Re: [Qemu-discuss] multiple nic interfaces question

[Medi Montaseri]

I have made some progress...

I was looking for a way of adding multiple interfaces, I learned that 
there exists a runqemu-gen-tapdevs(1) that was designed just for that. 
It reads

# Create a "bank" of tap network devices that can be used by the
# runqemu script. This script needs to be run as root, and will
# use the tunctl binary from the build system sysroot.

So equipped with that, I modify my script to say

echo "=== Deleteing existing taps..."
sudo $RUNQEMU_GEN_TAPDEVS  $myID $myGID 0 $OECORE_NATIVE_SYSROOT
echo "=== Creating $ifcnt taps..."
sudo $RUNQEMU_GEN_TAPDEVS  $myID $myGID $ifcnt $OECORE_NATIVE_SYSROOT
netConf=" -netdev tap,id=net0,ifname=tap0 -device virtio-net-pci,netdev=net0 "
cmd+=" qemuparams=\"-m $memory $qemu_virtio_params $netConf\""
eval $cmd

And I get the following....

...skip...

=== Deleteing existing taps...
Note: Destroying pre-existing tap interface tap0...
Set 'tap0' nonpersistent
Creating 0 tap devices for UID: 1000 GID: 1000...
=== Creating 1 taps...
Creating 1 tap devices for UID: 1000 GID: 1000...
Creating tap0

...skip..

Acquiring lockfile for tap0...
Using preconfigured tap device 'tap0'
....skip....
RTNETLINK answers: Operation not permitted
W: /etc/qemu-ifup: no bridge for guest interface found
qemu-system-x86_64: -net tap,vlan=0,ifname=tap0,script=no,downscript=no: could 
not configure /dev/net/tun (tap0): Device or resource busy
Releasing lockfile of preconfigured tap device 'tap0'

Do I need to chase the bridge issue ? or Device or resource busy issue

Thanks

Medi



On 12/18/2017 07:16 PM, Medi Montaseri wrote:
> Hi,
>
> I am trying to configure multiple nic interfaces and having some 
> problems, help is appreciated.
>
> my runqemu(1) script from poky/scripts/runqemeu is
>
> commit 1db3dc88036ccd46ed2b714fdc0fb565beb001ed
> Author: Robert Yang <address@hidden>
> Date:   Sun Apr 10 07:16:48 2016 -0700
>
> I have been using it successfully like
>
> About to run [runqemu  qemux86-64  serial  kvm  qemuparams="-m 256  
> -device virtio-serial  -chardev 
> socket,path=./virtio-ports/tty0,server,nowait,id=tty0   -device 
> virtserialport,chardev=tty0,name=tty0    "]
>
> I notice that it is creating tap0 and then cleans it up (a transient 
> tap device).
>
> runqemu(1) in-turn is calling
>
> build/tmp-glibc/sysroots/x86_64-linux/usr/bin/qemu-system-x86_64
>    -kernel 
> /home/medim/work3/build/tmp-glibc/deploy/images/qemux86-64/bzImage-qemux86-64.bin
>    -net nic,model=virtio -net 
> tap,vlan=0,ifname=tap0,script=no,downscript=no
>    -cpu kvm64 -drive 
> file=/home/medim/work3/build/tmp-glibc/deploy/images/qemux86-64/og-image-consoleserver-dev-qemux86-64-20171218190955.rootfs.ext4,if=virtio,format=raw
>    -show-cursor -usb -usbdevice tablet -vga vmware -no-reboot -serial 
> stdio -enable-kvm -m 256
>     -device virtio-serial -chardev 
> socket,path=./virtio-ports/tty0,server,nowait,id=tty0
>     -device virtserialport,chardev=tty0,name=tty0
>     -append "vga=0 uvesafb.mode_option=640x480-32 root=/dev/vda rw 
> mem=256M ip=192.168.7.2::192.168.7.1:255.255.255.0 oprofile.timer=1 
> rootfstype=ext4 console=ttyS0"
>
> As seen, we have one tap0 device. I would like to create multiple tap 
> devices (say tap1, tap2, etc). I have tried adding the following to 
> qemuparams
>
> case 1: " -net nic,model=virtio -net tap,ifname=tap1,script=no"
> case 2: " -netdev tap,id=net0,ifname=tap1 -device 
> virtio-net-pci,netdev=net0 "
> case 3: " -net none -netdev tap,id=net0,ifname=tap1 -device 
> virtio-net-pci,netdev=net0 "
>
> And always get the following error
> qemu-system-x86_64: -netdev tap,id=net0,ifname=tap1: could not 
> configure /dev/net/tun (tap1): Operation not permitted
> Set 'tap0' nonpersistent
> Releasing lockfile of preconfigured tap device 'tap0'
>
> /dev/net/tun mode is
>
> ls -ld /dev/net/tun
> crw-rw-rw- 1 root root 10, 200 Dec 11 16:20 /dev/net/tun
>
> there is a sudo operation going on by someone (but I can't tell by who 
> or when)....
>
> Continuing with the following parameters:
> KERNEL: 
> [/home/medim/work3/build/tmp-glibc/deploy/images/qemux86-64/bzImage-qemux86-64.bin]
> ROOTFS: 
> [/home/medim/work3/build/tmp-glibc/deploy/images/qemux86-64/og-image-consoleserver-dev-qemux86-64-20171218190955.rootfs.ext4]
> FSTYPE: [ext4]
> Setting up tap interface under sudoAcquiring lockfile for tap0...
>
> Anyways, I have the following questions:
>
> 1- Can I mix -net and -netdev together. Looks like -net is deprecated
>
> 2- Say I want to have persistent devices, how to instruct runqemu(1) 
> or qemu-system-x86_64(1) to stay away from tap creation, and use 
> existing persistent taps.
>
> 3- Do you have any suggestions as how to fix this issue.
>
>
> Thans
>
> Medi