RE: [RFC PATCH V1 07/12] A collection of tweaks to be able to run emulator in driver domain

[Paul Durrant <xadimgnik@xxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich <jbeulich@xxxxxxxx>
> Sent: 05 August 2020 17:20
> To: Oleksandr Tyshchenko <olekstysh@xxxxxxxxx>; Paul Durrant <paul@xxxxxxx>
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; Oleksandr Tyshchenko 
> <oleksandr_tyshchenko@xxxxxxxx>; Andrew
> Cooper <andrew.cooper3@xxxxxxxxxx>; George Dunlap <george.dunlap@xxxxxxxxxx>; 
> Ian Jackson
> <ian.jackson@xxxxxxxxxxxxx>; Julien Grall <julien@xxxxxxx>; Stefano Stabellini
> <sstabellini@xxxxxxxxxx>; Wei Liu <wl@xxxxxxx>; Daniel De Graaf 
> <dgdegra@xxxxxxxxxxxxx>
> Subject: Re: [RFC PATCH V1 07/12] A collection of tweaks to be able to run 
> emulator in driver domain
> 
> On 03.08.2020 20:21, Oleksandr Tyshchenko wrote:
> > From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
> >
> > Trying to run emulator in driver domain I ran into various issues
> > mostly policy-related. So this patch tries to resolve all them
> > plobably in a hackish way. I would like to get feedback how
> > to implement them properly as having an emulator in driver domain
> > is a completely valid use-case.
> 
> From going over the comments I can only derive you want to run
> an emulator in a driver domain, which doesn't really make sense
> to me. A driver domain has a different purpose after all. If
> instead you mean it to be run in just some other domain (which
> also isn't the domain controlling the target), then there may
> be more infrastructure changes needed.
> 
> Paul - was/is your standalone ioreq server (demu?) able to run
> in other than the domain controlling a guest?
> 

Not something I've done yet, but it was always part of the idea so that we 
could e.g. pass through a device to a dedicated domain and then run multiple 
demu instances there to virtualize it for many domUs. (I'm thinking here of a 
device that is not SR-IOV and hence would need some bespoke emulation code to 
share it out). That dedicated domain would be termed the 'driver domain' simply 
because it is running the device driver for the h/w that underpins the 
emulation.

  Paul