When we run U-Boot in S-mode the BBL runs from 0x80000000 so this two lines corrupts BBL instructions.
Hi Anup
You said Your patchset based upon git://git.denx.de/u-boot-riscv.git
Why you announce this problem in [PATCH v5 4/4] riscv: Remove redundant a2 store on DRAM base in start.S Why you do not find this proble in v1, v2, v3, v4 ?
Rick
If this is important for some board then please have it around #ifdef.
Hi Anup
In the discussion as below : https://www.mail-archive.com/u-boot@lists.denx.de/msg305880.html
I try to solve this issue with the aptch [PATCH] riscv: ax25-ae350: Pass dtb address to u-boot with a1 register diff --git a/arch/riscv/cpu/start.S b/arch/riscv/cpu/start.S
li t0, CONFIG_SYS_SDRAM_BASESREG a2, 0(t0)diff --git a/board/AndesTech/ax25-ae350/ax25-ae350.c b/board/AndesTech/ax25-ae350/ax25-ae350.c void *board_fdt_blob_setup(void) {
void **ptr = (void *)CONFIG_SYS_SDRAM_BASE;
void **ptr = (void *)&prior_stage_fdt_address;in the previous pull request.
But Bin do not agree with that I use prior_stage_fdt_address in board_fdt_blob_setup( ) I try to explain why I use it like that way. Then Bin have not any reply in the following mail. Finally I decide to drop this patch in the next pull request.
Hi Bin
How do you think about I recovery this patch to fix this issue ?
Actually, previous booting stage can pass location of FDT stored in flash to U-Boot. U-Boot requires FDT at a DRAM location which it can modify in-place before passing on to Linux kernel so we should relocate the FDT passed by previous booting stage to some board specific DRAM location.
My suggestion is as follows:
Instead of SDRAM_BASE, we can have new board specific config CONFIG_RISCV_PRIOR_FDT_BASE
If CONFIG_RISCV_PRIOR_FDT_BASE is defined/selected by config then in start.S copy-over the FDT from location pointed by "a1" register to location pointed by CONFIG_RISCV_PRIOR_FDT_BASE.
Hi Anup
It can not achieve dtb delivery at runtime.
Rick
I think you can copy-over FDT in C code too. You don't need to do in start.S.
In your board_fdt_blob_setup(), you can safely do: void **ptr = (void *)CONFIG_RISCV_PRIOR_FDT_BASE;
Regards, Anup