Oh my question contains discrepancy. My real question is whether the output of ioport_map is physical or virtual. (I'm confused) I know for systems with memory mapped I/O, we can just use request_mem_region, ioremap (maps to virtual address), plain memory access for the peripheral. (the page table sets the area as uncacheable because it's IO devices) Thanks! Chan Kim From: ckim@etri.re.kr <ckim@etri.re.kr> Sent: Monday, March 22, 2021 10:28 AM To: kernelnewbies@kernelnewbies.org Subject: question about ioport_map function Hello all
From what I understand, to map io ports to virtual memory, we should use request_region, ioport_map/unmap and ioread/write functions.
These are for architectures having input, output machine instructions like x86, x86_64. And the return address of ioport_map is physical address. Is my understanding correct? Thanks! Chan Kim