question about ioport_map function

[ckim at etri.re.kr]

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 at etri.re.kr <ckim at etri.re.kr> 
Sent: Monday, March 22, 2021 10:28 AM
To: kernelnewbies at 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

 

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