[PATCH v3] docs: Correct FW_JUMP_FDT_ADDR calculation example

[Xiang W]

在 2023-03-24星期五的 08:07 -0400，Gabriel Somlo写道：
> 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>
> ---
>  docs/firmware/fw_jump.md | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/docs/firmware/fw_jump.md b/docs/firmware/fw_jump.md
> index 956897e..ed3a43e 100644
> --- a/docs/firmware/fw_jump.md
> +++ b/docs/firmware/fw_jump.md
> @@ -46,15 +46,15 @@ follows:
>    You can use the following method.
>  
>    ```
> -  ${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) )) &&
FW_JUMP_FDT_ADDR and FW_JUMP_ADDR should be variables in the shell,
and references need to use $ as the starting char.

> +  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) )) &&
Same as above

Regards,
Xiang W
> +  echo fdt overlaps kernel, increase FW_JUMP_FDT_ADDR
>    ```
>  
>  *FW_JUMP* Example
> -- 
> 2.39.2
> 
>