6 ms·

Xv6, a simple Unix-like teaching operating system

63 points by rspivak 11y ago

jlappi 11y ago
This is an excellent little project to play with if you want to learn more about the functions of the kernel. The accompanying book is a great resource and provides relatively simple projects.
shavenwarthog2 11y ago
This is an excellent tool for learning Unix-type systems. At < 10K lines, it's much smaller than Linux v1, but has most of the parts of a more mature kernel. The source code is clear, and well documented in its own booklet. Highly recommended.
luckydude 11y ago
Huh, I think HN killed their git server, I started the clone and it's just sitting there doing nothing after 100K. Eventually dies with: pdos.csail.mit.edu[0: 128.52.129.126]: errno=Connection timed out Just FYI for anyone else trying. I looked and this seems to be a mirror that contains the branch they mention: https://github.com/sometimesfood/xv6 https://github.com/sometimesfood/xv6 and you might need this (I did): sudo apt-get install libc6-dev-i386 but the stock qemu didn't seem to work, their server is kaput, and no mirror on github :(
- jey 11y ago
  I think this is the official mirror: https://github.com/mit-pdos/xv6-public https://github.com/mit-pdos/xv6-public
- luckydude 11y ago
  I contacted them and they said use this: git://github.com/mit-pdos/xv6-public.git And OP should correct the original link to: https://pdos.csail.mit.edu/6.828/2014/xv6.html https://pdos.csail.mit.edu/6.828/2014/xv6.html
  - luckydude 11y ago
    Has anyone gotten their qemu to compile? I patched around this problem (I have gcc 4.something): ansel:~/xv6/qemu ./configure --disable-kvm ERROR: glib-2.12 required to compile QEMU and then hit this one: ansel:~/xv6/qemu ./configure --disable-kvm ERROR: DTC not present. Your options: (1) Preferred: Install the DTC devel package (2) Fetch the DTC submodule, using: git submodule update --init dtc got the submodule, did a make: Makefile:116: * target pattern contains no `%'. Stop. I'm on Ubuntu 14.04.3 and up to date.
    - achernya 11y ago
      Which qemu are you cloning? When we taught 6.828 over IAP term we ported the patches to qemu 1.7.0 and put them up at https://github.com/geofft/qemu https://github.com/geofft/qemu. I see the repo has a 2.3.0 and 2.4.0 branch now too. I last built 1.7.0 on Debian 6 (squeeze); newer Debian and Ubuntu should work fine. (Make sure you have libsdl1.2-dev installed)
      - luckydude 11y ago
        I got it to work but I have no idea how. I tried all the branches and the official sources, they all failed the same way. I deleted and recloned the 1.7.0 branch and that worked. Shrug. Thanks for your help.
- jbangert 11y ago
  MIT PDOS also cleaned up its infrastructure a while back. Jon (a student there who does cool scalability research) replaced the old ailing server that hosted a lot of things and that wasn't really maintained by anybody with a set of modern vms, not sure if he also moved over the public git server...
gravypod 11y ago
Are there any projects like that that show people how to write a bootloader? I have been wanting to write something like Xv6 except I want to write everything that will be running except BIOS code. I have yet to find something on bootloader code.
- Samathy 11y ago
  The BrokenThorn OS Dev tutorials have a great section for bootloader development. [1] You can find a whole bunch more stuff on the OS Dev Wiki too. [2] [1] http://www.brokenthorn.com/Resources/OSDevIndex.html http://www.brokenthorn.com/Resources/OSDevIndex.html [2] wiki.osdev.org
sfishman 11y ago
Harvard also has something similar for their OS course (now used outside of Harvard as well) called OS/161. http://os161.eecs.harvard.edu http://os161.eecs.harvard.edu
- mveety 11y ago
  I really like the System/161 simulator that they use with it. They made some good choices sticking to the simple R3000 MMU model.
IshKebab 11y ago
Seems a bit sad to me that we're still teaching a 40 year old OS. Hasn't computing advanced since then? Where's the Plan9-like teaching OS?

63 points by rspivak 11y ago

This is an excellent little project to play with if you want to learn more about the functions of the kernel. The accompanying book is a great resource and provides relatively simple projects.

shavenwarthog2 11y ago

This is an excellent tool for learning Unix-type systems. At < 10K lines, it's much smaller than Linux v1, but has most of the parts of a more mature kernel. The source code is clear, and well documented in its own booklet. Highly recommended.

luckydude 11y ago

Huh, I think HN killed their git server, I started the clone and it's just sitting there doing nothing after 100K. Eventually dies with: pdos.csail.mit.edu[0: 128.52.129.126]: errno=Connection timed out Just FYI for anyone else trying. I looked and this seems to be a mirror that contains the branch they mention: https://github.com/sometimesfood/xv6 https://github.com/sometimesfood/xv6 and you might need this (I did): sudo apt-get install libc6-dev-i386 but the stock qemu didn't seem to work, their server is kaput, and no mirror on github :(

jey 11y ago
I think this is the official mirror: https://github.com/mit-pdos/xv6-public https://github.com/mit-pdos/xv6-public
luckydude 11y ago
I contacted them and they said use this: git://github.com/mit-pdos/xv6-public.git And OP should correct the original link to: https://pdos.csail.mit.edu/6.828/2014/xv6.html https://pdos.csail.mit.edu/6.828/2014/xv6.html
- luckydude 11y ago
  Has anyone gotten their qemu to compile? I patched around this problem (I have gcc 4.something): ansel:~/xv6/qemu ./configure --disable-kvm ERROR: glib-2.12 required to compile QEMU and then hit this one: ansel:~/xv6/qemu ./configure --disable-kvm ERROR: DTC not present. Your options: (1) Preferred: Install the DTC devel package (2) Fetch the DTC submodule, using: git submodule update --init dtc got the submodule, did a make: Makefile:116: * target pattern contains no `%'. Stop. I'm on Ubuntu 14.04.3 and up to date.
  - achernya 11y ago
    Which qemu are you cloning? When we taught 6.828 over IAP term we ported the patches to qemu 1.7.0 and put them up at https://github.com/geofft/qemu https://github.com/geofft/qemu. I see the repo has a 2.3.0 and 2.4.0 branch now too. I last built 1.7.0 on Debian 6 (squeeze); newer Debian and Ubuntu should work fine. (Make sure you have libsdl1.2-dev installed)
    - luckydude 11y ago
      I got it to work but I have no idea how. I tried all the branches and the official sources, they all failed the same way. I deleted and recloned the 1.7.0 branch and that worked. Shrug. Thanks for your help.
jbangert 11y ago
MIT PDOS also cleaned up its infrastructure a while back. Jon (a student there who does cool scalability research) replaced the old ailing server that hosted a lot of things and that wasn't really maintained by anybody with a set of modern vms, not sure if he also moved over the public git server...

gravypod 11y ago

Are there any projects like that that show people how to write a bootloader? I have been wanting to write something like Xv6 except I want to write everything that will be running except BIOS code. I have yet to find something on bootloader code.

Samathy 11y ago
The BrokenThorn OS Dev tutorials have a great section for bootloader development. [1] You can find a whole bunch more stuff on the OS Dev Wiki too. [2] [1] http://www.brokenthorn.com/Resources/OSDevIndex.html http://www.brokenthorn.com/Resources/OSDevIndex.html [2] wiki.osdev.org

sfishman 11y ago

Harvard also has something similar for their OS course (now used outside of Harvard as well) called OS/161. http://os161.eecs.harvard.edu http://os161.eecs.harvard.edu

mveety 11y ago
I really like the System/161 simulator that they use with it. They made some good choices sticking to the simple R3000 MMU model.

IshKebab 11y ago

Seems a bit sad to me that we're still teaching a 40 year old OS. Hasn't computing advanced since then? Where's the Plan9-like teaching OS?