User Mode Linux HOWTO

User Mode Linux Core Team

1. Introduction

• 1.1 How is User Mode Linux Different?
• 1.2 Why Would I Want User Mode Linux?

2. Compiling the kernel and modules

• 2.1 Compiling the kernel
• 2.2 Compiling and installing kernel modules

3. Running the kernel and logging in

• 3.1 Running UML
• 3.2 Logging in
• 3.3 Examples

4. Setting up the network

• 4.1 General setup
• 4.2 Userspace daemons
• 4.3 Specifying ethernet addresses
• 4.4 UML interface setup
• 4.5 Multicast
• 4.6 TUN/TAP
• 4.7 Ethertap
• 4.8 The switch daemon
• 4.9 Slip
• 4.10 Setting up the host yourself

5. Sharing Filesystems between Virtual Machines

• 5.1 A warning
• 5.2 Using layered block devices
• 5.3 Note!
• 5.4 Another warning
• 5.5 uml_moo : Merging a COW file with its backing file

6. Creating filesystems

• 6.1 Create the filesystem file
• 6.2 Assign the file to a UML device
• 6.3 Creating and mounting the filesystem

7. Host file access

• 7.1 Using hostfs
• 7.2 hostfs as the root filesystem
• 7.3 Building hostfs

8. The Management Console

• 8.1 version
• 8.2 halt and reboot
• 8.3 config
• 8.4 remove

9. Kernel debugging

• 9.1 Starting the kernel under gdb
• 9.2 Attaching gdb to the kernel
• 9.3 Debugging modules
• 9.4 Using alternate debuggers

10. Kernel debugging examples

• 10.1 The case of the hung fsck
• 10.2 Episode 2: The case of the hung fsck

11. What to do when UML doesn't work

• 11.1 Child nnnnn exited with signal 11
• 11.2 Segfault in padzero
• 11.3 Out of pty's in getmaster
• 11.4 Can't set up the umn device : "Failed to set slip line discipline"
• 11.5 Stack overflowed onto current_task page
• 11.6 Strange compilation errors when you build from source
• 11.7 UML hangs on boot after mounting devfs
• 11.8 A variety of panics and hangs with /tmp on a reiserfs filesystem
• 11.9 The compile fails with errors about conflicting types for 'open', 'dup', and 'waitpid'
• 11.10 UML doesn't work when /tmp is an NFS filesystem
• 11.11 UML hangs on boot when compiled with gprof support
• 11.12 syslogd dies with a SIGTERM on startup
• 11.13 TUN/TAP networking doesn't work on a 2.4 host
• 11.14 You can network to the host but not to other machines on the net
• 11.15 I have no root and I want to scream
• 11.16 UML build conflict between ptrace.h and ucontext.h
• 11.17 Any other panic, hang, or strange behavior

12. Diagnosing Problems

• 12.1 Case 1 : Normal kernel panics
• 12.2 Case 2 : Tracing thread panics
• 12.3 Case 3 : Tracing thread panics caused by other threads
• 12.4 Case 4 : Hangs

13. Thanks

• 13.1 Code and Documentation
• 13.2 Flushing out bugs
• 13.3 Buglets and clean-ups
• 13.4 Case Studies
• 13.5 Other contributions