Re: icache_is_aliasing and big.LITTLE

From: Catalin Marinas
Date: Thu May 09 2019 - 04:51:21 EST


On Wed, May 08, 2019 at 11:45:03AM -0700, Salman Qazi wrote:
> What is the intention behind icache_is_aliasing on big.LITTLE systems
> where some icaches are VIPT and others are PIPT? Is it meant to be
> conservative in some sense or should it be made per-CPU?

It needs to cover the worst case scenario across all CPUs, i.e. aliasing
VIPT if one of the CPUs has this. We can't make it per-CPU because a
thread performing cache maintenance might be migrated to another CPU
with different cache policy (e.g. sync_icache_aliases()).