Re: [Xen-devel] Xen 4.5 development update (September update). Feature freeze slip by two weeks.

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Tue, Oct 07, 2014 at 12:48:27PM +0000, Dave Scott wrote:
> Hi Konrad,
> 
> On 25 Sep 2014, at 22:26, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> 
> wrote:
> 
> > On Thu, Sep 25, 2014 at 10:25:42AM +0100, George Dunlap wrote:
> >> On 09/25/2014 10:22 AM, Dave Scott wrote:
> >>> Hi Konrad,
> >>> 
> >>> On 10 Sep 2014, at 18:05, <konrad.wilk@xxxxxxxxxx> 
> >>> <konrad.wilk@xxxxxxxxxx> wrote:
> >>> 
> >>>> *  extend the xenstore ring with a 'closing' signal (fair)
> >>>>  RFC patch posted
> >>>> -  David Scott
> >>> Iâd like to propose an exception for this one. The title is perhaps 
> >>> underselling it: although it is a protocol extension (and hence a new 
> >>> feature) the main motivation is to fix a bug in hvmloader which causes 
> >>> HVM guests to hang during booting on a busy machine. The bug is fairly 
> >>> easy to reproduce with ~200 VMs: youâll probably find at least one failed 
> >>> to boot.
> >>> 
> >>> The patch set has got to a v4 but needs a little bit of work to clarify 
> >>> the relationship between the closing signal and the existing 
> >>> RESET_WATCHES xenstore protocol request.
> > 
> > It looked (from a brief look) as it has OCaml and I have no experience
> > with that. Is there somebody who can review it?
> > 
> > I hadn't dug in it to give it yet an opinion (sorry).
> 
> Iâve managed to gather an Acked-by from IanJ (NB without reviewing the OCaml 
> parts):
> 
> http://lists.xenproject.org/archives/html/xen-devel/2014-09/msg04255.html

<nods>
> 
> On 26 Sep 2014, at 15:00, Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx> wrote:
> 
> > Acked-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> > 
> > I'm happy to take this from you without really reviewing the ocaml
> > code.
> 
> 
> and Iâve got a positive review from Jon Ludlam (an OCaml expert)[added to 
> cc:] just now on the OCaml parts:
> 
> http://lists.xenproject.org/archives/html/xen-devel/2014-10/msg00748.html
> 
> On 7 Oct 2014, at 12:26, Jon Ludlam <jonathan.ludlam@xxxxxxxxxxxxx> wrote:
> 
> > Handling the exception higher up looks a fair bit nicer, and my previous
> > comment has been addressed, so it looks fine to me.
> > 
> > Reviewed-by: Jon Ludlam <jonathan.ludlam@xxxxxxxxxx>
> 
> FWIW I think this is still worth taking for 4.5 because
> 
> 1. it fixes a real bug (HVM VMs occasionally failing to boot because of bad 
> hvmloader/xenstored interaction)
> 
> 2. the oxenstored changes are quite unobtrusive: the flag is sampled at the 
> bottom, an exception bubbles all the way (almost) to the top and is handled 
> there. If something were to go wrong, that exception would be caught at the 
> main loop allowing the process to continue.
> 
> What do you think?

I concur.

Release-Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

> 
> Cheers,
> Dave
> 

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