Re: [Xen-devel] Automotive PV drivers project request

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Tue, 10 Jun 2014, Artem Mygaiev wrote:
> David, Lars,
> 
> Indeed, userspace drivers in Android essentially are set of so libraries for 
> libhardware which provides some sort of a HAL
> to kenel drivers. In order to simplify things we can avoid kernel drivers in 
> Andorid and go straight to userspace.
> 
> I do not think that it is correct to mix PV drivers backends with QEMU, we do 
> not do full emulation in most cases, just
> PVHVM

You don't need to do any emulation whatsoever in order to run the PV
backends in QEMU.  You can simply execute QEMU to provide only the PV
backends and nothing else by passing -M xenpv.

In fact we use QEMU as userspace PV backend provider for x86 PV guests,
that do not require any emulation on the hypervisor side at all.

Having the PV backends in QEMU gives you a common framework to write PV
drivers and access xenstore (see hw/xen/xen_backend.c).


> Artem Mygaiev |ÂAVP - Delivery
> GlobalLogic
> P +380.44.4929695 ext.2023ÂM +380.67.9211131 S rosenkrantzguildenstern 
> www.globallogic.com
> 
> http://www.globallogic.com/email_disclaimer.txt
> 
> 
> On Tue, Jun 10, 2014 at 5:09 PM, Lars Kurth <lars.kurth@xxxxxxx> wrote:
>       On 10/06/2014 13:38, David Vrabel wrote:
>             On 05/06/14 14:22, Artem Mygaiev wrote:
>                   David, agree on all kernel drivers but what about userspace 
> backends
>                   and other OSes?
> 
>             I don't have an opinion on user space drivers. ÂI would suggest 
> that
>             userspace backends live with the existing ones in qemu.
> 
>             Are userspace frontends useful? ÂIsn't a kernel driver required 
> for
>             proper access control?
> 
> David,
> 
> I believe the answer is 
> inhttp://wiki.xenproject.org/wiki/XPDS13_BoF_Notes_:_Seeding_an_Android_and_Embedded_ecosystem#Missing_Pieces_for_a_complet
> e_Android_system_on_top_of_Xen
> 
> As far as I understand, Android requires functionality to be made available 
> via userspace drivers. These would sit
> on top of the kernel drivers.
> 
> Lars
> 
> 
> 
>

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