Re: [Qemu-devel] [PATCH v9 07/11] hw/arm: Add 'virt' platform

[Christoffer Dall]

On Fri, Nov 22, 2013 at 06:17:51PM +0000, Peter Maydell wrote:
> On 22 November 2013 18:11, Christoffer Dall <address@hidden> wrote:
> > On Fri, Nov 22, 2013 at 05:17:14PM +0000, Peter Maydell wrote:
> >> + * Emulate a virtual board which works by passing Linux all the 
> >> information
> >> + * it needs about what devices are present via the device tree.
> >> + * There are some restrictions about what we can do here:
> >> + *  + we can only present devices whose Linux drivers will work based
> >> + *    purely on the device tree with no platform data at all
> >> + *  + we want to present a very stripped-down minimalist platform,
> >> + *    both because this reduces the security attack surface from the guest
> >> + *    and also because it reduces our exposure to being broken when
> >> + *    the kernel updates its device tree bindings and requires further
> >> + *    information in a device binding that we aren't providing.
> >> + * This is essentially the same approach kvmtool uses.
> >
> > nit: questionable value of this last line in the comment.
> 
> Well, it says we're not doing something completely bonkers
> of our own devising ;-)
> 

;)

> > +    vbi->bootinfo.board_id = -1;
> >
> > board_id = -1 ?
> 
> This is what the kernel's boot protocol says you should
> pass as the board ID register for boards which are new
> enough that they only support booting via device tree
> and not the old-style board ID number system.
> 
ok, thanks.
-Christoffer