Re: [PATCH v9 2/4] ring-buffer: Flush and stop persistent ring buffer on panic

[Mathieu Desnoyers]

On 2026-03-18 11:29, Masami Hiramatsu (Google) wrote:
> > - AFAIU, you are not trying to evince cache lines after creation
> >     of a new virtual mapping (which is the documented intent of
> >     flush_cache_vmap).
>
> Ah, OK. That's a good point!
> (anyway I will replace it with do { } while (0) in the next version.)
>
> >     
> > - AFAIU flush_cache_vmap maps to no-code on arm64 (asm-generic), what am
> >     I missing ? It makes sense to be a no-op because AFAIR arm64 does not
> >     have to deal with virtually aliasing caches.
>
> Yeah, so my patch also introduces arm64 specific implementation.

Just make sure to call this something else than "flush_cache_vmap",
because you don't want to slow down vmap on arm64 which does not
require to evince and certainly not write back cache lines after
creation of a new virtual mapping.

Thanks,

Mathieu

--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com