Tuesday, January 14, 2014

Netboot EFI Linux (diskless) with qemu/ovmf/grub2

. prerequiresites:

- DHCP/TFTP, so that you can netboot with PXE;

1) create an standalone grub efi image:

  sudo grub2-mkstandalone -d /usr/lib/grub/x86_64-efi/ -O x86_64-efi --fonts="unicode" -o grub2.efi  /boot/grub/grub.cfg=/tftpboot/netgrub.cfg

netgrub.cfg is something like:

 set timeout=5

# linux (tftp)/vmlinuz
menuentry 'Linux diskless' --class gentoo --class gnu-linux --class gnu --class os {
        insmod net
        insmod efinet
        insmod tftp
        insmod http
        insmod gzio
        insmod part_gpt

        insmod efi_gop
        insmod efi_uga

        set net_default_server=

        net_add_addr eno0 efinet0

        echo 'Network status: '

        echo 'Loading Linux ...'
        linux (tftp)/vmlinuz root=/dev/nfs rw nfsroot= ip=on

and let DHCP server send grub2.efi (filename=grub2.efi) to our client (

2) build OVMF from EDK2.

3) running a recent qemu (>= 1.6.0)

  sudo qemu-system-x86_64 -enable-kvm -m 2048 -vga qxl -L . -bios OVMF.fd -device virtio-net-pci,romfile=,netdev=mynet0,mac=00:12:34:56:78:9a -netdev tap,script=/etc/qemu/qemu-ifup,id=mynet0 -vnc :30

- Because we use macaddr above, need make sure DHCP server configure macaddr from above to ip address
- Make sure romfile is empty, which will use OVMF virtio-net-pci driver instead of iPXE virtio-net-pci driver (in my case it runs into error: failure at drivers/bus/virtio-ring.c:69)

4) vncview :30 and check status.


a) In theory this can also boot a box supports PXE into EFI mode (diskless), so that you don't have to create a EFI boot disk (I don't like this way).

dmesg from booted linux with above method:


Wednesday, March 4, 2009

Install Debian testing/lenny into Qemu MIPS Malta board

Install Debian testing/lenny into Qemu MIPS Malta board

1. Install debian (testing/lenny) with qemu-system-mipsel/malta.

qemu-img create -f qcow2 debian-mipsel.img 1G
lftp -c mirror ftp://ftp.fi.debian.org/debian/dists/testing/main/installer-mipsel/current/images/malta/netboot/
cd netboot
sudo qemu-system-mipsel -kernel vmlinux-2.6.26-1-4kc-malta -initrd initrd.gz -append 'console=ttyS0' -nographic -serial stdio -net nic -net tap -hda /path/to/debian-mipsel.img

Fellow the standard debian installation process and finish install debian (standard system) to debian-mipsel.img.
Note: Qemu emulation for architecture different from the host side is very slow, be patient during the installation. this maybe take more than 1 hrs depending on the host's hardware configuration.

2. Reboot to the debian-mipsel system we installed right now, rsyncing the entire file system if neccessary (in case of nfsroot). Before that, we'd better to build our own kernel. the qemu simulates MIPS MALTA board with the following hardware:

The Malta emulation supports the following devices:

* - Core board with MIPS 24Kf CPU and Galileo system controller
* - PIIX4 PCI/USB/SMbus controller
* - The Multi-I/O chip's serial device
* - PCnet32 PCI network card
* - Malta FPGA serial device
* - Cirrus VGA graphics card

compile kernel for mips malta board:

cd linux-2.6
make ARCH=mips malta_defconfig

Tune the defconfig if needed:

make ARCH=mips menuconfig
make ARCH=mips CROSS_COMPILE=mipsel-unknown-linux-gnu- -j3

After we have own own kernel, we could use this kernel to boot with our filesystem we installed right now:

sudo qemu-system-mipsel -kernel vmlinux -append 'root=/dev/hda1 ro console=ttyS0' -nographic -serial stdio -net nic -net tap -hda /path/to/debian-mipsel.img -boot c

Login into the new system, prepare to exports our filesystem using rsync:

aptitude update
aptitude install rsync

Since the `/' filesystem contains some virtual filesystem like /dev, /proc, /sys, we must avoid syncing these directory, and the simplest way I know is:

Mount the root filesystem to other directory:

mount /dev/hda1 /mnt

Mount other directory like /boot to the new mounted root (/mnt) if neccessary.

On a other machine, assume it's IP address is

sudo mkdir -p /exports/nfs/diskless/debian-mipsel # on, choose a directory you prefer.

On our Qemu target:

cd /mnt
rsync -av * root@ # sync the entire filesystem to the remote machine.

Note 1: We use qemu to `cheat' for a filesystem installed with debian, in a simular way we could also have a rootfs for other architecture.
Note 2: Other than Debian, gentoo stage3 is also a good choice, and you don't have to install (with qemu-system-xxx), but surely you don't want to `emerge' in a qemu simluated target system ;-)
Note 3: If you have a debian host environment, the simplest way to install a rootfs might be use debootstrap, you can also debootstrap a filesystem for other architecture, please refer to `man debootstrap' for details.

3. Using Qemu/MALTA with nfsroot. Before that we have to modify the something in the nfsroot filesystem, ie:

cd /exports/nfs/diskless/debian-mipsel

vim etc/fstab # comment stuff like /dev/hda1 etc..
vim etc/inittab # comment tty* since we don't use any tty and uncomment ttyS0 and use a proper bitrate because our terminal is on ttyS0

cd /path/to/linux-2.6
sudo qemu-system-mipsel -kernel vmlinux -append 'root=/dev/nfs rw nfsroot= ip=dhcp console=ttyS0' -nographic -serial stdio -net nic -net tap

Note: to use this, make sure DHCP and NFS server is configured properly, please refer to this document: http://wangbj.blogspot.com/2009/03/using-qemu-to-simulate-armintegratorcp.html or /usr/src/linux/Documentation/filesystem/nfsroot.txt (the best).

Monday, March 2, 2009

Using Qemu to simulate ARM/IntegratorCP board

Using Qemu to simulate ARM/IntegratorCP board

1. Qemu/u-boot setup.

Get a recent copy of u-boot sources, build for integrator board.

cd u-boot-2009.01
make integratorcp_config
make ARCH=arm CROSS_COMPILE=arm-unknown-linux-gnueabi-

Now we could use qemu to run u-boot binary. ie:

qemu-system-arm -kernel u-boot -net nic -net tap -nographic -serial stdio

Note: we should have -net nic -net tap support, otherwise u-boot will not able to do network traffic.

2. Compile a kernel for IntegratorCP board.

cd linux-2.6
make ARCH=arm integrator_defconfig

tune settings to fit the IntergratorCP board, Qemu simulates this board with (from /usr/share/doc/qemu-xxx):

Use the executable 'qemu-system-arm' to simulate a ARM machine. The ARM Integrator/CP board is emulated with the following devices:

* - ARM926E, ARM1026E, ARM946E, ARM1136 or Cortex-A8 CPU
* - Two PL011 UARTs
* - SMC 91c111 Ethernet adapter
* - PL110 LCD controller
* - PL050 KMI with PS/2 keyboard and mouse.
* - PL181 MultiMedia Card Interface with SD card.

Note: ARM926E is an ARMv5te architecture.

make ARCH=arm menuconfig
make ARCH=arm CROSS_COMPILE=arm-unknown-linux-gnueabi- -j3
make ARCH=arm CROSS_COMPILE=arm-unknown-linux-gnueabi- uImage

3. Qemu, u-boot, and kernel together.

copy our uImage to tftp server, configure an tftp server first if you don't have one.

cp arch/arm/boot/uImage /tftpboot/uImage
/etc/init.d/in.tftpd start

run qemu with u-boot

qemu-system-arm -kernel ~/build/u-boot/u-boot-2009.01/u-boot -net nic -net tap -nographic -serial stdio

and then under u-boot prompt:

Integrator-CP # setenv ipaddr # board ip address
Integrator-CP # setenv server # tftp server ipaddress
Integrator-CP # setenv bootargs 'root=/dev/nfs rw nfsroot= ip=dhcp console=ttyAMA0'
Integrator-CP # tftp 400000 uImage
Integrator-CP # bootm 400000

Note 1: I'm using nfs-root/diskless system, to use this, you have to configure a nfs server first, the corresponding /etc/exports file should be something like:

# /etc/exports: NFS file systems being exported. See exports(5).


Note 2: /exports/nfs/diskless/gentoo-arm is a filesystem from gentoo/arm stage3 tarball, since we're using IP kernel level autoconfigration, so we have to tell the userspace program do not to configure ip anymore, under gentoo system, this could be done by (/etc/conf.d/net):

config_eth0=( "null" );

Change /etc/inittab so that init could start from ttyAMA0 with proper bitrate. you can also uncomment tty0-tty6 since we don't use them.

By default the init program is also trying to mount /etc/fstab entries, we could also uncomment unneccessary entries to avoid mount errors/warnings.

Note 3: The cross-toolchain is built by gentoo's crossdev by:

crossdev -S --ex-gdb -t arm-unknown-linux-gnueabi

Friday, February 20, 2009

Using kvm/qemu with virtio

Using kvm/qemu with virtio

Since kernel 2.6.25, linux kernel have virtio support, virtio is different
with full device virtualization, it doesn't have to behave as the realhardware,
the guest driver actually knows it is running under a virtual environment, thus
in theory it's should be faster and more efficient than the full virtualized

Newer qemu (svn version, not 0.9.1) have virtio support, recent kvm also have
virtio support.

In order to utilize virtio, you will need a recent kernel (> 2.6.25) with
virtio (variants) support, and a recent qemu/kvm.

How to use Virtio

* Get kvm version >= 60 (or recent svn verstion qemu)
* Get Linux kernel with virtio drivers for the guest

Get Kernel >= 2.6.25 and activate (modules should also work, but take care of initramdisk)

CONFIG_VIRTIO_PCI=y (Virtualization -> PCI driver for virtio devices)

CONFIG_VIRTIO_BALLOON=y (Virtualization -> Virtio balloon driver)

CONFIG_VIRTIO_BLK=y (Device Drivers -> Block -> Virtio block driver)

CONFIG_VIRTIO_NET=y (Device Drivers -> Network device support -> Virtio network driver)
+ CONFIG_VIRTIO=y (automatically selected)
+ CONFIG_VIRTIO_RING=y (automatically selected)
+ you can safely disable SATA/SCSI and also all other nic drivers if you only use VIRTIO (disk/nic)

As an alternative one can use a standard guest kernel for the guest > 2.6.18 and make use sync backward compatibility option

Backport and instructions can be found in kvm-guest-drivers-linux.git
* Use model=virtio for the network devices and if=virtio for disk

qemu/x86_64-softmmu/qemu-system-x86_64 -boot c -drive file=/images/xpbase.qcow2,if=virtio,boot=on -m 384 -net nic,model=virtio -net tap,script=/etc/kvm/qemu-ifup

Another Example of using virtio:

I use qemu/kvm to install a distro like arch linux, I can't use virtio at the
begining because the official arch linux kernel (archlinux 2009.2, kernel can not boot via virtio devices. so:

qemu-img create -f qcow2 arch-x86.img 1G
sudo kvm -cdrom archlinux-2009.02-core-x86_64.iso -hda arch-x86.img -boot 'd' -net nic,model=e1000 -net tap

NOTE: root partition mount point in /etc/fstab should be UUID or LABEL based
because later the device interface (sda->vda) might be changed. ie:

LABEL=/arch / ext4 noatime 0 0

after finishing archlinux installation, we could use our own kernel to utilize
virtio, ie:

cd ~/linux/linux-2.6

build a kernel with VIRTIO support.

sudo kvm -kernel arch/i386/boot/bzImage -append 'root=/dev/vd1 ro console=ttyS0,115200' -drive file=~/arch-x86.img,if=virtio,boot=on -m 256 -net nic,model=virtio -net tap


Thursday, February 19, 2009

Gentoo QEMU/KVM ethernet bridging nano HOWTO

Qemu could use tun/tap to emulate bridged network, so the guest could have a real ip as host. ie:

[code]qemu -net nic -net tap[/code]


[code]kvm -net nic -net tap[/code]

Under gentoo, in order to use that, we have to:

* kernel requirements:

CONFIG_BRIDGE, CONFIG_TUN must be included (y/m) CONFIG_KVM_INTEL/CONFIG_KVM_AMD must be selected in order to use kvm

CONFIG_IP_PNP and CONFIG_ROOT_NFS must be included to use nfsroot/diskless mounted filesystem. Host side NIC driver must also be compiled into kernel (y).

* user space application:

bridge-utils, qemu/kvm

Networking interface layout:

br0: bridge interface, binded with real IP address for network access. eth0: interface of br0, no IP. tapX: interface of guest, no IP.

NOTE: switch interfaces don't have an IP address.

Network configuration in gentoo:

*) make sure NetworkManager/dhcdbd is not started, network interface must not be managed by NetworkManager. ie:


$ cd /etc/init.d/ $ ln -s net.lo net.eth0 $ ln -s net.lo net.br0 $ rc-update add net.eth0 default $ rc-update add net.br0 default


*) /etc/conf.d/net configration, ie:


bridge_br0="eth0" config_br0=("dhcp") config_eth0=("null")


You have to insert some modules if neccessary like:


$ modprobe tun kvm_amd


Start using qemu/kvm:


$ kvm -kernel bzImage -append "root=/dev/nfs rw nfsroot=192.168.2.xxx:/home/gentoo-x86 ip=on" -net nic,model=e1000 -net tap


Note: kvm have it's own network startup/stop scripts /etc/kvm/kvm-if{up,down} in gentoo, if you're using qemu, you have to write your own /etc/qemu-if{up,down} scripts, just copying /etc/kvm/kvm-if{up,down} it's essential.


http://www.linuxfoundation.org/en/Net:Bridge gentoo's /etc/conf.d/net.example

1st post of my blog ;)

very happy to become a blogger ;-)