Re: Oldest supported Xen version in upstream QEMU (Was: Re: [Minios-devel] [PATCH v2 0/15+5+5] Begin to disentangle libxenctrl and provide some stable libraries)

From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Juergen Gross <jgross@suse.com>
Cc: Wei Liu <wei.liu2@citrix.com>,
	Ian Campbell <ian.campbell@citrix.com>,
	Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
	Ian Jackson <Ian.Jackson@eu.citrix.com>,
	xen-devel <xen-devel@lists.xen.org>,
	Roger Pau Monne <roger.pau@citrix.com>
Subject: Re: Oldest supported Xen version in upstream QEMU (Was: Re: [Minios-devel] [PATCH v2 0/15+5+5] Begin to disentangle libxenctrl and provide some stable libraries)
Date: Wed, 23 Sep 2015 10:21:34 -0400	[thread overview]
Message-ID: <20150923142133.GF2569@konrad-lan.dumpdata.com> (raw)
In-Reply-To: <5602B461.9010507@suse.com>

On Wed, Sep 23, 2015 at 04:17:05PM +0200, Juergen Gross wrote:
> On 09/23/2015 04:09 PM, Konrad Rzeszutek Wilk wrote:
> >On Wed, Sep 23, 2015 at 09:29:10AM +0100, Ian Campbell wrote:
> >>On Tue, 2015-09-22 at 22:31 +0100, Stefano Stabellini wrote:
> >>>The oldest Xen version I build-test for every pull request is Xen 4.0.0,
> >>>I think it is very reasonable to remove anything older than that.
> >>>I am OK with removing Xen 4.0.0 too, but I would like a warning to be
> >>>sent ahead of time to qemu-devel to see if anybody complains.
> >>
> >>There is not much point in removing <=3.4 support and keeping 4.0, since
> >>4.0.0 was the last one which used a plain int as a handle, anything older
> >>than 4.0.0 is trivial if 4.0.0 is supported.
> >>
> >>One approach I am considering in order to keep 4.0.0 support and earlier
> >>was to turn the "int fd" for <=4.0 into a pointer by having the open
> >>wrapper do malloc(sizeof int) and the using wrappers do xc_foo(*handle).
> >>
> >>This way all the different variants take pointers and we have less hoops to
> >>jump through to typedef everything in the correct way for each variant.
> >>
> >>If you would rather avoid doing that then I think dropping 4.0.0 support
> >>would be the way to go and I'll send a mail to qemu-devel.
> >
> >Perhaps to help in killing the 4.0.0 support - Linux pvops can't work
> >with Xen 4.0.0 - sadly I don't recall the details but I think it was missing
> >an hypercall.
> 
> Are you sure? On the Xen developer summit this year I asked a guy from

And I am incorrect (from http://wiki.xen.org/wiki/Dom0_Kernels_for_Xen):

	"Q: I've seen mentions of 'pv_ops' and 'xenlinux' kernels. Which one
	should I choose?

	Simple answer: pv_ops. Xen Project 4.0 switched to using Linux pv_ops
	based dom0 kernel as a default.."

> Amazon whether they are testing upstream pvops kernels on all Xen
> versions they support, and he confirmed that. And they do support Xen
> 4.0 and older.

Oh gosh, older than 4.0? Ugh.

> 
> 
> Juergen
> 