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From: "Roger Pau Monné" <roger.pau@citrix.com>
To: xen-devel@lists.xenproject.org
Cc: Wei Liu <wei.liu2@citrix.com>,
	Ian Jackson <ian.jackson@eu.citrix.com>,
	Ian Campbell <ian.campbell@citrix.com>
Subject: Re: [PATCH v4 5/6] libxl: add options to enable/disable emulated devices
Date: Fri, 22 Jan 2016 18:04:37 +0100	[thread overview]
Message-ID: <56A26125.8090804@citrix.com> (raw)
In-Reply-To: <1453395092-88090-6-git-send-email-roger.pau@citrix.com>

El 21/01/16 a les 17.51, Roger Pau Monne ha escrit:
> Allow enabling or disabling emulated devices from the libxl domain
> configuration file. For HVM guests with a device model all the emulated
> devices are enabled. For HVM guests without a device model no devices are
> enabled by default, although they can be enabled using the options provided.
> The arbiter of whether a combination is posible or not is always Xen, libxl
> doesn't do any kind of check.
> 
> This set of options is also propagated inside of the libxl migration record
> as part of the contents of the libxl_domain_build_info struct, so that when
> the other end (restore) creates the domain the same set of devices are
> enabled. This is important for future compatibility, in case we decide to
> enable some emulated devices by default for HVMlite guests, old HVMlite
> guests migrated to newer versions should continue to see the same set of
> emulated devices.
> 
> It has been discussed that it would be better to avoid having this
> information inside of the libxl stream, and to instead rely on which devices
> get their context loaded inside of Xen on resume. This of course requires
> more work and it also has certain issues, like the fact that some devices
> don't restore a context at all (like VGA). The consensus is that the
> solution presented in this patch is not going to prevent further
> developments in this direction, and can always be used as a check to make
> sure the Xen context and the libxl context are in sync.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
> ---
> Cc: Ian Jackson <ian.jackson@eu.citrix.com>
> Cc: Ian Campbell <ian.campbell@citrix.com>
> Cc: Wei Liu <wei.liu2@citrix.com>

To tools committers: please refrain from pushing this until we have a
clear view on which devices we might want to enable in the future.
Adding a bunch of libxl options that are never going to be allowed
doesn't make any sense.

Roger.


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  reply	other threads:[~2016-01-22 17:05 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-21 16:51 [PATCH v4 0/6] HVMlite: DomU fixes and a Dom0 preparatory patch Roger Pau Monne
2016-01-21 16:51 ` [PATCH v4 1/6] libelf: rewrite symtab/strtab loading for Dom0 Roger Pau Monne
2016-01-21 17:29   ` Ian Jackson
2016-01-21 17:55     ` Roger Pau Monné
2016-01-21 18:44       ` Ian Jackson
2016-01-22  8:11       ` Jan Beulich
2016-01-22  9:58         ` Roger Pau Monné
2016-01-21 16:51 ` [PATCH v4 2/6] libxl: introduce LIBXL_VGA_INTERFACE_TYPE_UNKNOWN Roger Pau Monne
2016-01-22 10:59   ` Ian Campbell
2016-01-21 16:51 ` [PATCH v4 3/6] libxl: initialise the build info before calling prepare_config Roger Pau Monne
2016-01-22 11:00   ` Ian Campbell
2016-01-21 16:51 ` [PATCH v4 4/6] x86/PV: allow PV guests to have an emulated PIT Roger Pau Monne
2016-01-22 10:48   ` Jan Beulich
2016-01-22 11:03     ` Ian Campbell
2016-01-21 16:51 ` [PATCH v4 5/6] libxl: add options to enable/disable emulated devices Roger Pau Monne
2016-01-22 17:04   ` Roger Pau Monné [this message]
2016-01-25  9:33     ` Ian Campbell
2016-01-21 16:51 ` [PATCH v4 6/6] x86/HVM: report the set of enabled emulated devices through CPUID Roger Pau Monne
2016-01-22 10:57   ` Jan Beulich
2016-01-22 12:43     ` Roger Pau Monné
2016-01-22 13:24       ` Jan Beulich
2016-01-22 14:41         ` Roger Pau Monné
2016-01-22 15:02           ` Jan Beulich
2016-01-22 15:41             ` Roger Pau Monné
2016-01-22 13:34       ` Andrew Cooper
2016-01-22 14:59         ` Roger Pau Monné
2016-01-22 15:31           ` Jan Beulich
2016-01-22 15:51             ` Roger Pau Monné
2016-01-25 11:23               ` Jan Beulich

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