1*4882a593SmuzhiyunNormally, a minimal initrd is created automatically by the rcutorture 2*4882a593Smuzhiyunscripting. But minimal really does mean "minimal", namely just a single 3*4882a593Smuzhiyunroot directory with a single statically linked executable named "init": 4*4882a593Smuzhiyun 5*4882a593Smuzhiyun$ size tools/testing/selftests/rcutorture/initrd/init 6*4882a593Smuzhiyun text data bss dec hex filename 7*4882a593Smuzhiyun 328 0 8 336 150 tools/testing/selftests/rcutorture/initrd/init 8*4882a593Smuzhiyun 9*4882a593SmuzhiyunSuppose you need to run some scripts, perhaps to monitor or control 10*4882a593Smuzhiyunsome aspect of the rcutorture testing. This will require a more fully 11*4882a593Smuzhiyunfilled-out userspace, perhaps containing libraries, executables for 12*4882a593Smuzhiyunthe shell and other utilities, and soforth. In that case, place your 13*4882a593Smuzhiyundesired filesystem here: 14*4882a593Smuzhiyun 15*4882a593Smuzhiyun tools/testing/selftests/rcutorture/initrd 16*4882a593Smuzhiyun 17*4882a593SmuzhiyunFor example, your tools/testing/selftests/rcutorture/initrd/init might 18*4882a593Smuzhiyunbe a script that does any needed mount operations and starts whatever 19*4882a593Smuzhiyunscripts need starting to properly monitor or control your testing. 20*4882a593SmuzhiyunThe next rcutorture build will then incorporate this filesystem into 21*4882a593Smuzhiyunthe kernel image that is passed to qemu. 22*4882a593Smuzhiyun 23*4882a593SmuzhiyunOr maybe you need a real root filesystem for some reason, in which case 24*4882a593Smuzhiyunplease read on! 25*4882a593Smuzhiyun 26*4882a593SmuzhiyunThe remainder of this document describes one way to create the 27*4882a593Smuzhiyunrcu-test-image file that contains the filesystem used by the guest-OS 28*4882a593Smuzhiyunkernel. There are probably much better ways of doing this, and this 29*4882a593Smuzhiyunfilesystem could no doubt be smaller. It is probably also possible to 30*4882a593Smuzhiyunsimply download an appropriate image from any number of places. 31*4882a593Smuzhiyun 32*4882a593SmuzhiyunThat said, here are the commands: 33*4882a593Smuzhiyun 34*4882a593Smuzhiyun------------------------------------------------------------------------ 35*4882a593Smuzhiyundd if=/dev/zero of=rcu-test-image bs=400M count=1 36*4882a593Smuzhiyunmkfs.ext3 ./rcu-test-image 37*4882a593Smuzhiyunsudo mount -o loop ./rcu-test-image /mnt 38*4882a593Smuzhiyun 39*4882a593Smuzhiyun# Replace "precise" below with your favorite Ubuntu release. 40*4882a593Smuzhiyun# Empirical evidence says this image will work for 64-bit, but... 41*4882a593Smuzhiyun# Note that debootstrap does take a few minutes to run. Or longer. 42*4882a593Smuzhiyunsudo debootstrap --verbose --arch i386 precise /mnt http://archive.ubuntu.com/ubuntu 43*4882a593Smuzhiyuncat << '___EOF___' | sudo dd of=/mnt/etc/fstab 44*4882a593Smuzhiyun# UNCONFIGURED FSTAB FOR BASE SYSTEM 45*4882a593Smuzhiyun# 46*4882a593Smuzhiyun/dev/vda / ext3 defaults 1 1 47*4882a593Smuzhiyundev /dev tmpfs rw 0 0 48*4882a593Smuzhiyuntmpfs /dev/shm tmpfs defaults 0 0 49*4882a593Smuzhiyundevpts /dev/pts devpts gid=5,mode=620 0 0 50*4882a593Smuzhiyunsysfs /sys sysfs defaults 0 0 51*4882a593Smuzhiyunproc /proc proc defaults 0 0 52*4882a593Smuzhiyun___EOF___ 53*4882a593Smuzhiyunsudo umount /mnt 54*4882a593Smuzhiyun------------------------------------------------------------------------ 55*4882a593Smuzhiyun 56*4882a593Smuzhiyun 57*4882a593SmuzhiyunReferences: 58*4882a593Smuzhiyun 59*4882a593Smuzhiyun http://sripathikodi.blogspot.com/2010/02/creating-kvm-bootable-fedora-system.html 60*4882a593Smuzhiyun https://help.ubuntu.com/community/KVM/CreateGuests 61*4882a593Smuzhiyun https://help.ubuntu.com/community/JeOSVMBuilder 62*4882a593Smuzhiyun http://wiki.libvirt.org/page/UbuntuKVMWalkthrough 63*4882a593Smuzhiyun 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*4882a593Smuzhiyun https://www.landley.net/writing/rootfs-howto.html 65*4882a593Smuzhiyun https://en.wikipedia.org/wiki/Initrd 66*4882a593Smuzhiyun https://en.wikipedia.org/wiki/Cpio 67*4882a593Smuzhiyun http://wiki.libvirt.org/page/UbuntuKVMWalkthrough 68