From time to time, I test from upstream qemu to try out some specific area that I’m interested in (lately, block layer operations). Here’s how I try to build qemu from upstream git source, for a specific target — x86_64.
Install development tools (I’m using a Fedora 18 machine here). And a couple of other development libraries
$ yum groupinstall "Development Tools" $ yum install glib2-devel zlibrary zlib-devel -y
Clone the qemu upstream source tree
$ git clone git://git.qemu.org/qemu.git $ cd qemu
Run the qemu configure script for x86_64 architecture, and run make
$ ./configure --target-list=x86_64-softmmu \ --disable-werror --enable-debug $ make -j5
Note: When the qemu configure script is invoked, it’ll throw an error asking you to either install the pixman package or fetch its git submodule.
I fetched pixman submodule
$ git submodule update --init pixman
If you have an OS disk image handy, you can invoke the newly built qemu binary to boot a guest on the stdio, assuming there’s a serial console enabled — having console=tty0 console=ttyS0,115200 inside your guest’s kernel command line in /etc/grub2.conf
$ ./x86_64-softmmu/qemu-system-x86_64 --enable-kvm \ -smp 2 -m 1024 /export/images/fedora18.qcow2 \ -nographic
Note: With the above invocation, --enable-kvm parameter will make use of existing kvm kernel module from the system.
Kashyap Chamarthy 
Instead of manually installing qemu’s build dependencies (zlib-devel, pixman-devel and many more) you can also ‘yum-builddep’ them. As long as the requirements didn’t change compared to the fedora package you’re ready to go then.
Right, I usually do that — yum-builddep — while building libguestfs. But for qemu, it asked me to install 306 M of installed pkgs, so I manually built it. However, thanks for the reminder.
Also a fun libguestfs command:
This page lists some common targets.
Ah, it’s in the ‘extra-tests’ section in Makefile.am. Thanks Rich, very useful.
While I have your attention here, Rich, can I ask you to add a ‘Search’ bar on your blog? It has a goldmine of useful information. The other day, I recall Eric Blake trying to search for a specific article.
Search bar: added.
My ./configure line is a bit longer, but I think it makes more sense for x86 KVM virt guest:
./configure –target-list=x86_64-softmmu –audio-card-list=hda –disable-nptl –disable-guest-base –enable-spice –disable-werror –disable-usb-redir –disable-smartcard-nss –disable-xen –disable-curses –disable-docs –disable-guest-agent –disable-seccomp –enable-vhost-net –disable-linux-user –disable-bsd-user –disable-slirp –disable-system –disable-bluez –audio-card-list=ac97,hda –disable-virtfs –enable-linux-aio $1
Nice, you get a fine grained qemu binary. And, like you said, useful for x86_64 KVM guests – that’s what I need.
Thank you for this info, Yaniv.
Any idea what is the difference between QEMU configure targets x86_64-linux-user and x86_64-softmmu? The former creates qemu-x86_64 binary and the latter qemu-system-x86_64.