Re: [PATCH OSSTEST v5] Add arm64 build and test jobs

[Ian Campbell <ian.campbell@citrix.com>]

On Tue, 2015-09-29 at 17:33 +0100, Ian Jackson wrote:
> Ian Campbell writes ("Re: [PATCH OSSTEST v5] Add arm64 build and test
> jobs"):
> > Not quite, since the arm32 and arm64 h/w is distinct. These tests won't
> > run
> > on any of the arm32 hardware we have and the existing armhf tests won't
> > run
> > on the new hwardware (for reasons I'll hopefully explain in the course
> > of
> > answering the next question below).
> 
> Ah.  And we are hoping to get some arm64 hardware "RSN" ?

Yes indeed.

> > > Also, why are there no
> > >   test-arm64-armhf
> > > jobs ?
> > 
> > "It's complicated".
> ...
> > But each new ARMv8 processor implementation involves a certain amount
> > of
> > per vendor code in Linux in arch/arm64 (the AArch64 AKA 64-bit port).
> > That
> > support is rarely (never?) also added to arch/arm (the 32-bit port).
> > Hence
> > it would be unusual to even find a 32-bit kernel to run on a 64-bit
> > capable
> > processor.
> ...
> > I suppose there is also a fourth possibility which is a fully 64-bit
> > host
> > with 32-bit guests, which is probably the most plausible and useful
> > one,
> > and something we ought to consider testing at some point.
> 
> It was this latter case which I was considering.  Is this per vendor
> code in Linux needed for a non-dom0 Xen guest to work ?

No, they should work with just the Xen guest support.

> But anyway, I guess this means we can punt on this for now.

Yes please.

>   Thanks
> for the explanation.
> 
> Ian.