From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoffer Dall Subject: Re: [PATCH kvm-unit-tests 2/3] arm64: timer: Fix test on APM X-Gene Date: Fri, 14 Jul 2017 08:45:12 -0700 Message-ID: <20170714154512.GC1535@lvm> References: <20170713192009.10069-1-cdall@linaro.org> <20170713192009.10069-3-cdall@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Christoffer Dall , kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, Andrew Jones , Alexander Graf , Paolo Bonzini , Radim =?utf-8?B?S3LEjW3DocWZ?= , Jintack Lim To: Marc Zyngier Return-path: Received: from mail-lf0-f47.google.com ([209.85.215.47]:36412 "EHLO mail-lf0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753386AbdGNPpU (ORCPT ); Fri, 14 Jul 2017 11:45:20 -0400 Received: by mail-lf0-f47.google.com with SMTP id h22so55819220lfk.3 for ; Fri, 14 Jul 2017 08:45:19 -0700 (PDT) Content-Disposition: inline In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On Fri, Jul 14, 2017 at 09:04:10AM +0100, Marc Zyngier wrote: > On 13/07/17 20:20, Christoffer Dall wrote: > > When running the vtimer test on an APM X-Gene, setting the timer value > > to (2^64 - 1) apparently results in the timer always firing, even > > thought the counter is mich lower than the cval. > > Note that the system counter is only guaranteed to be at least 56 bit > wide (see DDI0487B.a G5.1.2), and I seem to remember that X-Gene only > has the minimum. This could explain why setting the comparator to a > value greater than (2^56 - 1) leads to a firing timer (the comparator > appears to be in the past). Thanks for pointing that out, that makes good sense. So then we should definitely fix the test. We could either set it to 2^56 - 1 instead, or just keep the 10s as used in this patch, because the whole test times out after 2s anyway. Thanks, -Christoffer