Queries on pci address-ranges

[Ajay Garg <ajaygargnsit@xxxxxxxxx>]

Hi everyone.

I had written a (hello-world) PCI-driver couple of years back, and was
able to read/write from/to BARs.
I might have a requirement of writing more drivers, so was revisiting
the concepts.

I have some queries (we can assume no IOMMU is in the picture) :

0.
Assertion : During PCI-enumeration, the physical-memory assigned to a
BAR is always contiguous. (Yes/No)?

1.
During ioremap() of BAR-physical memory, does the (mapped)
kernel-virtual-memory correspond to

             * one used in vmalloc(), wherein the
kernel-virtual-address => physical-address
               goes through page-tables?
             * one used in kmalloc(), wherein the
kernel-virtual-address => physical-address
               *in all likelihood* requires only adding an offset?

2.
On a related front, how does ioremap() differ from kmap()?


Will be grateful for your time.


Thanks and Regards,
Ajay