[PATCH v4 08/10] rockchip: binman: Use the skip-at-start prop in simple-bin image

[Simon Glass]

Hi Quentin,

On Wed, 9 Apr 2025 at 04:57, Quentin Schulz <quentin.schulz at cherry.de> wrote:
>
> Hi Jonas, Simon,
>
> On 3/29/25 4:06 PM, Jonas Karlman wrote:
> > From: Simon Glass <sjg at chromium.org>
> >
> > The simple-bin image is normally written to MMC media at block 64, which
> > is a 32K offset from start of storage media.
> >
> > Set the skip-at-start property to 0x8000 (32 KiB) so that fdtmap and
> > other embedded binman symbols in the output binary is referencing image
> > offsets correctly.
> >
>
> Shouldn't we have this commit BEFORE we add the `fdtmap` node since we
> know it's wrong before this commit?
>
> > Signed-off-by: Simon Glass <sjg at chromium.org>
> > Signed-off-by: Jonas Karlman <jonas at kwiboo.se>
> > ---
> > Changes in v4:
> > - Drop defconfig changes
> > - Split from "VBE serial part H: Implement VBE on Rockchip RK3399"
> >
> > Changes in v2:
> > - Move this patch to the end of the series
> > - Drop 0x8000 offset for SPI
> > ---
> >   arch/arm/dts/rockchip-u-boot.dtsi | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm/dts/rockchip-u-boot.dtsi b/arch/arm/dts/rockchip-u-boot.dtsi
> > index fb38b7b80c43..65b81bf58626 100644
> > --- a/arch/arm/dts/rockchip-u-boot.dtsi
> > +++ b/arch/arm/dts/rockchip-u-boot.dtsi
> > @@ -154,6 +154,7 @@
> >       simple-bin {
> >               filename = "u-boot-rockchip.bin";
> >               pad-byte = <0xff>;
> > +             skip-at-start = <0x8000>;
> >
> >               mkimage {
> >                       filename = "idbloader.img";
> > @@ -178,7 +179,7 @@
> >   #else
> >               u-boot-img {
> >   #endif
> > -                     offset = <CONFIG_SPL_PAD_TO>;
> > +                     offset = <(CONFIG_SPL_PAD_TO + 0x8000)>;
>
> This is confusing. The documentation states:
>
> """
> offset:
>      This sets the offset of an entry within the image or section containing
>      it.
> """
>
> My understanding is that it should be relative to the beginning of the
> image but this now needs the knowledge of where it will be stored on the
> MMC device (via the value in skip-at-start).
>
> Why is skip-at-start automatically deducted from offset?

This is how binman works[1]. We are trying to use the feature designs
for this purpose (dealing with implied / missing chunks at the start
of an image). At this point in the series CONFIG_SPL_PAD_TO is set to
0x78000 I believe, so we need to add another 0x8000 to get the offset
that binman uses.

Regards,
Simon

[1] https://docs.u-boot.org/en/latest/develop/package/binman.html#image-properties