svn commit: r273598 - in head: include sys/dev/acpica

[Rui Paulo]

On Oct 24, 2014, at 12:06 PM, Andriy Gapon <avg at FreeBSD.org> wrote:

On 24/10/2014 21:39, Rui Paulo wrote:
> Author: rpaulo
> Date: Fri Oct 24 18:39:15 2014
> New Revision: 273598
> URL: https://svnweb.freebsd.org/changeset/base/273598
> 
> Log:
> HPET: create /dev/hpetN as a way to access HPET from userland.
> 
> In some cases, TSC is broken and special applications might benefit
> from memory mapping HPET and reading the registers to count time.
> Most often the main HPET counter is 32-bit only[1], so this only gives
> the application a 300 second window based on the default HPET
> interval.
> Other applications, such as Intel's DPDK, expect /dev/hpet to be
> present and use it to count time as well.

Does this device attempt to play nice with eventtimer infrastructure that may
use the same timer?
 
No.  That's up to the userland applications and that's why I implemented the read-only restriction.