[Buildroot] 3. Re: Buildroot How-To for QEMU/ARM

[Vellemans, Noel]

Re: Buildroot How-To for QEMU/ARM (Jim Thomas) 
Jim >>Hi Noel,
Jim >>
Jim >>  > If you want I can send you a kernel config ... that is working
for my
Jim >>  > QEMU build (it is based on the kernel versatile_defconfig).
Jim >>
Jim >>I would be interested in looking over your .config file.

Please Find the enclosed kernel config.

Jim >>I think what I am missing may be on the QEMU side, not the
Buildroot side.

Jim >>What qemu-system-arm command do you use to bring up your virtual
machine?
Jim >>
Jim >>

As said before : Booting the kernel and rootfs in QEMU can be done by a
1000ways, it depends on your creativity and Linux-skills how you do this
(disk-image/ nfs-boot / .... etc ) 

But I often use the following command line: 

sudo qemu-system-arm -M versatilepb -net nic,vlan=0 -append
"root=/dev/nfs rw nfsroot=192.168.205.4:/nfsroot/emuroot
ip=192.168.204.147:192.168.205.4:192.168.204.1:255.255.254.0" -net
tap,ifname=tap0,script=/etc/qemu-ifup --kernel zImage-20100128

This requires some more info ... so, (very) sort.... QEMU via NFS !

NOTE: I think I have read somewhere you where running ubuntu... (hope
this is correct)

1) Install bridge-utils
sudo apt-get install bridge-utils

2) Make sure you have a working NFSserver ( in my case 192.168.205.4)
Install NFS Server Support

sudo apt-get install nfs-kernel-server nfs-common portmap

When configuring portmap do =not= bind loopback. If you do you can
either edit /etc/default/portmap by hand or run:
sudo dpkg-reconfigure portmap
sudo /etc/init.d/portmap restart

Editing /etc/exports
the /etc/exports file is used for creating a share on the NFS server

invoke your favorite text editor or
sudo vi /etc/exports
or
sudo gedit /etc/exports

Here is quick example of what you could add to your /etc/exports

/nfsroot/emuroot *(rw,async,no_subtree_check)

Make sure you have your tun/ tap installed.
To install TUN/TAP: 
sudo apt-get install uml-utilities

Activate tap0
sudo tunctl -t tap0 sudo tunctl -t tap0


Create a script call /etc/qemu-ifup that will be executed upon the start
of QEMU: 
#!/bin/sh 
echo "Executing /etc/qemu-ifup" 
echo "Bringing up $1 for bridged mode..." 
sudo /sbin/ifconfig $1 0.0.0.0 promisc up 
echo "Adding $1 to br0..." 
sudo /usr/sbin/brctl addif br0 $1 
sleep 2 


start QEMU as super user :
 
sudo qemu-system-arm -M versatilepb -net nic,vlan=0 -append
"root=/dev/nfs rw nfsroot=192.168.205.4:/nfsroot/emuroot
ip=192.168.204.147:192.168.205.4:192.168.204.1:255.255.254.0" -net
tap,ifname=tap0,script=/etc/qemu-ifup --kernel zImage-20100128


Regards Noel.
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