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

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

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@suse.com> 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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