From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zachary Amsden Subject: Re: [PATCH 17/17] Add timekeeping documentation Date: Wed, 16 Jun 2010 13:59:44 -1000 Message-ID: <4C196570.5080803@redhat.com> References: <1276587259-32319-1-git-send-email-zamsden@redhat.com> <1276587259-32319-18-git-send-email-zamsden@redhat.com> <20100615132755.9b8d9041.randy.dunlap@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: avi@redhat.com, mtosatti@redhat.com, glommer@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org To: Randy Dunlap Return-path: In-Reply-To: <20100615132755.9b8d9041.randy.dunlap@oracle.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 06/15/2010 10:27 AM, Randy Dunlap wrote: > On Mon, 14 Jun 2010 21:34:19 -1000 Zachary Amsden wrote: > > >> Basic informational document about x86 timekeeping and how KVM >> is affected. >> > Nice job/information. Thanks. > > Just some typos etc. inline below. > Thanks for all the detailed feedback! I'll include it all in the next revision. I only have one response: > >> + low, the count is halted. If the output is low when the gate is lowered, the >> + output automatically goes high (this only affects timer 2). >> + >> +Mode 3: Square Wave. This generates a sine wave. The count determines the >> > a sine wave is a square wave??? > Actually, yes. The hardware output from timer 2 output goes through a low pass filter which effectively smooths the square wave to a sine to make the PC speaker sound somewhat less annoying. I didn't have room to depict this in the schematic. Of course, the counter output isn't directly a sine wave, and the LPF may not be all that effective, but it was the intent. Zach