On Sat, Oct 9, 2010 at 4:10 PM, Albert ARIBAUD albert.aribaud@free.fr wrote:
Le 09/10/2010 09:53, Lei Wen a écrit :
Hi Albert,
On Sat, Oct 9, 2010 at 3:43 PM, Albert ARIBAUDalbert.aribaud@free.fr wrote:
Le 09/10/2010 07:50, Lei Wen a écrit :
Hi,
I recently try to port our board code to new uboot, which has been changed to use new relocation scheme. But I found a very strange thing, that is if the uboot is loaded to the TEXT_BASE address, it could run without problem. But if it is loaded to a different place, it fail to boot up...
I check the code, and found that in the board_init_f, it calls the init_sequence which is stored as a data sector in the u-boot.bin file. While the new scheme use the fPIC, the code could locate the GOT table correctly, and it seem to forgot what the GOT table stores is context that is meaningful in TEXT_BASE, not the loaded base. That is to say, if the TEXT_BASE is 0xf00000, and loaded base is 0x500000, I found the GOT table also filled with 0xf0****, not the 0x50****. This leads the cpu loading wrong function address in the init_sequence table, and cause pc become invalid...
Am I missing something to switch to the new relocation scheme?
Thanks, Lei
Can you indicate which hardware (architecture, cpu, SoC, etc) you're running this code on?
I am running the code on Marvell aspen soc, which is arm926ejs compatible core.
For arm926, TEXT_BASE should be the FLASH location (if booting from NOR) or a location in DRAM (for NAND and other methods).
Yeah, got that. The TEXT_BASE of 0xf00000 in my case is the exactly what I want to uboot run during its run time.
I have had little difficulty in running the .got relocation code in a Marvell oront5x (arm926ejs too), except for some functions called from board_init_f which did not respect the general rule that code run before relocation should only access gd; one place in orion5x wrote to global variables, which always was a no-no and only happened to work because the arm926ejs init sequence did not run in proper order.
Have you tried load the uboot to different place with tftp or something else? When I load the uboot to the TEXT_BASE and run, there is also no issue...
However, .got relocation has shortcomings of its own; mainly, it requires manual fixups in many places within the code. I have provided patches which replace .got relocation with ELF relocation (look up [ELF-RELOC] tags in the posts), which eliminates the need for any manual fixup; you may want to try this, as it might eventually replace the .got patches.
Glad to hear this. :-) But my problem is before relocating, the new scheme call the init_sequence in board_init_f, while the TEXT_BASE keep the function entry as static value during compile time. Does the ELF relocation could bring us a relative jump when call the init_sequence table?
Thanks, Lei