RE: [Xen-devel] xenstore -- read UUID

[dinesh chandrasekaran <dinesh_chan8@xxxxxxxxxxx>]

Hi Derek,

they were 2 seperate questions... sorry for the typos...
How to access xenstore from Dom-0? -- which you said 'YES'...
And How to access xenstore from hypervosor?
Yes.. as you said 'make xen' doesnt include /usr/include libraries and I did check that...

If the hypervisor has no knowledge about XenStore, Dom-0 must have the full control over the xenstore.
I need to build a table with some fields one of which should never change during a VMs lifetime.
For example, if I chose the domain_id whose value is transient, If the VM reboots, its domain_id changes.
That is the reason why I opted for the UUID of a domain that persists over time even after migration to another machine.
The only way I could get a domain's UUID is through the xenstore and want to take away domain-0 from the picture, which
according to you is almost impossible.

anyway out?

regards,
Dinesh C

> Date: Tue, 9 Sep 2008 21:37:57 +0100
> From: Derek.Murray@xxxxxxxxxxxx
> To: dinesh_chan8@xxxxxxxxxxx
> Subject: Re: [Xen-devel] xenstore -- read UUID
> CC: xen-devel@xxxxxxxxxxxxxxxxxxx; xen-users@xxxxxxxxxxxxxxxxxxx
>
> Hi Dinesh,
>
> In what context are you trying to run this code? You say that you want
> to read the UUID from Dom0, but xen/common/memory.c is part of the
> hypervisor (and not Dom0). If you try to compile that code into
> xen/common/memory.c, it will fail, because building the hypervisor
> does not include the user-space headers (i.e. the contents of
> /usr/include/).
>
> The hypervisor has (almost) no knowledge about XenStore, and so it
> would be very difficult to access XenStore from there. However, if you
> want to access this information in Dom0, your code should work in a
> user-space application.
>
> Could you provide more details about what you are trying to do?
>
> Regards,
>
> Derek Murray.
>
> On Tue, Sep 9, 2008 at 8:36 PM, dinesh chandrasekaran
> <dinesh_chan8@xxxxxxxxxxx> wrote:
> > Hi All,
> >
> > Im trying to read the UUID of a domain-U from domain-0 using the
> > following code from inside say xen/common/memory.c.
> >
> > The include file <xs.h> is present both in /usr/include and
> > tools/xenstore/xs.h
> >
> > #include <xs.h>
> > static int get_domain_uuid(unsigned int domain_id) {
> > struct xs_handle *xs;
> > xs_transaction_t t;
> > char *path;
> > unsigned int *len;
> > void *uuid;
> > xs = xs_daemon_open();
> > if (xs == NULL)
> > return 1;
> > path = xs_get_domain_path(xs, domain_id);
> > if (path == NULL)
> > return 1;
> > strcat (path, '/uuid');
> > len = strlen(path) + 1;
> > uuid = xs_read(xs, t, path, len);
> > printf('%lx \n', (char) (*uuid));
> > xs_daemon_close(xs);
> > free(path);
> > return 0;
> > }
> >
> > when compiled throws an error ( xs.h - no such file or directory).
> >
> > How to access xenstore and read the doamin UUID from dom-0 specifically from
> > inside xen/common/memory.c?
> >
> > regards,
> > Dinesh C
> >
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