Re: device driver for the SGI system clock, mmtimer

From: Bjorn Helgaas (bjorn.helgaas_at_hp.com)
Date: 09/16/04

  • Next message: Utz Lehmann: "[PATCH] flexmmap: optimise mmap_base gap for hard limited stack" 
    To: Christoph Lameter <clameter@sgi.com>
Date:	Thu, 16 Sep 2004 10:54:51 -0600

    On Thursday 16 September 2004 10:32 am, Christoph Lameter wrote:
    > On Thu, 16 Sep 2004, Bjorn Helgaas wrote:
    > > Christoph Lameter wrote:
    > > > The timer hardware was designed around the multimedia timer specification by Intel
    > > > but to my knowledge only SGI has implemented that standard. The driver was written
    > > > by Jesse Barnes.
    > >
    > > As far as I can see, drivers/char/hpet.c talks to the same hardware.
    > > HP sx1000 machines (and probably others) also implement the HPET.
    >
    > The Intel Multimedia Standard is a earlier and different timer spec.

    I have a spec that's labelled "IA-PC Multimedia Timers", preliminary
    draft of June 2000, revision 0.97, which looks like the one mentioned
    in your patch.

    I also have something labelled "IA-PC HPET (High Precision Event
    Timers) Specification", draft of February 2002, revision 0.98,
    which is what drivers/char/hpet.c supports.

    I admit I haven't compared them in great detail, but they certainly
    *look* like they're close enough that the same driver could support
    both, and the 0.98 revision history only mentions fairly cosmetic
    changes (like the name :)).

    Is there something specific that drivers/char/hpet.c expects that
    your hardware doesn't implement?
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

  • Next message: Utz Lehmann: "[PATCH] flexmmap: optimise mmap_base gap for hard limited stack"

    Relevant Pages

    • Re: [PATCH] i386: Selectable Frequency of the Timer Interrupt
      ... and nobody from the latency ... 250/300 seems like a reasonable comprimise to me. ... *does* it cause (in visible effect, not "timers are less granular"). ... send the line "unsubscribe linux-kernel" in ...
      (Linux-Kernel)
    • Re: [ANNOUNCE] ktimers subsystem
      ... These timers may open up new ... > application (in kernel or user space), ... Tim Bird ... send the line "unsubscribe linux-kernel" in ...
      (Linux-Kernel)
    • Re: [ANNOUNCE] ktimers subsystem
      ... These timers may open up new ... > degradation for ANY app on ANY platform? ... send the line "unsubscribe linux-kernel" in ...
      (Linux-Kernel)
    • Timers to threads
      ... We are using Linux in one of our embedded products.This is the first time we are working in this Platform.We have few doubts regarding implementing s/w timers & how to pass the timer interrupts to threads. ... If we use kernel timers to invoke at particular time intervals using add_timer how to pass on to the application that the time has elapsed? ... Embedded Systems & Software ... send the line "unsubscribe linux-kernel" in ...
      (Linux-Kernel)
    • Re: [PATCH] i386: Selectable Frequency of the Timer Interrupt
      ... >> That's a very subjective viewpoint. ... We have had complaints about repeating timers not keeping good time. ... expected frequency. ... send the line "unsubscribe linux-kernel" in ...
      (Linux-Kernel)