[PATCH v5] docs: Correct FW_JUMP_FDT_ADDR calculation example

[Anup Patel]

On Fri, Mar 31, 2023 at 1:55 AM Gabriel Somlo <gsomlo at gmail.com> wrote:
>
> When using `PLATFORM=generic` defaults, the kernel is loaded at
> `FW_JUMP_ADDR`, and the FDT is loaded at `FW_JUMP_FDT_ADDR.
>
> Therefore, the maximum kernel size before `FW_JUMP_FDT_ADDR` must
> be increased is `$(( FW_JUMP_FDT_ADDR - FW_JUMP_ADDR ))`.
>
> The example calculation assumes `rv64`, and is wrong to boot
> (off by 0x200000). Fix it and update it for the general case.
>
> Signed-off-by: Gabriel Somlo <gsomlo at gmail.com>
> Reviewed-by: Andrew Jones <ajones at ventanamicro.com>
> Reviewed-by: Xiang W <wxjstz at 126.com>

Applied this patch to the riscv/opensbi repo.

Thanks,
Anup

> ---
>  docs/firmware/fw_jump.md | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/docs/firmware/fw_jump.md b/docs/firmware/fw_jump.md
> index 956897e..3e883fa 100644
> --- a/docs/firmware/fw_jump.md
> +++ b/docs/firmware/fw_jump.md
> @@ -43,18 +43,18 @@ follows:
>
>    When using the default *FW_JUMP_FDT_ADDR* with *PLATFORM=generic*, you must
>    ensure *FW_JUMP_FDT_ADDR* is set high enough to avoid overwriting the kernel.
> -  You can use the following method.
> +  You can use the following method (e.g., using bash or zsh):
>
>    ```
> -  ${CROSS_COMPILE}objdump -h $KERNEL_ELF | sort -k 5,5 | awk -n '/^ +[0-9]+ /\
> -  {addr="0x"$3; size="0x"$5; printf "0x""%x\n",addr+size}' \
> -  | (( `tail -1` > 0x2200000 )) && echo fdt overlaps kernel,\
> -  increase FW_JUMP_FDT_ADDR
> +  ${CROSS_COMPILE}objdump -h $KERNEL_ELF | sort -k 5,5 | awk -n '
> +  /^ +[0-9]+ / {addr="0x"$3; size="0x"$5; printf "0x""%x\n",addr+size}' |
> +  (( `tail -1` > (FW_JUMP_FDT_ADDR - FW_JUMP_ADDR) )) &&
> +  echo fdt overlaps kernel, increase FW_JUMP_FDT_ADDR
>
> -  ${LLVM}objdump -h --show-lma $KERNEL_ELF | sort -k 5,5 | \
> -  awk -n '/^ +[0-9]+ / {addr="0x"$3; size="0x"$5; printf "0x""%x\n",addr+size}'\
> -  | (( `tail -1` > 0x2200000 )) && echo fdt overlaps kernel,\
> -  increase FW_JUMP_FDT_ADDR
> +  ${LLVM}objdump -h --show-lma $KERNEL_ELF | sort -k 5,5 | awk -n '
> +  /^ +[0-9]+ / {addr="0x"$3; size="0x"$5; printf "0x""%x\n",addr+size}' |
> +  (( `tail -1` > (FW_JUMP_FDT_ADDR - FW_JUMP_ADDR) )) &&
> +  echo fdt overlaps kernel, increase FW_JUMP_FDT_ADDR
>    ```
>
>  *FW_JUMP* Example
> --
> 2.39.2
>
>
> --
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