Re: [Qemu-arm] [Qemu-devel] [PATCH v2 2/2] hw/arm: Add Arm Enterprise machine type

[Daniel P . Berrangé]

On Wed, Jul 25, 2018 at 01:19:09PM +0100, Peter Maydell wrote:
> On 25 July 2018 at 12:44, Andrew Jones <address@hidden> wrote:
> > On Wed, Jul 25, 2018 at 06:46:59PM +0800, Hongbo Zhang wrote:
> >> For Armv7, there is one typical platform 'vexpress', but for Armv8, no
> >
> > Wasn't the vexpress model designed for a specific machine?
> 
> Yes.
> 
> > Namely for
> > Arm's simulator?
> 
> No.
> 
> > Is the vexpress model really something typical among
> > all the Armv7 platforms?
> 
> No.
> 
> "Vexpress" is a model specifically of a development board
> produced by Arm (the versatile express). It's useful if you
> want to run code that runs on that devboard, but (as with
> most of the devboards we model), it's not necessarily ideal,
> because it has all the limitations of the real hardware it's
> modelling (in this case the big ones are limited memory, no PCI).
> The hardware it models is also quite old now (maybe 7 or 8 years)
> and it's not really "typical" of anything. (In the primarily
> embedded space where most v7 CPUs are there's not really anything
> that could be described as "typical" anyway: everything is
> different.)
> 
> For most people who just want to run Linux on an emulated v7 CPU,
> I would recommend the "virt" board, for the same reasons I
> recommend it for v8 cores.
> 
> >> such typical one, the 'virt' is typically for running workloads, one
> >> example is using it under OpenStack.
> >> So a 'typical' one for Armv8 is needed for firmware and OS
> >> development, similar like 'vexpress' for Armv7.
> >
> > What is a "typical" Armv8 machine? What will a typical Armv8 machine be in
> > two years?
> >
> > Note, I'm not actually opposed to the current definition (because I don't
> > really have one myself). I'm just opposed to hard coding one.
> 
> AIUI the aim here is to provide an emulated platform that is
> set up in the way that server-style armv8 machines are
> recommended to be set up, so it can be used as a testbed and
> demonstration for the firmware/OS software stack. The hope
> is that following "best practices" results in a "typical"
> machine :-)  But the word "typical" is probably not really
> very helpful here...
> 
> I would expect that in the future we'd want this machine type
> to evolve with the recommendations for how to build server
> platform hardware, which might indeed be different in two years,
> since it would be the development platform for writing/testing
> the firmware/OS stack for that two-years-time hardware.

Would iut make any sense to call the machine  "refplatform"  or "refboard"
to indicate it is a generic reference platform, not specifically following
any particular real impl, albeit influence by the sbsa spec.

Regards,
Daniel
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