Hello Mark,
On Thu, 12 Feb 2015 15:56:52 +0000, Mark Rutland mark.rutland@arm.com wrote:
On Sat, Jan 31, 2015 at 03:08:54AM +0000, fenghua@phytium.com.cn wrote:
From: David Feng fenghua@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,