Date: Sat, 1 Mar 2008 01:50:02 GMT From: linimon@lonesome.com (Mark Linimon) To: freebsd-acpi@FreeBSD.org Subject: Re: kern/112544: [acpi] [patch] Add High Precision Event Timer Driver for userland timer facility Message-ID: <200803010150.m211o2p2011913@freefall.freebsd.org>
next in thread | raw e-mail | index | archive | help
The following reply was made to PR kern/112544; it has been noted by GNATS. From: linimon@lonesome.com (Mark Linimon) To: bug-followup@FreeBSD.org Cc: Subject: Re: kern/112544: [acpi] [patch] Add High Precision Event Timer Driver for userland timer facility Date: Fri, 29 Feb 2008 19:41:46 -0600 ----- Forwarded message from John Baldwin <jhb@freebsd.org> ----- The HPET contains multiple bits. One is a general count down timer that we use for timekeeping. In addition it contains a variable number of comparator registers each of which can be used to generate interrupts at varying frequencies (or one-shot interrupts, etc.). The current in-kernel HPET support only handles the count down timer. We do not have any support for the comparators. The code in the PR does include support for the comparators. However, it's aim is to export them for use by userland drivers. FreeBSD will probably end up using the HPET comparators to back deadline-style clock interrupts in place of the RTC or lapic timer at some point in which case certain pieces of this code may be useful. The commit I made just extracted a few of the changes in the original patch, it did not contain all of the changes in the patch. It is probably best to mark this as suspended and leave it as freebsd-acpi@ for now as I'm not currently planning on doing the deadline clock stuff. -- John Baldwin ----- End forwarded message -----
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200803010150.m211o2p2011913>