From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:54979) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gt9e3-0006YO-7O for qemu-devel@nongnu.org; Mon, 11 Feb 2019 06:21:04 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gt9e1-0000OB-5d for qemu-devel@nongnu.org; Mon, 11 Feb 2019 06:21:03 -0500 Date: Mon, 11 Feb 2019 12:20:56 +0100 From: Cornelia Huck Message-ID: <20190211122056.24ce395a.cohuck@redhat.com> In-Reply-To: <025ce67d-f39e-b44b-8606-647f8695cbe5@redhat.com> References: <1548956828-10210-1-git-send-email-thuth@redhat.com> <20190131185621.28815291.cohuck@redhat.com> <538ee62b-293d-f053-4bd2-76bf166388e1@redhat.com> <20190201092356.295925c2.cohuck@redhat.com> <20190211114859.76109aa3.cohuck@redhat.com> <746bc346-26ce-e096-d8a4-fe78bf7912c1@redhat.com> <20190211120432.42373d08.cohuck@redhat.com> <025ce67d-f39e-b44b-8606-647f8695cbe5@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] hw/s390x: Fix the function arguments in the pci stub file List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Thomas Huth Cc: Paolo Bonzini , qemu-s390x@nongnu.org, Collin Walling , qemu-devel@nongnu.org On Mon, 11 Feb 2019 12:17:26 +0100 Thomas Huth wrote: > On 2019-02-11 12:04, Cornelia Huck wrote: > > On Mon, 11 Feb 2019 11:54:45 +0100 > > Thomas Huth wrote: > > > >> On 2019-02-11 11:48, Cornelia Huck wrote: > >>> On Fri, 1 Feb 2019 09:23:56 +0100 > >>> Cornelia Huck wrote: > >>> > >>>> On Fri, 1 Feb 2019 07:46:40 +0100 > >>>> Thomas Huth wrote: > >>> > >>>>> So I see two options now: > >>>>> > >>>>> 1) Finally really make the device optional, at least for new machine > >>>>> types, so we can really disable CONFIG_PCI and get a working executable. > >>>>> > >>>>> 2) Scratch the idea completely to make this optional, always link the > >>>>> s390-pci-bus.o and s390-pci-inst.o files unconditionally, and remove the > >>>>> s390-pci-stub.c file. > >>>>> > >>>>> I assume options 2 is preferred, since we likely rather want to move > >>>>> into the PCI direction in the long run, instead of ignoring it... > >>>> > >>>> I think both options are viable, but option 1 is of course more work. > >>>> The win there is that we could disable an entire subsystem. > >>>> > >>>> I guess that the basic questions are: How important is it that > >>>> subsystems can be compiled out, and do we see a use case for a pci-less > >>>> s390 machine in the future? We really don't want to spend much time on > >>>> something of dubious use... > >>> > >>> Any thoughts on this? > >>> > >>> I'm currently tending towards option 2 (and can cook up a patch for > >>> that). Unless someone is already working on option 1 :) > >> > >> Since nobody currently has a need to completely disable PCI, I think we > >> should go with option 2. > > > > Hm... I'm wondering if we also should move S390_FEAT_ZPCI from the max > > cpu model to the qemu cpu model (is there any reason not to turn it on > > by default in tcg?) > > Migration compatibility? Wouldn't that cause problems when migrating > back to older versions of QEMU? Not sure. But we can still do that in a follow-on patch, if wanted.