TOC1 is an container format used by Allwinner's boot0 that can hold
multiple images. It supports encryption and signatures, but that
functionality is not implemented, only the basic "non-secure" subset.
A config file is used to provide the list of data files to include. Its
path is passed as the argument to "-d". It contains sections of the
following form:
[name]
file = /path/to/file
addr = 0x12345678
Specific well-known names, such as "dtb", "opensbi", and "u-boot", are
used by the bootloader to distinguish the items inside the image.
Cover-letter:
tools: mkimage: Add Allwinner TOC1 support
The SPL port for the Allwinner D1 RISC-V SoC will probably take a while
longer than porting U-Boot proper, as none of the relevant drivers are
set up for DM in SPL. In the meantime, we are using[1][2] a fork[3] of
Allwinner's boot0 loader, which they also call "spl" in their BSP. boot0
uses this TOC1 image format.
The vendor tools for generating TOC1 images require a binary config file
generated by their FEX compiler. Instead of trying to support that, I
made up a simple human-readable config file format. I didn't see any
existing platform-agnostic parser for multi-image containers in mkimage.
I am sending this as RFC because it is only of temporary/limited use.
It only works with one specific fork of boot0 which was modified to
"behave" (the the original vendor version monkey-patches a custom header
inside the U-Boot image during boot). So it will be obsolete once U-Boot
SPL is ported. And it is Yet Another Image Format. On the other hand, it
does work, and it is currently being used.
[1]: https://linux-sunxi.org/Allwinner_Nezha#U-Boot
[2]: https://fedoraproject.org/wiki/Architectures/RISC-V/Allwinner
[3]: https://github.com/smaeul/sun20i_d1_spl
END
Series-prefix: RFC
Series-to: sunxi
Signed-off-by: Samuel Holland <samuel@sholland.org>
