From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: KVM call minutes for Feb 1 Date: Tue, 01 Feb 2011 11:20:14 -0600 Message-ID: <4D4840CE.5020700@codemonkey.ws> References: <20110201155414.GF28968@x200.localdomain> <4D48367D.2060802@siemens.com> <4D483A9B.9000205@codemonkey.ws> <4D483CCF.60009@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Chris Wright , "kvm@vger.kernel.org" , "qemu-devel@nongnu.org" To: Jan Kiszka Return-path: Received: from mail-qw0-f46.google.com ([209.85.216.46]:60581 "EHLO mail-qw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755605Ab1BARUS (ORCPT ); Tue, 1 Feb 2011 12:20:18 -0500 Received: by qwa26 with SMTP id 26so6924584qwa.19 for ; Tue, 01 Feb 2011 09:20:17 -0800 (PST) In-Reply-To: <4D483CCF.60009@siemens.com> Sender: kvm-owner@vger.kernel.org List-ID: On 02/01/2011 11:03 AM, Jan Kiszka wrote: > On 2011-02-01 17:53, Anthony Liguori wrote: > >> On 02/01/2011 10:36 AM, Jan Kiszka wrote: >> >>> On 2011-02-01 16:54, Chris Wright wrote: >>> >>> >>>> KVM upstream merge: status, plans, coordination >>>> - Jan has a git tree, consolidating >>>> - qemu-kvm io threading is still an issue >>>> - Anthony wants to just merge >>>> - concerns with non-x86 arch and merge >>>> - concerns with big-bang patch merge and following stability >>>> - post 0.14 conversion to glib mainloop, non-upstreamed qemu-kvm will be >>>> a problem if it's not there by then >>>> - testing and nuances are still an issue (e.g. stefan berger's mmio read issue) >>>> - qemu-kvm still evolving, needs to get sync'd or it will keep diverging >>>> - 2 implementations of main init, cpu init, Jan has merged them into one >>>> - qemu-kvm-x86.c file that's only a few hundred lines >>>> - review as one patch to see the fundamental difference >>>> >>>> >>> More precisely, my current work flow is to pick some function(s), e.g. >>> kvm_cpu_exec/kvm_run, and start wondering "What needs to be done to >>> upstream so that qemu-kvm could use that implementation?". If they >>> differ, the reasons need to be understood and patched away, either by >>> fixing/enhancing upstream or simplifying qemu-kvm. Once the upstream >>> changes are merged back, a qemu-kvm patch is posted to switch to that >>> version. >>> >>> Any help will be welcome, either via review of my subtle regressions or >>> on resolving concrete differences. >>> >>> E.g. posix-aio-compat.c: Why does qemu-kvm differ here? If it's because >>> of its own iothread code, can we wrap that away or do we need to >>> consolidate the threading code first? Or do we need to fix something in >>> upstream? >>> >>> >> I bet it's the eventfd thing. It's arbitrary. If you've got a small >> diff post your series, I'd be happy to take a look at it and see what I >> can explain. >> >> > Looks like it's around signalfd and its emulation: > I really meant the compatfd thing. signalfd can't really be emulated properly so in upstream we switched to a pipe() which Avi didn't like. But with glib, this all goes away anyway so we should just drop the qemu-kvm changes and use the upstream version. Once we enable I/O thread in qemu.git, we no longer need to use signals for I/O completion which I think everyone would agree is a better solution. Regards, Anthony Liguori