Re: [Xen-devel] [PATCH v1] Add build-id to XENVER hypercall.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 09.10.15 at 15:25, <konrad.wilk@xxxxxxxxxx> wrote:
> On Fri, Oct 09, 2015 at 01:15:42PM +0100, Andrew Cooper wrote:
>> On 09/10/15 09:17, Jan Beulich wrote:
>> >>>> On 09.10.15 at 04:56, <konrad.wilk@xxxxxxxxxx> wrote:
>> >> However they also change the behavior of the existing hypercall
>> >> for XENVER_[compile_info|changeset|commandline] and make them
>> >> dom0 accessible. This is if XSM is built in or not (though with
>> >> XSM one can expose it to a guest if desired).
>> > Wasn't the outcome of the previous discussion that we should not
>> > alter default behavior for existing sub-ops?
>> 
>> I raised a worry that some guests might break if they suddenly have
>> access to this information cut off.
> 
> Let me double-confirm that the guests are OK with this being
> gone. I did ran tests to see if the worked, but hadn't actually tried
> acessing (/sys/hypervisor/xen*) the values.

Well, this is the kind of thing you can't find out by testing _some_
guest(s) - you'd need to test with all possible ones, which of course
is not feasible. Hence we need to be very conservative when
deciding to restrict part of a so far guest-kind-indifferent ABI.

Jan


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