From: "Lee Revell" <rlrevell@joe-job.com>
To: Raz <raziebe@gmail.com>
Cc: "Linux Kernel" <linux-kernel@vger.kernel.org>
Subject: Re: mmap over HPET - 32 bit wrap arround
Date: Wed, 28 May 2008 19:57:11 -0400 [thread overview]
Message-ID: <75b66ecd0805281657k7b988bf1qa46e806810da0c17@mail.gmail.com> (raw)
In-Reply-To: <5d96567b0805281519v7ee18eb0l27f2e4edc18af01c@mail.gmail.com>
On Wed, May 28, 2008 at 6:19 PM, Raz <raziebe@gmail.com> wrote:
> I am wondering wether someone can explain how hpet behaves. The bellow
> is a short program that reads from a mmaped /dev/hpet the time. I am
> running it and it looks that afer ~296 seconds the counter resets . I
> AM RUNNING 64bi KERNEL(2.6.18-8.el5) and reading a 64BIT VARIABLE.
> my hpet is 14MHZ, so I am guessing a 32bit wraparound ( ~296 * 14Mhz
> ) = MAX_INT . but why ?
>
HPET counter can be either 32 or 64 bit. Check COUNT_SIZE_CAP.
http://www.intel.com/hardwaredesign/hpetspec_1.pdf
Lee
next prev parent reply other threads:[~2008-05-28 23:57 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <83CA05F64804AF43B8F733C4ABDFAA5101384F73@mail1.bitband.com>
[not found] ` <83CA05F64804AF43B8F733C4ABDFAA5101384FA4@mail1.bitband.com>
2008-05-28 22:19 ` Raz
2008-05-28 23:57 ` Lee Revell [this message]
2008-05-31 18:20 ` Raz
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