1Normally, a minimal initrd is created automatically by the rcutorture 2scripting. But minimal really does mean "minimal", namely just a single 3root directory with a single statically linked executable named "init": 4 5$ size tools/testing/selftests/rcutorture/initrd/init 6 text data bss dec hex filename 7 328 0 8 336 150 tools/testing/selftests/rcutorture/initrd/init 8 9Suppose you need to run some scripts, perhaps to monitor or control 10some aspect of the rcutorture testing. This will require a more fully 11filled-out userspace, perhaps containing libraries, executables for 12the shell and other utilities, and soforth. In that case, place your 13desired filesystem here: 14 15 tools/testing/selftests/rcutorture/initrd 16 17For example, your tools/testing/selftests/rcutorture/initrd/init might 18be a script that does any needed mount operations and starts whatever 19scripts need starting to properly monitor or control your testing. 20The next rcutorture build will then incorporate this filesystem into 21the kernel image that is passed to qemu. 22 23Or maybe you need a real root filesystem for some reason, in which case 24please read on! 25 26The remainder of this document describes one way to create the 27rcu-test-image file that contains the filesystem used by the guest-OS 28kernel. There are probably much better ways of doing this, and this 29filesystem could no doubt be smaller. It is probably also possible to 30simply download an appropriate image from any number of places. 31 32That said, here are the commands: 33 34------------------------------------------------------------------------ 35dd if=/dev/zero of=rcu-test-image bs=400M count=1 36mkfs.ext3 ./rcu-test-image 37sudo mount -o loop ./rcu-test-image /mnt 38 39# Replace "precise" below with your favorite Ubuntu release. 40# Empirical evidence says this image will work for 64-bit, but... 41# Note that debootstrap does take a few minutes to run. Or longer. 42sudo debootstrap --verbose --arch i386 precise /mnt http://archive.ubuntu.com/ubuntu 43cat << '___EOF___' | sudo dd of=/mnt/etc/fstab 44# UNCONFIGURED FSTAB FOR BASE SYSTEM 45# 46/dev/vda / ext3 defaults 1 1 47dev /dev tmpfs rw 0 0 48tmpfs /dev/shm tmpfs defaults 0 0 49devpts /dev/pts devpts gid=5,mode=620 0 0 50sysfs /sys sysfs defaults 0 0 51proc /proc proc defaults 0 0 52___EOF___ 53sudo umount /mnt 54------------------------------------------------------------------------ 55 56 57References: 58 59 http://sripathikodi.blogspot.com/2010/02/creating-kvm-bootable-fedora-system.html 60 https://help.ubuntu.com/community/KVM/CreateGuests 61 https://help.ubuntu.com/community/JeOSVMBuilder 62 http://wiki.libvirt.org/page/UbuntuKVMWalkthrough 63 http://www.moe.co.uk/2011/01/07/pci_add_option_rom-failed-to-find-romfile-pxe-rtl8139-bin/ -- "apt-get install kvm-pxe" 64 https://www.landley.net/writing/rootfs-howto.html 65 https://en.wikipedia.org/wiki/Initrd 66 https://en.wikipedia.org/wiki/Cpio 67 http://wiki.libvirt.org/page/UbuntuKVMWalkthrough 68