qemu network emulation

vishesh · 03-23-2009, 03:39 AM

Dear all

From past two days i trying to ping my host from running guest on qemu.
Both host and guest is fedora 9. Network emulation on guest os require tap0 interface that is not present on my host. I know that i am not getting the point correctly, where i am doing mistake?
how i can bridge my eth0 with virtual tap0, when tap0 is not present.

Thanks

reptiler · 03-23-2009, 03:43 AM

Did you check using ifconfig -a if it's maybe there but not active.

Also, maybe you'd like to give virt-manager a try. It makes all this VM-related stuff a lot easier.

vishesh · 03-23-2009, 04:12 AM

Thanks for reply

Quote:

Originally Posted by reptiler

Did you check using ifconfig -a if it's maybe there but not active.

Yes i already tried 'ifconfig -a' i only list eth0,lo,pan0 and virbr0

reptiler · 03-23-2009, 04:27 AM

pan0 is, if I'm not totally off, Bluetooth-related.
virbr0 is VM-related, as it is established by LibVirt.

As said, try virt-manager, it'll be a lot easier.
I guess you're working in a GUI, right?

Ever since I switched to Fedora I used virt-manager, because I was simply sick of having these damn long command-lines for QEmu all the time.

As an alternative you can have what virt-manager offers you in the shell, using virsh, virt-install and so on.

Edit: Just tried this (as root):

Code:

qemu-kvm -net nic -net tap,script=no -cdrom Slackware-12.1.iso -boot d

And it does create a device tap0.

quantt · 03-24-2009, 04:37 AM

Hello everyone!
I tried boot my image, but qemu just waiting something. I didn't seen whatever in stdio, why?

Code:

#qemu -m 256 -net nic -net tap,ifname=tap0 -hda netbsd.img -nographic -localtime -no-acpi

I use kernel qemu

Code:

# lsmod | grep kqemu
kqemu                 129444  0
# ls /dev/kqemu
/dev/kqemu

qemu-0.10.0
kqemu-1.4.0pre1
To prepare I made two images via mkdisk.sh.
http://koowaldah.org/people/ash/netbsd/mkdisk.sh

p.s. "And it does create a device tap0."
You needs to create tap0 by your hands via tunctl in linux.

reptiler · 03-24-2009, 04:58 AM

Quote:

Originally Posted by quantt

I tried boot my image, but qemu just waiting something. I didn't seen whatever in stdio, why?

If everything is okay QEmu will not output anything to the shell.
If you want to be able to interact with the VM on the shell I suggest appending -monitor stdio to your list of parameters.

Quote:

Originally Posted by quantt

You needs to create tap0 by your hands via tunctl in linux.

No, I didn't need to do this manually. I used to do it as shown above on LFS and just for this thread tested it on Fedora 10. I did not have to create the tap-device, QEmu did this for me.
Of course you need to be root for that.

quantt · 03-24-2009, 10:20 AM

Quote:

If everything is okay QEmu will not output anything to the shell.
If you want to be able to interact with the VM on the shell I suggest appending -monitor stdio to your list of parameters.

hm. but if I launching that like this, qemu do nothing events somewhere.
qemu -m 256 -hda netbsd.img -nographic -localtime -no-acpi -boot d -monitor stdio
furthermore, it is not eating cpu capacity.
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
23455 root 20 0 382m 9.8m 1596 S 0 0.1 0:00.18 qemu

reptiler · 03-24-2009, 10:27 AM

Do you have a GUI available on that machine that you could start QEmu with a window and then see if it actually can boot.
Maybe it tries to boot but cannot for some reason which would only the visible in the VM's window, and thus is not eating up much CPU.

quantt · 03-25-2009, 05:10 AM

What's a window? Did you mean its like kde konsole or something else?

reptiler · 03-25-2009, 05:36 AM

A GUI-window, similar to other windows you may be used to from GUIs, like the Firefox-window, or your filemanager's window.

There QEmu will show the boot-process and the whatever the system is supposed to show, just like when you boot up your PC.