rtos: alloc: Fix SOF_MEM_FLAG_* values

[dbaluta]

Commit 5821682 ("heap: simplify heap API") changed the heap API to make it more like Linux kernel API.

For example:
-> rballoc_align(flags, caps, bytes, align)

transformed into:

-> rballoc_align(flags, bytes, align)

So, caps was merged into flags! Causing overrun_permitted to be set and making a lots of test (e.g SRC, Compress) to fail.

The original flags were the SOF_BUF_ flags mostly sent from Linux and read from topology (e.g SOF_BUF_OVERRUN_PERMITTED, SOF_BUF_UNDERRUN_PERMITTED).

But the new flags SOF_MEM_FLAG_* did not take this into account and overlap with the older flags.

For now, what we can do is just shift the new flags so that they do not overlap with the old flags.

[dbaluta]

@lgirdwood this is not an ideal fix, but it really unblocks lots of failed tests on IMX side.

[Copilot]

Pull Request Overview

This PR fixes SOF_MEM_FLAG_* values to prevent overlap with existing SOF_BUF_* flags after a recent API change that merged capabilities into flags. The fix ensures compatibility by reserving the first two bit positions for SOF_BUF_* flags and shifting SOF_MEM_FLAG_* values to higher bit positions.

• Adds comments explaining the compatibility requirement and reserved bit positions
• Shifts all SOF_MEM_FLAG_* definitions to higher bit values to avoid overlap
• Updates both Zephyr and POSIX implementations consistently

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
zephyr/include/rtos/alloc.h	Shifts SOF_MEM_FLAG_* values starting from BIT(1) with reserved positions for compatibility
posix/include/rtos/alloc.h	Shifts SOF_MEM_FLAG_* values starting from BIT(2) with reserved positions for compatibility

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[lgirdwood]

@dbaluta think it may just be better removing the audio_stream->underrun_permitted as it looks like no one is using them in topology and no one is using the DMA based scheduling. Pls do shout if anyone is using.

[lgirdwood]

ok, looks like we need to split out the caps for buffers a tad more.
So @jsarha is working on removing rballoc() to align with a single low level allocator and we need some way for buffer API to handle.
@dbaluta btw - I dont think we have any users of the SOF_BUF_OVERRUN_PERMITTED and SOF_BUF_UNDERRUN_PERMITTED - at least from grepping the topologies - IIRC these were a legacy flag around DMA based scheduling of pipelines (where > 1 DMAs could trigger at the same time). I think we could remove.

[dbaluta]

@lgirdwood I think this is a slightly better PR: #10228

with less invasive modification.

[dbaluta]

@dbaluta think it may just be better removing the audio_stream->underrun_permitted as it looks like no one is using them in topology and no one is using the DMA based scheduling. Pls do shout if anyone is using.

I prefer not to remove this as it looks very invasive. Lots of bad things could happen.

Instead I have fixed the issue of modified flags here: #10228

[kv2019i]

I'm good with this as well.