Re: [Xen-devel] [PATCH] tools: fix xen-detect to correctly identify domU type

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 03/23/2016 07:33 AM, Juergen Gross wrote:
> On 23/03/16 11:55, Andrew Cooper wrote:
> > On 23/03/16 10:52, Juergen Gross wrote:
> > > On 23/03/16 11:32, David Vrabel wrote:
> > > > On 23/03/16 10:25, Jan Beulich wrote:
> > > > > > > > On 23.03.16 at 11:14, <JGross@xxxxxxxx> wrote:
> > > > > > 7. Report type according to features found (this is a little bit
> > > > > >     ugly: we have to rely on the current hypervisor implementation
> > > > > >     regarding the bits set for the different guest types).
> > > > > Well, in some of the cases feature flags only make sense for one
> > > > > kind of guest, so if such a flag is set it could be used as positive
> > > > > indication (while it being clear may then still mean nothing).
> > > > >
> > > > > > Would it make sense to add another file to /sys/hypervisor/properties?
> > > > > > Something like guest_type, containing "pv", "hvm" or "pvh"? If existing
> > > > > > this could be used to report the guest type.
> > > > > That would seem a good idea to me. What do others, namely
> > > > > Linux maintainers, think?
> > > > What's the use case for user space knowing if it's in a PV or HVM domain?
> > > The first thing coming to my mind would be diagnostic tools.
> > Having the admin able to tell for informational purposes is useful.
> > They can find out by looking at the top of `dmesg`, but a hypervisor
> > sysfs node is cleaner than requiring the admin to know every printk()
> > variant that Xen puts out.
> Especially on a long running guest this information might be not
> available in case of trouble.
What about dmidecode?

Unprivileged PV guests will return nothing:

[root@dhcp-burlington7-2nd-B-east-10-152-55-140 ~]# dmidecode
# dmidecode 2.11
# No SMBIOS nor DMI entry point found, sorry.
[root@dhcp-burlington7-2nd-B-east-10-152-55-140 ~]#


HVM guests will say something like:

System Information
    Manufacturer: Xen
    Product Name: HVM domU

and dom0 will report actual info.

-boris

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