Re: [PATCH] KVM: Add wrapper script around QEMU to test kernels

Alexander Graf
2012-05-11T13:43:45Z

On 06.11.2011, at 14:54, Jan Kiszka wrote:

> On 2011-08-24 23:38, Alexander Graf wrote:
>> On LinuxCon I had a nice chat with Linus on what he thinks kvm-tool
>> would be doing and what he expects from it. Basically he wants a
>> small and simple tool he and other developers can run to try out and
>> see if the kernel they just built actually works.
>>
>> Fortunately, QEMU can do that today already! The only piece that was
>> missing was the "simple" piece of the equation, so here is a script
>> that wraps around QEMU and executes a kernel you just built.
>>
>> If you do have KVM around and are not cross-compiling, it will use
>> KVM. But if you don't, you can still fall back to emulation mode and
>> at least check if your kernel still does what you expect. I only
>> implemented support for s390x and ppc there, but it's easily extensible
>> to more platforms, as QEMU can emulate (and virtualize) pretty much
>> any platform out there.
>>
>> If you don't have qemu installed, please do so before using this script. Your
>> distro should provide a package for it (might even call it "kvm"). If not,
>> just compile it from source - it's not hard!
>>
>> To quickly get going, just execute the following as user:
>>
>> $ ./Documentation/run-qemu.sh -r / -a init=/bin/bash
>>
>> This will drop you into a shell on your rootfs.
>>
>> Happy hacking!
>>
>> Signed-off-by: Alexander Graf <agraf@suse.de>
>>
>> ---
>>
>> v1 -> v2:
>>
>> - fix naming of QEMU
>> - use grep -q for has_config
>> - support multiple -a args
>> - spawn gdb on execution
>> - pass through qemu options
>> - dont use qemu-system-x86_64 on i386
>> - add funny sentence to startup text
>> - more helpful error messages
>> ---
>> scripts/run-qemu.sh | 334 +++++++++++++++++++++++++++++++++++++++++++++++++++
>> 1 files changed, 334 insertions(+), 0 deletions(-)
>> create mode 100755 scripts/run-qemu.sh
>>
>> diff --git a/scripts/run-qemu.sh b/scripts/run-qemu.sh
>> new file mode 100755
>> index 0000000..5d4e185
>> --- /dev/null
>> +++ b/scripts/run-qemu.sh
>> @@ -0,0 +1,334 @@
>> +#!/bin/bash
>> +#
>> +# QEMU Launcher
>> +#
>> +# This script enables simple use of the KVM and QEMU tool stack for
>> +# easy kernel testing. It allows to pass either a host directory to
>> +# the guest or a disk image. Example usage:
>> +#
>> +# Run the host root fs inside a VM:
>> +#
>> +# $ ./scripts/run-qemu.sh -r /
>> +#
>> +# Run the same with SDL:
>> +#
>> +# $ ./scripts/run-qemu.sh -r / --sdl
>> +#
>> +# Or with a PPC build:
>> +#
>> +# $ ARCH=ppc ./scripts/run-qemu.sh -r /
>> +#
>> +# PPC with a mac99 model by passing options to QEMU:
>> +#
>> +# $ ARCH=ppc ./scripts/run-qemu.sh -r / -- -M mac99
>> +#
>> +
>> +USE_SDL=
>> +USE_VNC=
>> +USE_GDB=1
>> +KERNEL_BIN=arch/x86/boot/bzImage
>> +MON_STDIO=
>> +KERNEL_APPEND2=
>> +SERIAL=ttyS0
>> +SERIAL_KCONFIG=SERIAL_8250
>> +BASENAME=$(basename "$0")
>> +
>> +function usage() {
>> + echo "
>> +$BASENAME allows you to execute a virtual machine with the Linux kernel
>> +that you just built. To only execute a simple VM, you can just run it
>> +on your root fs with \"-r / -a init=/bin/bash\"
>> +
>> + -a, --append parameters
>> + Append the given parameters to the kernel command line.
>> +
>> + -d, --disk image
>> + Add the image file as disk into the VM.
>> +
>> + -D, --no-gdb
>> + Don't run an xterm with gdb attached to the guest.
>> +
>> + -r, --root directory
>> + Use the specified directory as root directory inside the guest.
>> +
>> + -s, --sdl
>> + Enable SDL graphical output.
>> +
>> + -S, --smp cpus
>> + Set number of virtual CPUs.
>> +
>> + -v, --vnc
>> + Enable VNC graphical output.
>> +
>> +Examples:
>> +
>> + Run the host root fs inside a VM:
>> + $ ./scripts/run-qemu.sh -r /
>> +
>> + Run the same with SDL:
>> + $ ./scripts/run-qemu.sh -r / --sdl
>> +
>> + Or with a PPC build:
>> + $ ARCH=ppc ./scripts/run-qemu.sh -r /
>> +
>> + PPC with a mac99 model by passing options to QEMU:
>> + $ ARCH=ppc ./scripts/run-qemu.sh -r / -- -M mac99
>> +"
>> +}
>> +
>> +function require_config() {
>> + if [ "$(grep CONFIG_$1=y .config)" ]; then
>> + return
>> + fi
>> +
>> + echo "You need to enable CONFIG_$1 for run-qemu to work properly"
>> + exit 1
>> +}
>> +
>> +function has_config() {
>> + grep -q "CONFIG_$1=y" .config
>> +}
>> +
>> +function drive_if() {
>> + if has_config VIRTIO_BLK; then
>> + echo virtio
>> + elif has_config ATA_PIIX; then
>> + echo ide
>
> + require_config "BLK_DEV_SD"
>
> Maybe there should also be a warning if no standard FS (ext[34], btrfs,
> xfs etc.) is build into the kernel.
>
> Another thing, but that's just a recommendation for initrd-free mode:
> DEVTMPFS_MOUNT
>
>> + else
>> + echo "\
>> +Your kernel must have either VIRTIO_BLK or ATA_PIIX
>> +enabled for block device assignment" >&2
>> + exit 1
>> + fi
>> +}
>> +
>> +GETOPT=`getopt -o a:d:Dhr:sS:v --long append,disk:,no-gdb,help,root:,sdl,smp:,vnc \
>> + -n "$(basename \"$0\")" -- "$@"`
>> +
>> +if [ $? != 0 ]; then
>> + echo "Terminating..." >&2
>> + exit 1
>> +fi
>> +
>> +eval set -- "$GETOPT"
>> +
>> +while true; do
>> + case "$1" in
>> + -a|--append)
>> + KERNEL_APPEND2="$KERNEL_APPEND2 $KERNEL_APPEND2"
>
> That should be
>
> KERNEL_APPEND2="$KERNEL_APPEND2 $2"
>
>> + shift
>> + ;;
>> + -d|--disk)
>> + QEMU_OPTIONS="$QEMU_OPTIONS -drive \
>> + file=$2,if=$(drive_if),cache=unsafe"
>
> if [ $? != 0 ]; then
> exit $?
> fi

Not sure I understand this one. There's no program executing here...

Alex