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

[David Vrabel <david.vrabel@xxxxxxxxxx>]

On 23/03/16 10:55, 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.
> 
> That is it however.  It specifically shouldn't be used for any other
> decisions, as it isn't relevant.

I think it should be the toolstack that presents this information.

I don't think we should add a new kernel ABI for this.

David


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