Re: [Xen-devel] [PATCH RFC 04/12] libxl: create a local xenstore libxl and device-model dir for guests

[Roger Pau Monnà <roger.pau@xxxxxxxxxx>]

On 25/09/13 15:48, Ian Campbell wrote:
> On Mon, 2013-09-23 at 12:30 +0200, Roger Pau Monne wrote:
>> If libxl is executed inside a guest domain it needs write access to
>> the local libxl xenstore dir (/local/<domid>/libxl) to store internal
>> data.
> 
> These sorts of changes need a patch against docs/misc/xenstore-paths.txt
> too.

Ack.

> 
>>  This also applies to Qemu which needs a
>> /local/<domid>/device-model xenstore directory.
> 
> Is this a new requirement or a separate preexisting issue? How have we
> lived without it?

This entry is so far only created on Dom0 (because it's the only domain
that launches Qemu, and is created by Qemu if needed), but when running
on a guest, the guest doesn't have permissions to write on
/local/<domid>/, so we have to create the directory in the toolstack
domain and assign write permissions for the guest.

This path is hardcoded in Qemu, so it's quite difficult to change it,
that's why I've opted for creating it on domain creation.

> 
>> This patch creates the mentioned directories for each guest launched
>> from libxl.
> 
> I don't really like leaking toolstack "internals" into the normal guest
> namespace. Can we add an option to specify "this is a toolstack domain"
> and key off that?

OK, something like driver_domain=1|0

> I also wonder if this shouldn't be /libxl/<domid> at the top level.

I don't have a strong opinion on this, but I generally prefer to keep
all the xenstore related keys for a domain inside /libxl/<domid>.


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel