accessing a PCIe register from userspace through kmem or other ways ?

[Konstantin Belousov]

On Mon, Apr 04, 2016 at 09:02:49PM -0700, John Baldwin wrote:
> kib@ fixed /dev/mem to handle addresses beyond the direct map limit to use
> temporary mappings instead of failing with EFAULT in 277051 which was only
> committed to HEAD last January, so well after 8.2.

The mmap(2) interface to /dev/mem did not have the issue ever.  The problem
was only with the read(2)/write(2) accesses.

>From what I understand, since the goal of the OP was to measure BAR
access latencies, read(2) (or write) is unsuitable for him for obvious
reasons.