[Pkg-xen-devel] [PATCH 02/12] debian/rules: Only install PV shim for supported architectures

[Elliott Mitchell]

On Thu, Sep 17, 2020 at 04:51:04PM +0100, Ian Jackson wrote:
> Elliott Mitchell writes ("[PATCH 02/12] debian/rules: Only install PV shim for supported architectures"):
> > UEFI is available on ARM64 devices, but presently there is no Xen
> > configuration for building the PV shim on ARM.  The install step needs
> > to match the build step, so modify the install step.
> 
> >  	@# shimless arches, so it does not need to be conditional.
> > -	$(MAKE) $(make_args_xen) DESTDIR=$t $(make_args_xen) \
> > -		-C tools/firmware install-shim
> > +	case $(flavour) in \
> > +	amd64|i386) \
> > +		$(MAKE) $(make_args_xen) DESTDIR=$t $(make_args_xen) \
> > +			-C tools/firmware install-shim \
> > +	;; \
> > +	esac
> 
> I don't understand.  The effect of your patch is to avoid running
> make install-shim on armhf and arm64.
> 
> But on those platforms there is as you say no shim[1], so make
> install-shim ought to do nothing.  We build armhf and arm64 on the
> Debian buildds from the sources before your patch.
> 
> I'm not sure what the connection is between the PV shim and UEFI ?
> These are separate concepts.
> 
> The PV shim is there to run PV guests in an HVM container, mostly for
> Spectre reasons.  There is no shim for ARM because ARM does not have
> HVM guests nor PV ones; it has only one type of guest which is roughly
> like an x86 PVH guest.

Okay, the commit message could be totally buggered due to my knowledge
being very thin here.

What I observed during build attempts was the build failed.  Most likely
on ARM the install target doesn't invoke the install-shim target, while
the install-shim target assumes the files exist.  Note the package was
rather close to 4.11 when I tried this.


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