[Qemu-devel] Regression "Warning: more nics requested than this machine supports"

[Qemu-devel] Regression "Warning: more nics requested than this machine supports"

[Markus Armbruster]

Watch this:

    $ qemu-system-x86_64 -nodefaults -enable-kvm -m 384 -vnc :0 -S -netdev user,id=net0 -device e1000,netdev=net0
    Warning: more nics requested than this machine supports; some have been ignored
    (qemu) info network
    Devices not on any VLAN:
      net0: net=10.0.2.0, restricted=n peer=e1000.0
      e1000.0: model=e1000,macaddr=52:54:00:12:34:56 peer=net0

Culprit is

commit f68b9d672b90dedc79aeb9b44607f484dbe46a6b
Author: Peter Maydell <peter.maydell@linaro.org>
Date:   Tue Mar 22 18:39:40 2011 +0000

    net: Improve the warnings for dubious command line option combinations
    
    Improve the warnings we give if the user specified a combination of -net
    options which don't make much sense:
     * Don't warn about anything if the config is the implicit default
       "-net user -net nic" rather than one specified by the user (this will
       only kick in for boards with no NIC or if CONFIG_SLIRP is not set)
     * Diagnose the case where the user asked for NICs which the board
       didn't instantiate (for example where the user asked for two NICs
       but the board only supports one)
    
    Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
    Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

Its count of requested NICs is blissfully unaware of -device.  In my
example, it comes up with nb_nics == 0 and seen_nics == 1.

Re: [Qemu-devel] Regression "Warning: more nics requested than this machine supports"

[Peter Maydell]

On 16 May 2011 17:58, Markus Armbruster <armbru@redhat.com> wrote:
>    $ qemu-system-x86_64 -nodefaults -enable-kvm -m 384 -vnc :0 -S -netdev user,id=net0 -device e1000,netdev=net0
>    Warning: more nics requested than this machine supports; some have been ignored
>    (qemu) info network
>    Devices not on any VLAN:
>      net0: net=10.0.2.0, restricted=n peer=e1000.0
>      e1000.0: model=e1000,macaddr=52:54:00:12:34:56 peer=net0
>
> Culprit is
>    net: Improve the warnings for dubious command line option combinations

> Its count of requested NICs is blissfully unaware of -device.  In my
> example, it comes up with nb_nics == 0 and seen_nics == 1.

As far as I can determine, "-device e1000,netdev=0" doesn't go through
net_init_nic() and doesn't put an entry in the nd_table[] for the NIC.
This means it's broken, because a lot of board models look in nd_table[]
to determine whether the user requested a NIC and whether it's the right
type. So I think that in some ways this is just showing up an existing
problem with trying to instantiate a network card with -device.

-- PMM

Re: [Qemu-devel] Regression "Warning: more nics requested than this machine supports"

[Jan Kiszka]

On 2011-05-20 13:19, Peter Maydell wrote:
> On 16 May 2011 17:58, Markus Armbruster <armbru@redhat.com> wrote:
>>    $ qemu-system-x86_64 -nodefaults -enable-kvm -m 384 -vnc :0 -S -netdev user,id=net0 -device e1000,netdev=net0
>>    Warning: more nics requested than this machine supports; some have been ignored
>>    (qemu) info network
>>    Devices not on any VLAN:
>>      net0: net=10.0.2.0, restricted=n peer=e1000.0
>>      e1000.0: model=e1000,macaddr=52:54:00:12:34:56 peer=net0
>>
>> Culprit is
>>    net: Improve the warnings for dubious command line option combinations
> 
>> Its count of requested NICs is blissfully unaware of -device.  In my
>> example, it comes up with nb_nics == 0 and seen_nics == 1.
> 
> As far as I can determine, "-device e1000,netdev=0" doesn't go through
> net_init_nic() and doesn't put an entry in the nd_table[] for the NIC.
> This means it's broken, because a lot of board models look in nd_table[]
> to determine whether the user requested a NIC and whether it's the right
> type. So I think that in some ways this is just showing up an existing
> problem with trying to instantiate a network card with -device.

qemu_new_nic must call net_init_nic so that this works properly. Of
course we need to avoid calling it multiple times when the adapter is
still instantiated via the old -net or via board init code.

Jan

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux