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From: George Dunlap <george.dunlap@citrix.com>
To: Ian Jackson <Ian.Jackson@eu.citrix.com>, Olaf Hering <olaf@aepfle.de>
Cc: Anthony Perard <anthony.perard@citrix.com>,
	Wei Liu <Wei.Liu2@citrix.com>,
	"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>
Subject: Re: 4.7 qemu regression: HVM guests fail to boot from xvda
Date: Wed, 8 Jun 2016 11:23:47 +0100	[thread overview]
Message-ID: <5757F233.6050500@citrix.com> (raw)
In-Reply-To: <22359.61702.816424.279071@mariner.uk.xensource.com>

On 08/06/16 11:18, Ian Jackson wrote:
> Olaf Hering writes ("Re: [Xen-devel] 4.7 qemu regression: HVM guests fail to boot from xvda"):
>> To achieve this the default hdtype= should become "UNSET", and a vdev=hd
>> should set it to IDE if it was "UNSET". That means there could be yet
>> another state "PVONLY".
> 
> I'm afraid I think this way lies madness.  You are suggesting that the
> default for hdtype= should depend in a complicated way on the set of
> disk vdevs.  (It also makes hotplug very confusing.)
> 
>>> The possibilities I see are:
>>>
>>> (1) New boolean per-guest parameter for this behaviour, meaning
>>>    `provide emulated devices for all xvd* as if they were hd*'.
>>
>> This would be an backward compatible approach, at least domU.cfg will
>> work with older toolstack. libvirt needs to know about this.
> 
> This is a strange use of the phrase "backward compatible".  What you
> mean is that the necessary domU.cfg changes are backward compatible.
> 
>>> What should happen if these options are enabled for PV guests - should
>>> they be silently ignored, or should they be rejected ?
>>
>> IMO no. Do we have such rejects already for PV or HVM only options?
> 
> Maybe.
> 
>> It has to be noted that libvirt does not seem to know about the hdtype=
>> knob, which was introduced in xen-4.6.
> 
> Anyway, to conclude: it seems that you don't like any of my other
> options.  I don't like your suggestion.  But you seem happy with my
> option (1), above.
> 
> Personally I prefer George's suggestion:
>   What about a per-disk property, emulate={default,always,only}

We could consider at an xl level having a domain-wide and system-wide
defaults.  That way Olaf could set "disk_emulate_default=always" (or
whatever) in the global xl.conf and everything would work the way it
used to without even needing to change individual guest config files.

 -George

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  reply	other threads:[~2016-06-08 10:23 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-30 20:42 4.7 qemu regression: HVM guests fail to boot from xvda Olaf Hering
2016-05-31 11:02 ` George Dunlap
2016-05-31 11:16   ` Olaf Hering
2016-05-31 11:32     ` George Dunlap
2016-05-31 11:41       ` Olaf Hering
2016-05-31 12:00         ` George Dunlap
2016-05-31 12:04           ` Olaf Hering
2016-06-01 13:17             ` Olaf Hering
2016-06-01 21:40               ` Olaf Hering
2016-06-02 11:49                 ` Wei Liu
2016-06-02 12:06                   ` Olaf Hering
2016-05-31 12:15           ` Jan Beulich
2016-06-01  9:48           ` Wei Liu
2016-06-01 13:34             ` Olaf Hering
2016-06-01 14:11               ` Wei Liu
2016-06-01 14:32                 ` Olaf Hering
2016-06-01 15:36           ` Ian Jackson
2016-06-03 10:13             ` George Dunlap
2016-06-03 11:20               ` Olaf Hering
2016-06-03 11:27                 ` George Dunlap
2016-06-03 11:45                   ` Ian Jackson
2016-06-06 10:39                     ` George Dunlap
2016-06-06 10:52                       ` Ian Jackson
2016-06-06 11:43                         ` George Dunlap
2016-06-06 12:49                     ` George Dunlap
2016-06-07 14:08                     ` George Dunlap
2016-06-07 14:27                       ` Olaf Hering
2016-06-08 10:17                       ` Ian Jackson
2016-06-07 19:06                     ` Olaf Hering
2016-06-08 10:18                       ` Ian Jackson
2016-06-08 10:23                         ` George Dunlap [this message]
2016-06-08 10:30                           ` Ian Jackson
2016-06-08 10:49                             ` George Dunlap
2016-06-08 11:13                               ` Olaf Hering
2016-06-08 15:56                                 ` Konrad Rzeszutek Wilk
2016-06-03 11:50                   ` Olaf Hering
2016-05-31 12:10       ` Jan Beulich
2016-05-31 13:41         ` George Dunlap
2016-05-31 14:10           ` Jan Beulich
2016-05-31 16:15     ` Konrad Rzeszutek Wilk
2016-06-08 11:38 ` Wei Liu
2016-06-08 12:04   ` Olaf Hering
2016-06-08 12:09     ` Wei Liu

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