Enable the kernel to run as a userland process on top of itself

[axeld]

As a testbed for kernel development, profiling, etc. a virtual kernel running on top of the actual kernel would be beneficial. Also having it run on top of ie. Linux or BeOS would be nice, if possible, especially as long Haiku is not self hosting.

Jonas Sundström was kind enough to collect some more informations, mostly from the DragonFly project:

"Reduces the engineering cycle time for testing new kernel code

from 5 minutes to 5 seconds." -- Matthew Dillon

DragonFlyBSD:
Reasons for wanting to have a working virtual kernel
​http://leaf.dragonflybsd.org/mailarchive/kernel/2007-01/msg00082.html

A few questions and answers
​http://leaf.dragonflybsd.org/mailarchive/users/2007-01/msg00237.html

Performance ans system resources
​http://leaf.dragonflybsd.org/mailarchive/kernel/2007-01/msg00107.html

Use of memory
​http://leaf.dragonflybsd.org/mailarchive/kernel/2007-01/msg00157.html
​http://leaf.dragonflybsd.org/mailarchive/kernel/2007-01/msg00039.html

Short-term goals
​http://leaf.dragonflybsd.org/mailarchive/kernel/2007-01/msg00010.html

A few tickets
​http://leaf.dragonflybsd.org/mailarchive/kernel/2007-01/msg00002.html

Function conflicts between kernel and libc
​http://leaf.dragonflybsd.org/mailarchive/kernel/2006-12/msg00018.html
​http://leaf.dragonflybsd.org/mailarchive/kernel/2006-12/msg00030.html
​http://leaf.dragonflybsd.org/mailarchive/kernel/2006-12/msg00039.html

Man page
​http://leaf.dragonflybsd.org/cgi/web-man?command=vkernel&section=ANY

Production uses for virtual kernels
​http://leaf.dragonflybsd.org/mailarchive/kernel/2007-01/msg00054.html

"Checkpointing" vkernels
​http://leaf.dragonflybsd.org/mailarchive/kernel/2007-02/msg00079.html

Linux:
​http://user-mode-linux.sourceforge.net/kernel.html
​http://user-mode-linux.sourceforge.net/UserModeLinux-HOWTO.html
​http://en.wikipedia.org/wiki/User-mode_Linux

[jonas.kirilla]

Some more on DragonFlyBSD's implementation, FWIW.

mmap(.. MAP_VPAGETABLE ..) - with code snippet
​http://leaf.dragonflybsd.org/mailarchive/kernel/2006-09/msg00043.html

Commits - Adjustments to low level madvise/mcontrol/mmap support code to accomodate vmspace_*() calls
​http://leaf.dragonflybsd.org/mailarchive/commits/2006-09/msg00139.html

What the real kernel does and what the virtual kernel does
​http://leaf.dragonflybsd.org/mailarchive/kernel/2006-09/msg00013.html

Devices that might be meaningful in a virtual kernel
​http://leaf.dragonflybsd.org/mailarchive/kernel/2006-09/msg00038.html