Does propeller supported in aarch64?

[hstk30-hw]

In propeller step 2, I see propeller dependce the LBR (last branch record) featue, which is deficienced in aarch64.

So does propeller supported in aarch64? Or can we do something let it work?
Maybe simulate the LBR feature by instrumentation in aarch64？

Thx.

[dhoekwater]

Yes, Propeller does support AArch64; while LBR isn't present on Arm, there are a number of different sources for hardware branch samples:

• Embedded Trace Macrocell (ETM)
• Statistical Profiling Extension (SPE)
• Branch Record Buffer Extension (BRBE)

Propeller tooling supports SPE, with some very rough documentation here. We plan to add support for ETM and BRBE in the next year or so.

While Propeller profile generation is mainly accessible through v0.30.1 of the AutoFDO repo, we're working on splitting out the Propeller codebase into this repo (hence the recent activity here); we expect to be done in the next few months.

[amharc]

FWIW, ETM and BRBE should be supported even as of now:

• BRBE walks and quacks like LBR in terms of what's in the perf.data files, so it should just work out of the box;
• ETM can be converted into something LBR-like using perf inject --itrace with appropriate params to --itrace (of particular importance is the l option, described in the manual as "synthesize last branch entries (use with i or x)")

We haven't tested those though (as opposed to SPE).