How to perform write back of dirty L1-L2 cache lines in ARMv8

Question

I'm looking for a way to flush the L1-L2 cache using a kernel module. Is there a way to completely flush the whole cluster cache (4 core configuration) or even better, write back the dirty cache lines into main memory?

Answer 1

It sounds weird that you want to flush your caches from a kernel module. That should be done by the core-kernel part and as a driver you should not have to worry about that.

Is there any specific reason you need to do that in a driver?

Answer 2

I think you want to have a look at 3.9 of "Understanding the Linux Virtual Memory Manager" [1] from Mel Gorman. I think what you are looking for is flush_cache_page(...)

[1] https://www.kernel.org/doc/gorman/

Answer 3

Well it seems that it is actually different the way that the caches are flushed in different architectures. Nevertheless, I didn't find an implementation that works. BUT, what I did was to find the Page table entry (PTE) of the particular page that I want to flush, and changed the memory attributes to Non-Cacheable. Then, the data went directly to the DRAM. (ARMv8) Cheers