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

[Peter Maydell <peter.maydell@linaro.org>]

On 22 November 2013 18:11, Christoffer Dall <christoffer.dall@linaro.org> 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.

-- PMM