_generic/ctype.c | 2 +- lib_generic/display_options.c | 5 ++- lib_generic/vsprintf.c | 9 ++++-- lib_ppc/board.c | 5 ++- tools/updater/ctype.c | 2 +- 16 files changed, 115 insertions(+), 88 deletions(-)