[U-Boot] [RFC PATCH] ARM: Merge v7 and v8 outer cache operations

[Albert ARIBAUD]

Hello Mark,

On Thu, 12 Feb 2015 15:56:52 +0000, Mark Rutland <mark.rutland at arm.com>
wrote:
> On Sat, Jan 31, 2015 at 03:08:54AM +0000, fenghua at phytium.com.cn wrote:
> > From: David Feng <fenghua at phytium.com.cn>
> > 
> > Armv7 and Armv8 allow outer cache exist, it is outside of the architecture
> > defined cache hierarchy and can not be manipulated by architecture defined
> > instructions. It's processor specific.
> > This patch merge v7_outer_cache_* and v8 l3_cache_*.
> 
> This commit message is a little misleading, though it probably makes
> sense to have something of this sort ARMv8. Info dump below.
> 
> Recently the ARMv8 architecture reference manual was clarified to
> mention that any such system caches _must_ respect maintenance by VA,
> and are affected by the architected instructions for this. The arm64
> Linux port relies on this property.
> 
> Set/Way maintenance will not affect system caches. So if you want to
> flush/empty the entire cache hierarchy, you will need to rely on a
> mechanism specific to the outer cache implementation (rather than one
> specific to the processor).
> 
> Additionally, the interconnect and cache hierarchies in ARMv8
> implementations are becoming more complex, and it is more likely that
> dirty lines may migrate arbitrarily between CPUs and the system caches.
> Due to this you will need to ensure that CPU caches are disabled and
> empty before system cache maintenance is performed (I don't know whether
> your current sequences for ARMv7 ensure that).

So, does the commit message require rewriting?

> Thanks,
> Mark.

Amicalement,
-- 
Albert.