Re: [ImageBuilder PATCH] uboot-script-gen: use size from arm64 Image header

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Thu, 24 Aug 2023, Stewart Hildebrand wrote:
> There is a corner case where the filesizes of the xen and Linux kernel images
> are not sufficient. These binaries likely contain .NOLOAD sections, which are
> not accounted in the filesize.
> 
> Check for the presence of an arm64 kernel image header, and get the effective
> image size from the header. Use the effective image size for calculating the
> next load address and for populating the size in the /chosen/dom*/reg 
> property.
> 
> Signed-off-by: Stewart Hildebrand <stewart.hildebrand@xxxxxxx>
> ---
>  scripts/uboot-script-gen | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/uboot-script-gen b/scripts/uboot-script-gen
> index 9656a458ac00..50fe525e7145 100755
> --- a/scripts/uboot-script-gen
> +++ b/scripts/uboot-script-gen
> @@ -2,7 +2,7 @@
>  
>  offset=$((2*1024*1024))
>  filesize=0
> -prog_req=(mkimage file fdtput mktemp awk)
> +prog_req=(mkimage file fdtput mktemp awk od)
>  
>  function cleanup_and_return_err()
>  {
> @@ -435,6 +435,17 @@ function add_size()
>  {
>      local filename=$1
>      local size=`stat -L --printf="%s" $filename`
> +
> +    if [ "$(od -j 56 -N 4 -t x4 ${filename} | head -n 1 | awk -F' ' '{ print 
> $2 }')" = "644d5241" ]
> +    then
> +        local size_header=$(od -j 16 -N 8 -t u8 ${filename} | head -n 1 | 
> awk -F' ' '{ print $2 }')
> +
> +        if [ "${size_header}" -gt "${size}" ]
> +        then
> +            size=${size_header}
> +        fi
> +    fi


Thanks Stewart this is great! Can you please add a good in-code comment
to explain what field you are reading of the header exactly and what is
the value 644d5241 you are comparing against?

Also I think it would be easier to read if you used "cut" instead of
awk and split the line a bit more like this:


    # read header field XXX
    local field_xxx =$(od -j 56 -N 4 -t x4 ${filename} | head -n 1 | cut -d " " 
-f2)
    # comparing against XXX
    if [ $field_xxx = "644d5241" ]
    then
        # read header field "size" which indicates ....
        local size_header=$(od -j 16 -N 8 -t u8 ${filename} | head -n 1 | cut 
-d " " -f2)

        if [ "${size_header}" -gt "${size}" ]
        then
            size=${size_header}
        fi
    fi


>      memaddr=$(( $memaddr + $size + $offset - 1))
>      memaddr=$(( $memaddr & ~($offset - 1) ))
>      memaddr=`printf "0x%X\n" $memaddr`
> -- 
> 2.42.0
>