Ho Ho Ho! Santa came and went early this morning, and it seems he left a special little something under the tree for filesystem hackers: a Tux3 Kernel Playset. (Some assembly required.) Tux3 is running in kernel now, a little shaky but more or less as a Posix filesystem. Fsx-linux[1] runs somewhat unreliably, with occasional asserts because of missing SMP locking: file btrees are properly locked, but the inode table and allocation bitmap have no protection whatsover. It is actually kind of surprising that these runs complete at all at this point, and it is nice to see the failures showing up as asserts instead of oopses and lockups. This is not yet a request for review because there are still a few things we feel must be in to call it presentable. Mainly, completing SMP lock coverage and atomic commit, and cleaning up some block leaks. Heavy development continues. Most of it continues to be done in userspace. In fact, 80 percent of the Tux3 kernel code also runs in user space. The remainder is VFS API glue and wrappers to abstract away a few differences between kernel and userspace, like the fact that there is only one kind of inode in userspace and many in kernel. I would have to say, this is probably the most unique aspect of Tux3 right now. We are able to implement major changes in user space and expect them to work in kernel on the first try. Here is a quick HowTo, to get your Tux3 Playset up and running: # Get a kernel tree: wget http://kernel.org/pub/linux/kernel/v2.6/linux-2.6.26.5.tar.bz2 tar -xjf linux-2.6.26.5.tar.bz2 cd linux-2.6.26.5 # Get the Christmas tux3 patch and patch the kernel: wget http://tux3.org/patches/tux3-2.6.26.5-3 patch <tux3-2.6.26.5-3 -p1 # Build linux with tux3: make defconfig make CONFIG_TUX3=y sudo make install # Get the Christmas tux3 userspace snapshot: wget http://tux3.org/downloads/snapshots/tux3-20081225.tar.gz tar -xzf tux3-20081225.tar.gz cd tux3/user make # make a tux3 filesystem sudo ./tux3 mkfs /dev/<testpartition> Boot and mount! cat /proc/filesystems | grep tux3 && mount /dev/<testpartition> /mnt Also see my earlier guide to developing Tux3 under user mode linux: http://lwn.net/Articles/308950/ Caveats: Developmental filesystem! Use if you want to poke and play, do not even think about storing valuable data on it. Tux3 obeys sync at this point, but not fsync. No atomic commit means that shutting off the power without sync _will_ corrupt the filesystem image. More caveats: We do not handle source dependencies awfully well in the userspace makefile. You need libpopt-dev and a few other things to build it. Early code adopters know the drill: you see roughly what development packages are missing from the build errors. Design documentation is copious but distributed throughout our mailing list archives. We hope to do something about that soon. In-source documentation is still very sparse, although some work has started on that, for example, commenting fields in the main data structures. The kernel code runs with _loads_ of printk tracing output, which will be disabled with a runtime tracing flag pretty soon, but right now is the primary way we figure out what is going on inside. Yet more caveats: Although the coding style is largely "lindent", there are a few departures that may hurt some people's eyes, for example inline declarations. Please bear with us. We do it that way because it makes the code easier to refactor, still an important consideration at this point. There are some C++ style comments, please do not be outraged. This is one of our ways of saying FIXME: whatever transgressions those comments document should all be gone by the time this code is kernel-ready. Even more caveats: We build on 2.6.26.5 right now, which is getting ancient. A sync-up with current Git trees is coming, and we will set up a proper Git tree for people to pull from. Finally: Developers interested in taking a poke are more than welcome. There are lots of little bits still needing doing, and some of the work is really interesting. We are doing something new and fun here, and we would like you to be a part of it. http://tux3.org irc.oftc.net #tux3 Regards, Daniel [1] fsx-linux filesystem exerciser: http://www.codemonkey.org.uk/projects/fsx/ -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
