Timeline for 2.13 SOF release

[kv2019i]

Checklist for 2.13 created today with proposed dates for a May release:
#9863

May 2025 follows the target cadence agreed in SOF TSC, where SOF is following the 4-month cadence of Zephyr https://github.com/zephyrproject-rtos/zephyr/wiki/Release-Management so that SOF release is 2 months after Zephyr release (e.g. Zephyr 4.1 release target is March 2025).

Note: at this point, only the release timeline is aligned. SOF does not sync the Zephyr code version to a Zephyr release tag, but instead a commit from Zephyr main is used as a basis of the release. For example SOF2.12 release uses a snapshot of Zephyr main taken in December during v4.1 development cycle.

[kv2019i]

FYI to @thesofproject/steering-committee

[lgirdwood]

@kv2019i snapshot on top of latest Zephyr release should be targeted, unless we are still in the position of WIP drivers/infra still being upstreamed (which I think will still probably be true).

[kv2019i]

@lgirdwood I think we've reached a stable state w.r.t. SOF infra, so I don't think that should be a blocker anymore. There are new drivers added to Zephyr, but I think this is more a business as usual thing.

I think it's more of a question deciding to do it. This will require SOF developers to be more aware of Zephyr release timelines (e.g. Feb 7 feature freeze for 4.1), but I think this is reasonable.
In SOF, we need to decide whether we accept a partial freeze of main as we fix Zephyr version in SOF mainline prior to rc1 tag, or do we pull SOF release closer to Zephyr release . Using 2.13 timeline as example:

• March 7th -> ETA for Zephyr 4.1
• May 5th -> ETA for SOF stable-v2.13 branch

In the past we've not locked SOF main at all during the release window. If we want to lock SOF main to Zephyr 4.1, we either have a lock period in SOF main (Zephyr version cannot be updated until we branch rc1/stable-v2.13), or we pull in the SOF release sooner, and branch rc1 out as soon as we have a Zephyr release and SOF testing passes with the new version.

Locking Zephyr version is potentially problematic as there's usually a flurry of activity in Zephyr main after a release, and we want to keep ability to track latest changes of Zephyr in SOF main and catch regressions early.

Other option is to keep to the current rolling method where we honor the ebb and flow of Zephyr release cycle, but keep SOF main open to updates throughout the cycle. I believe this is also used by may Zephyr downstream users.

[lgirdwood]

Lets keep the rolling method until integration is more complete for all platforms.