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From: Wei Liu <wei.liu2@citrix.com>
To: Juergen Gross <jgross@suse.com>
Cc: wei.liu2@citrix.com, stefano.stabellini@eu.citrix.com,
	George.Dunlap@eu.citrix.com, ian.jackson@eu.citrix.com,
	cyliu@suse.com, xen-devel@lists.xen.org
Subject: Re: [PATCH v3 5/5] libxl: add domain config parameter to force start of qemu
Date: Thu, 24 Mar 2016 20:35:20 +0000	[thread overview]
Message-ID: <20160324203520.GF14940@citrix.com> (raw)
In-Reply-To: <20160324202845.GE14940@citrix.com>

On Thu, Mar 24, 2016 at 08:28:45PM +0000, Wei Liu wrote:
> On Wed, Mar 23, 2016 at 01:24:07PM +0100, Juergen Gross wrote:
> > Today the device model (qemu) is started for a pv domain only in case
> > a device requiring qemu is specified in the domain configuration
> > (qdisk, vfb, channel). If there is no such device the device model
> > isn't started and hence it is impossible to add such a device to the
> > domain later.
> > 
> > Add a domain configuration parameter to specify the device model is
> > to be started in any case. This will enable adding devices with a
> > qemu based backend later.
> > 
> > While the optimal solution would be to start the device model
> > automatically when needed this would require some major rework of
> > libxl at multiple places.
> > 
> > Signed-off-by: Juergen Gross <jgross@suse.com>
> I can't say I like this.
> Libxl can be made smart enough to detect whether starting a device model
> is required (as you already did in previous patch) then start qemu on
> demand.
> There is a xen-attach mode in qemu, and libxl already has machinery for
> starting qemu. I suspect what you need to do is refactoring existing
> code and expose the right parameter for qemu. Then you wouldn't need
> this user visible option at all. You would also save the resources for
> always having an idle qemu in toolstack domain.
> Let me know if this is to vague.

Actually I don't think this is your problem. I would consider this a bug
in libxl for not starting qemu on demand. I can take a stab at it, but
that will need to wait until next release.

I think the functionality you care about  can live without this patch,
but I'm not sure if it would become too cumbersome to use.


> Wei.

Xen-devel mailing list

  reply	other threads:[~2016-03-24 20:35 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-23 12:24 [PATCH v3 0/5] libxl: add support for qemu base pvusb backend Juergen Gross
2016-03-23 12:24 ` [PATCH v3 1/5] libxl: make libxl__need_xenpv_qemu() operate on domain config Juergen Gross
2016-03-24 20:28   ` Wei Liu
2016-03-25  6:13     ` Juergen Gross
2016-03-23 12:24 ` [PATCH v3 2/5] libxl: add new pvusb backend "qusb" provided by qemu Juergen Gross
2016-03-25  2:23   ` Chun Yan Liu
     [not found]   ` <56F5119C02000066000C0F24@suse.com>
2016-03-25  6:29     ` Juergen Gross
2016-03-25  6:38       ` Chun Yan Liu
2016-03-23 12:24 ` [PATCH v3 3/5] libxl: add service function to check whether device model is running Juergen Gross
2016-03-24 20:28   ` Wei Liu
2016-03-23 12:24 ` [PATCH v3 4/5] libxl: check for dynamic device model start required Juergen Gross
2016-03-25  2:06   ` Chun Yan Liu
     [not found]   ` <56F50DC102000066000C0EF4@suse.com>
2016-03-25  6:25     ` Juergen Gross
2016-03-25  6:29       ` Chun Yan Liu
2016-03-23 12:24 ` [PATCH v3 5/5] libxl: add domain config parameter to force start of qemu Juergen Gross
2016-03-24 20:28   ` Wei Liu
2016-03-24 20:35     ` Wei Liu [this message]
2016-03-25  6:20       ` Juergen Gross
2016-03-25  6:16     ` Juergen Gross

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