Re: [Xen-devel] [PATCH v3 4/9] livepatch: Sync cache of build-id before using it first time.

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Mon, Aug 15, 2016 at 11:46:13AM +0100, Andrew Cooper wrote:
> On 15/08/16 11:38, Jan Beulich wrote:
> >>>> On 14.08.16 at 23:52, <konrad.wilk@xxxxxxxxxx> wrote:
> >> We don't print at bootup time the build-id. The reason is
> >> that xen_build_init and livepatch_init are both __initcall
> >> type routines. This meant that when livepatch_init called
> >> xen_build_id, it would return -ENODATA as build_id_len was
> >> not setup yet (b/c xen_build_init would be called later).
> >>
> >> We fix this by calling xen_build_init in livepatch_init which
> >> allows us to print the build-id of the hypervisor.
> >>
> >> We also keep xen_build_init as __initcall because build-id
> >> can be built without livepatching being enabled (so
> >> no livepatch_init being called).
> > Now if the build ID is potentially useful outside of live patching,
> > shouldn't its logging also be done outside of livepatch code?

And by logging you mean the printk of it which is right now
only done in common/livepatch.c ?
> 
> IMO the Build ID should be available and printed irrespective of live
> patching.
> 
> It is useful information simply to identify the hypervisor.

Right, and it is.

As in you can build the hypervisor without livepatching and the build-id will 
be built in.

I can certainly make xen_build_id call:

 printk(XENLOG_INFO "build-id: %*phN\n", build_id_len, build_id_p);

which would be a much simpler fix :-)

Let me do that.

> 
> ~Andrew

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