From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:34252 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726513AbgEOHL7 (ORCPT ); Fri, 15 May 2020 03:11:59 -0400 Subject: Re: [kvm-unit-tests PATCH v6 07/10] s390x: css: msch, enable test References: <1587725152-25569-1-git-send-email-pmorel@linux.ibm.com> <1587725152-25569-8-git-send-email-pmorel@linux.ibm.com> <20200514140808.269f6485.cohuck@redhat.com> From: Pierre Morel Message-ID: Date: Fri, 15 May 2020 09:11:52 +0200 MIME-Version: 1.0 In-Reply-To: <20200514140808.269f6485.cohuck@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-s390-owner@vger.kernel.org List-ID: To: Cornelia Huck Cc: Janosch Frank , kvm@vger.kernel.org, linux-s390@vger.kernel.org, david@redhat.com, thuth@redhat.com On 2020-05-14 14:08, Cornelia Huck wrote: > On Tue, 28 Apr 2020 10:27:36 +0200 > Pierre Morel wrote: > >> On 2020-04-27 15:11, Janosch Frank wrote: >>> On 4/24/20 12:45 PM, Pierre Morel wrote: > >>>> This is NOT a routine to really enable the channel, no retry is done, >>>> in case of error, a report is made. >>> >>> Would we expect needing retries for the pong device? >> >> Yes it can be that we need to retry some instructions if we want them to >> succeed. >> This is the case for example if we develop a driver for an operating system. >> When working with firmware, sometime, things do not work at the first >> time. Mostly due to races in silicium, firmware or hypervisor or between >> them all. >> >> Since our purpose is to detect such problems we do not retry >> instructions but report the error. >> >> If we detect such problem we may in the future enhance the tests. > > I think I've seen retries needed on z/VM in the past; do you know if > that still happens? > I did not try the tests under z/VM, nor direct on an LPAR, only under QEMU/KVM. Under QEMU/KVM, I did not encounter any need for retry, 100% of the enabled succeeded on first try. Regards, Pierre -- Pierre Morel IBM Lab Boeblingen