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

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

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" ?

> > 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 ?

But anyway, I guess this means we can punt on this for now.  Thanks
for the explanation.

Ian.

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