Re: [Xen-devel] [PATCH RFC] xen: arm: Log a warning message when a deprecated hypercall is used

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2015-02-04 at 09:41 +0000, Ard Biesheuvel wrote:
> On 20 January 2015 at 10:52, Ian Campbell <ian.campbell@xxxxxxxxxx> wrote:
> > A few folks have been caught out by OSes which call e.g.
> > HYPERVISOR_event_channel_op_compat which has been deprecated since
> > 3.2.2 (i.e. long before Xen on ARM). Existing x86 code can still
> > safely and quietly using those calls, waiting for an unsuspecting ARM
> > porter to turn up and trip over it. This turns out to be rather
> > perplexing when it happens, since it can be obscured e.g. by various
> > conditionals like __XEN_INTERFACE_VERSION__ what is actually being
> > called.
> >
> > Note that I'm making a distinction here between hypercalls which are
> > simply not used/implemented on arm (yet) and those which were
> > deprecated and replaced by a newer variant prior to Xen on ARM even
> > being invented.  The latter will never be implemented on ARM and have
> > non-deprecated aliases leading to confusion so those are the ones for
> > which a warning is useful.
> >
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > Cc: Jan Beulich <JBeulich@xxxxxxxx>
> > Cc: Keir Fraser <keir@xxxxxxx>
> > Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
> > Cc: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> > ---
> > RFC since I'm not sure how extreme our reaction ought to be here, e.g.
> > I considered domain_crash() or even panic() when in a debug build. A
> > XENLOG_DEBUG message is about the most benign of the options.
> >
> > Jan/Keir, although this is ARM specific I'd welcome your views as
> > x86/REST maintainers.
> >
> > Ard, I've not actually run this -- any chance you could re-b0rk your
> > Tianocore image and give it a go?
> 
> I get a bunch of lines in my log looking like
> 
> (XEN) traps.c:1162:d4v0 d4v0: deprecated hypercall 16
> 
> so
> 
> Tested-by: Ard Biesheuvel <ard@xxxxxxxxxx>

Thanks!



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