On 19/09/2023 15:36, Volodymyr Babchuk wrote:
Julien Grall <jul...@xen.org> writes:
On 19/09/2023 12:28, Volodymyr Babchuk wrote:
There is no need to invalidate cache entry because we just wrote into a
memory region. Writing itself guarantees that cache entry is valid.
The goal of invalidate is to remove the line from the cache. So I
don't quite understand the reasoning here.
Well, I may be wrong, but what is the goal in removing line from the
cache? As I see this, we want to be sure that ITS sees data written in
the memory, so we should flush a cache line. But why do we need to
remove it from CPU's cache?
I don't exactly know. From a brief look I agree with you. However, our
driver is based on Linux where the clean & invalidate is also used. So I
am a little be cautious to remove it.
The way forward would be to ask the Marc Zyngier (GICv3 maintainer) why
it was added in Linux. Then we can decide whether this can be removed in
Xen.
Cheers,
--
Julien Grall
