From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id 84CA4DDFD4 for ; Fri, 12 Oct 2007 00:12:28 +1000 (EST) In-Reply-To: <18190.3365.54961.935346@cargo.ozlabs.ibm.com> References: <18190.3365.54961.935346@cargo.ozlabs.ibm.com> Mime-Version: 1.0 (Apple Message framework v752.2) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: <96C1AFB8-784F-445E-A3F2-5D68494541CD@kernel.crashing.org> From: Kumar Gala Subject: Re: [PATCH] Make clockevents work on PPC601 processors Date: Thu, 11 Oct 2007 09:12:49 -0500 To: Paul Mackerras Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Oct 11, 2007, at 6:46 AM, Paul Mackerras wrote: > In testing the new clocksource and clockevent code on a PPC601 > processor, I discovered that the clockevent multiplier value for the > decrementer clockevent was overflowing. Because the RTCL register in > the 601 effectively counts at 1GHz (it doesn't actually, but it > increases by 128 every 128ns), and the shift value was 32, that meant > the multiplier value had to be 2^32, which won't fit in an unsigned > long on 32-bit. The same problem would arise on any platform where > the timebase frequency was 1GHz or more (not that we actually have any > such machines today). do you still have a 601 running somewhere? - k