Buildroot QEMU Cortex A7 configuration

This is a buildroot configuration for emulating a system with ARM Cortex A7 core on the virt platform. The setup is designed as a test runner or debug system and goes beyond the minimal buildroot configuration. This includes

• ssh access as root
• gbd setup (planned)

Usage

Clone the buildroot repository

git clone https://git.busybox.net/buildroot

and this repository so they sit on the same level.

git clone https://github.com/dlips/br_qemu_cortex_a7.git

Then switch to the buildroot directory with cd buildroot and create a new defconfig using br_qemu_cortex_a7 as BR2_EXTERNAL (see documentation)

make BR2_EXTERNAL=../br_qemu_cortex_a7 O=../my_br_build qemu_cortex_a7_defconfig

Afterwards you can customize the image with

make O=../my_br_build menuconfig

and then build the system running

make O=../my_br_build

Commands

QEMU

• Start QEMU from the images folder using

  qemu-system-arm \
      -M virt \
      -cpu cortex-a7 \
      -m 256 \
      -kernel zImage \
      -drive file=rootfs.ext2,if=none,format=raw,id=hd0 \
      -device virtio-blk-device,drive=hd0 \
      -nographic \
      -no-reboot \
      -append "rootwait root=/dev/vda console=ttyAMA0" \
      -device virtio-net-device,netdev=net0 \
      -netdev user,id=net0,hostfwd=tcp::5555-:22
  

  Here we us the globally installed qemu-system-arm, but buildroot is also configured to build QEMU as host utility. If you want to use this version instead or QEMU is not installed globally, replace qemu-system-arm with ../host/bin/qemu-system-arm

• Shutdown in guest system: Start guest with -no-reboot option and then in the guest you can run poweroff

• Manually bring up network in guest system

  ifconfig eth0 10.0.2.15 netmask 255.255.255.0
  route add default gw 10.0.2.2
  echo "nameserver 8.8.8.8" > /etc/resolv.conf