linux-kernel - Re: [PATCH] KVM: Add wrapper script around Qemu to test kernels

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Message-ID: <4E54B590.9040408@redhat.com>
Date:	Wed, 24 Aug 2011 11:25:52 +0300
From:	Avi Kivity <avi@...hat.com>
To:	Alexander Graf <agraf@...e.de>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>,
	"linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>,
	"kvm@...r.kernel.org list" <kvm@...r.kernel.org>,
	qemu-devel Developers <qemu-devel@...gnu.org>,
	Pekka Enberg <penberg@...nel.org>
Subject: Re: [PATCH] KVM: Add wrapper script around Qemu to test kernels

On 08/24/2011 01:16 AM, 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!
>
> +
> +function has_config() {
> +	grep "CONFIG_$1=y" .config
> +}

grep -q ?

> +	case "$1" in
> +	-a|--append)
> +		KERNEL_APPEND2="$2"

Might want to append to KERNEL_APPEND2, so you could have multiple -a args.

> +echo "
> +	################# Linux Qemu launcher #################
> +
> +This script executes your currently built Linux kernel using Qemu. If KVM is
> +available, it will also use KVM for fast virtualization of your guest.
> +
> +The intent is to make it very easy to run your kernel. If you need to do more
> +advanced things, such as passing through real devices, please take the command
> +line shown below and modify it to your needs. This tool is for simplicity, not
> +world dominating functionality coverage.

Device assignment could be useful for driver developers, yes.

> +"
> +echo "\
> +Your guest is bound to the current foreground shell. To quit the guest,
> +please use Ctrl-A x"
> +echo "  Executing: $QEMU_BIN $QEMU_OPTIONS -append \"$KERNEL_APPEND\" -smp $SMP"
> +echo
> +
> +exec $QEMU_BIN $QEMU_OPTIONS -append "$KERNEL_APPEND -smp $SMP"

Would be nice to support launching gdb in a separate terminal with 
vmlinux already loaded, and already attached to qemu.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

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