Re: [PATCH v1 0/6] tools/ocaml/xenstored: simplify code

From: Wei Liu <wl@xen.org>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Christian Lindig <christian.lindig@citrix.com>,
	Edwin Torok <edvin.torok@citrix.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	Ian Jackson <Ian.Jackson@citrix.com>,
	"dave@recoil.org" <dave@recoil.org>, "wl@xen.org" <wl@xen.org>
Subject: Re: [PATCH v1 0/6] tools/ocaml/xenstored: simplify code
Date: Thu, 27 Aug 2020 09:41:55 +0000	[thread overview]
Message-ID: <20200827094155.mrsghjnmjc72ab6q@liuwe-devbox-debian-v2> (raw)
In-Reply-To: <cd17508f-b170-3e3c-d8d3-26e827f7492a@citrix.com>

On Tue, Aug 18, 2020 at 01:40:18PM +0100, Andrew Cooper wrote:
> On 18/08/2020 10:25, Christian Lindig wrote:
> > I see little reason to support old OCaml releases and requiring OCaml 4.06 would be fine with me but I assume that the project might have its own ideas about this.
> >
> > ________________________________________
> > From: Edwin Torok
> > Sent: 18 August 2020 08:28
> > To: Christian Lindig; xen-devel@lists.xenproject.org
> > Cc: Ian Jackson; dave@recoil.org; wl@xen.org
> > Subject: Re: [PATCH v1 0/6] tools/ocaml/xenstored: simplify code
> >
> > On Mon, 2020-08-17 at 14:56 +0200, Christian Lindig wrote:
> >> This all looks good - I left a small comment on one of the patches
> >> and I agree that this needs testing. I also wonder about
> >> compatibility with earlier OCaml releases that we support but I see
> >> no real obstacles.
> >>
> > I've developed the series using OCaml 4.08.1. I think the newest
> > feature I used was Map.update (OCaml 4.06, nearly 3 years ago).
> > Looking through https://repology.org/project/ocaml/versions I'm not
> > sure if we can require more than 4.05 though.
> > The README in Xen doesn't specify a minimum version, but configure
> > checks for >=4.02.
> >
> > I can try to backport my series to OCaml 4.05 (to use Map.find_opt
> > instead of Map.update) and update the configure check to require 4.05.
> > It would be possible to backport even further to 4.02 by introducing
> > additional inefficiencies (Map.mem + Map.find would traverse the map
> > twice, and Map.find on its own would raise an exception on Not found,
> > which is more costly than returning None in Map.find_opt), I'd avoid
> > doing that.
> >
> > Xen's CI from automation might need some updates to use latest stable
> > versions:
> > * Fedora 29 is EOL, should use at least Fedora 31
> > * Debian Jessie is EOL. Stretch is present, but Buster is missing
> 
> We're working on the CI loop.
> 
> As maintainer, it is ultimately Christian's choice to as to if/when to
> bump the minimum versions.
> 
> 
> As a general rule, we don't want to be sufficiently bleeding edge to
> rule out in-use distros.  I have no idea if 4.06 is ok there, or whether
> it is too new.  Then again, the Ocaml components are strictly optional
> so it is perhaps less important.
> 
> Whatever happens WRT version, the configure change should occur before
> changes in the code which would fail on older versions.

Yes I would like to see the bump happen before applying a version of
this series too.

Wei.

> 
> ~Andrew