[Qemu-discuss] How to select specific qemu net 'nic' device

[mbilal]

Hi,

I'm using qemu emulation for xilinx zcu102 platform, this board have 
four networking GEM0, GEM1, GEM2 and GEM3 devices.

To run network demo on this board *only* require GEM3 device to be 
configure while other GEM devices don't need to be configure, that's why 
u-boot and other RTOS only configure GEM3 device.


QEMU is enabling these GEM devices  with networking '-net nic' option 
and QEMU consider first '-net nic' option for GEM0 and second '-net nic' 
option for GEM1 and so on. that's why if need to enable GEM3 network 
device we must need to give following full command line options

-net nic -net nic -net nic -net nic -net user, ...

In this way all four GEM devices would be enable but first three 
GEM0-GEM2 devices are un-configured and useless. In our case QEMU is 
being *crashed* due to trying to use these un-configured GEM devices to 
o send/receive GDB breakoint/interrupt cause. IIUC QEMU uses first 
device in the -nic loop
i.e

qemu-system-aarch64: hw/net/cadence_gem.c:921: gem_receive: Assertion 
`!first_desc' failed.



My question is that, is there a way in QEMU to only select/enable GEM3 
device while other don't use in emulation ?


If there is no such option to select specific device then what do you 
thing, this shouldn't be in qemu?



Thanks,
-Bilal