Hi Pali,
On Sat, Sep 17, 2022 at 12:37 AM Pali Rohár pali@kernel.org wrote:
On Friday 16 September 2022 22:34:52 Chris Packham wrote:
I do wonder if the boot seqence and xmodem stuff could be abstracted out to something that could be reused by other tools.
In the past I was thinking about it... but I come to the conclusion that it is easier to write specific tools which implements communication with just one BootROM. Trying to write one universal thing just opens a lot of issues and at the end it would do same thing like if you implement N independent applications and then additional "launcher" application which starts the correct one.
It looks like that most Marvell SoCs use xmodem protocol. Except 3720 which uses WTPTP. But as I figured out, every SoC use slightly modified protocol based on xmodem. So well, in theory "sx" would work. But if you want to have other features (like progress bar or bootrom output or speed change) then all this is bootrom specific and has to be implemented directly into xmodem state machine. So either you provide N xmodem implementations or try to create something "hookable" and since beginning I have feeling that "hooks" would just introduce new bugs and make it harder to debug.
kwboot is currently in the state that it supports kwbimage v0 and kwbimage v1 formats, which IIRC covers all 32-bit widely used SoCs from kirkwood, dove, armada and switches which integrates those CPUs, and probably also avanta. At lot of stages it expects valid kwbimage and that is why there is validation at the beginning. It injects 32-bit ARM binary code for changing UART speed and requires above SoC (as it touches internal registers, which are same on all those mentioned). It also contains workarounds for bugs in Armada 385 BootROMs.
I really think that kwboot is now in state when it is not easily possible to extend it for different platform without lot of energy and extra testing that it does not break something existing.
Having looked more into mox-imager (and WtpDownloader) I've realised that the AlleyCat5 uses something called "TIM" but it's different to the format used by Armada-3700. I suspect what I'm actually dealing with is a TIMv0 that pre-dates the version used by Armada-3700. All the more reason to do something new instead of trying to shoe-horn it into one of the existing places. I'll probably end up making a fork of your mvebu64boot and adapting it (mox-imager just does too much).