Hi Simon,

On 4/9/25 4:30 PM, Simon Glass wrote:
Hi Quentin,

On Wed, 9 Apr 2025 at 07:35, Quentin Schulz <quentin.sch...@cherry.de> wrote:

Hi Simon,

On 4/9/25 3:33 PM, Simon Glass wrote:
Hi Quentin,

On Wed, 9 Apr 2025 at 07:32, Quentin Schulz <quentin.sch...@cherry.de> wrote:

Hi Simon,

On 4/9/25 3:22 PM, Simon Glass wrote:
Hi Quentin,

On Wed, 9 Apr 2025 at 04:57, Quentin Schulz <quentin.sch...@cherry.de> wrote:

Hi Jonas, Simon,

On 3/29/25 4:06 PM, Jonas Karlman wrote:
From: Simon Glass <s...@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 <s...@chromium.org>
Signed-off-by: Jonas Karlman <jo...@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

Why is it deducted?

Are you asking why skip-at-start is deducted from the offset?


Yes

It is confusing, unfortunately.

When you use an offset (say 0x78000) then normally the entry will
start at that offset in the image.

When you use skip-at-start 0x8000, its value is added to all top-level
offsets in the image, so the offset becomes 0x80000

BUT the image built by binman does not contain the first 0x8000 bytes.
It is expected that the image is written to offset 0x8000 so that the
offsets will be correct when used within U-Boot itself.


I would assume all offsets are relative to the beginning of the image in the binary? Adding skip-at-start doesn't add 0x8000 bytes at the beginning of the binary file, so why would the offsets need to be modified?

Also, while 0x8000 is the typical address the image can be flashed, it is not necessarily where it will be as the BootROM tries a few other offsets if it cannot find one at 32KiB offset in the storage medium. This seems to me to be a case of "somewhat helps in one case, but makes things more confusing in others"? Will we need different offsets depending on where the FIT is flashed? What happens for A/B updates then?

I understand that we currently essentially have skip-at-start = 0; and that it is bad because it doesn't reflect the actual address, but how is that worse than hardcoding a different offset?

Cheers,
Quentin

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