Re: [PATCH 2/2] docs: add no-padding firmware feature

[Kashyap Chamarthy <kchamart@redhat.com>]

On Fri, Dec 16, 2022 at 11:12:34AM +0100, Gerd Hoffmann wrote:

Hi,

> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  docs/interop/firmware.json | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/docs/interop/firmware.json b/docs/interop/firmware.json
> index 56814f02b3c0..74f404d745b0 100644
> --- a/docs/interop/firmware.json
> +++ b/docs/interop/firmware.json
> @@ -191,6 +191,8 @@
>  #                  PL011 UART. @verbose-static is mutually exclusive
>  #                  with @verbose-dynamic.
>  #
> +# @no-padding: The (arm/aarch64) firmware images are not padded to 64M.
> +#
>  # Since: 3.0
>  ##
>  { 'enum' : 'FirmwareFeature',
> @@ -198,7 +200,8 @@
>               'amd-sev', 'amd-sev-es', 'amd-sev-snp',
>               'intel-tdx',
>               'enrolled-keys', 'requires-smm', 'secure-boot',
> -             'verbose-dynamic', 'verbose-static' ] }
> +             'verbose-dynamic', 'verbose-static',
> +             'no-padding' ] }

If you're re-spinning, please consider adding a sentence or two (for
those of us who're not familiar) a bit more about the "no-padding"
feature to the commit message.

IIUC, I found the use of the padding feature reading an old email
response[1] from Dan Berrangé:

(quote)
    ...
    If there's a risk that newer firmware will be larger than old firmware
    there's only really two options:
    
      - Keep all firmware images forever, each with a unique versioned
        filename. This ensures target QEMU will always load the original
        smaller firmware
    
      - Add padding to the firmware images. IOW, if the firmware is 2 MB,
        add zero-padding to the end of the image to round it upto 4 MB
        (whatever you anticipate the largest size wil be in future).
    ...
(/quote)


[1] https://edk2.groups.io/g/devel/message/54758

Regardless:

Reviewed-by: Kashyap Chamarthy <kchamart@redhat.com>

>  ##
>  # @FirmwareFlashFile:
> -- 
> 2.38.1
> 

-- 
/kashyap