Re: [Qemu-devel] [PATCH 0/3] net: reimplement -net nic diagnostic fix

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

On 20 May 2011 16:55, Jan Kiszka <jan.kiszka@siemens.com> wrote:
> On 2011-05-20 17:49, Peter Maydell wrote:
>> This patchset reverts commit f68b9d672, which was triggering
>> spuriously for NICs created via -device rather than -net nic.
>> It then reimplements the improved diagnostics with a different
>> approach which only applies to '-net nic'. (It's only -net nic
>> devices that can be ignored (ie not instantiated); -device
>> nic devices are always instantiated. Checking for -device user
>> errors like "this device wasn't plugged into any bus" is
>> a separate issue not addressed here.)
>
> But we still have the problem that qemu_new_nic does not call
> net_init_nic. That means e.g. that NICs instantiated via -device don't
> participate in automatic MAC assignment. Maybe fixing that makes this
> series obsolete.

I think that avoiding MAC address clashes should be done by
having net_init_nic() call qemu_macaddr_default_if_unset()
rather than doing its own MAC assignment.

Having qemu_new_nic() call net_init_nic() is a bit tricky
because (a) as you said earlier you need to avoid doing
it for NICs which were created from nd_table entries in the
first place and (b) it imposes a new limit on the number
of NICs you can create via -device which wasn't there before
(because nd_table is fixed size).

I think I agree with Paul Brook's comment on IRC that the
real long term solution is for nd_table[] to go away completely,
(ie not for the new qdev option code to add entries in nd_table[]
by calling net_init_nic().)

-- PMM