Hi Simon,
On Thu, 2015-12-17 at 18:36 +0800, Bin Meng wrote:
Hi Alexey,
On Thu, Dec 17, 2015 at 3:13 AM, Alexey Brodkin Alexey.Brodkin@synopsys.com wrote:
Hi Bin,
On Tue, 2015-12-15 at 20:45 +0800, Bin Meng wrote:
On Tue, Dec 15, 2015 at 6:06 PM, Alexey Brodkin Alexey.Brodkin@synopsys.com wrote:
Current implementation of disabled relocation only works for EFI.
In case of GD_FLG_SKIP_RELOC jump_to_copy() will return instead of jumping further in board_init_r() etc. And jump_to_copy() being the last call in init_sequence_f when returning simply triggers hang() in board_init_f(). Well for everything except ARM, SANDBOX and EFI_APP.
Not sure why ARM and SANBOX are here - I would assume it's all on purpose but as for EFI_APP this is an essential need for getting out of board_init_f() and jumping in board_init_r() immediately afterwards, see efi_main().
But what if in case of no relocation we jump in board_init_r() right from jump_to_copy()? In that case we remove one ifdef from board_init_f() and leave a chance to seamlessly re-use disabled relocation for other (non-EFI) cases.
Signed-off-by: Alexey Brodkin abrodkin@synopsys.com
Note I didn't test it for EFI because I don't know how to do that in simulation, please let me know if there's a simple way to do it.
Does doc/README.efi not help?
Yeah thanks for that obvious pointer. Still it requires some extra steps like obtaining/building EFI BIOS etc. Anyways I'll try to get this setup up and running.
But I did test it for ARC boards (with additional patches) that enable disabled relocation - these patches to follow once something similar to my proposal here is implemented.
Reviewed-by: Bin Meng bmeng.cn@gmail.com
Tested on QEMU, booting u-boot-app.efi with EFI firmware Tested-by: Bin Meng bmeng.cn@gmail.com
common/board_f.c | 11 ++++++++--- lib/efi/efi_app.c | 2 +- 2 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/common/board_f.c b/common/board_f.c index eac7c5e..2d60ed9 100644 --- a/common/board_f.c +++ b/common/board_f.c @@ -720,8 +720,14 @@ static int setup_reloc(void)
static int jump_to_copy(void) {
/** In case of no relocation nothing to do between "running from flash"* (init_f) and "running from ram" (init_r), so just jumping in* board_init_r().*/ if (gd->flags & GD_FLG_SKIP_RELOC)
return 0;
board_init_r((gd_t *)gd, gd->relocaddr);I tried to do more complicated things compared to booting in console like "usb start" and at that point faced an unexpected problem.
The thing is usually in between board_init_f() and board_init_r() we do a couple of things, most important for us here is stack pointer update. See in board_init_f() we use init stack which is usually (for most of arches except x86) is located at hardcoded address CONFIG_SYS_INIT_SP_ADDR which might easily point to quite limited special memory like on-chip SRAM or (which is the case) be in the very beginning of RAM.
This init stack as said above could be quite small - just enough for every everything in board_init_f(). But when something heavy is executed what may easily happen (and that happens for me on "usb start") - we'll get in unexpected memory location. In my case I'm hitting non-existing memory which precedes DDR. And that was quite fortunate because I was hitting exception and so was able to figure out what's wrong.
For me solution was in stack-pointer update right before calling board_init_r() in my start.S. And that required another line addition to jump_to_copy(): So now I'm having this: ------------------>8----------------- if (gd->flags & GD_FLG_SKIP_RELOC) { board_init_f_stack_update(gd->start_addr_sp); <-- Updating SP board_init_r((gd_t *)gd, gd->relocaddr); } ------------------>8-----------------
I'm not sure if all that makes sense for x86 EFI but would like to know your opinion if potential run out out stack may happen there as well.
For u-boot-app.efi, the stack is allocated by the EFI firmware, so I think we are fine here. If we change its SP without making the EFI firmware aware, I believe subsequent call to EFI boot services will fail.
Any thoughts on that patch? If no comments from your side please consider applying.
-Alexey