[oclug] Thems fightin words..

[Andrew J. Hutton]

On Wed, 2002-03-13 at 16:31, Greg Franks wrote:

> RMS> The Hurd kernel of FSF's GNU system is more powerful than Linux
> RMS> because it is designed using a microkernel instead of a monolithic
> RMS> architecture, Stallman said.

uKernel's have failed to be impressive in any implementation beyond
those intended for embedded applications.

> Though, if I recall correctly, Hurd was supposed to be based on Mach,
> which might be hard to qualify as a microkernel.  I supposed that the
> proof in the pudding will be actual benchmarks, mai, je digresse....

MACH is in all ways a uKernel. 

The important thing when discussing uKernel vs Monolithic kernel is to
define the two.  In a uKernel IO is generally abstracted into child
processes which do not have a direct view of the underlying hardware. 
In a monolithic kernel, the kernel contains all the drivers and IO
facilities and each driver can see the hardware directly.  

The general effect is with a uKernel the kernel can in theory protect
the hardware from driver problems which in a monolithic kernel would
bring the system down.  It also means that to port the operating system
to a new hardware platform with a uKernel (theory) all you need to do is
port the uKernel itself which is 'usually' small and simple to do
compared to a Monolithic kernel. 

There are worlds of exceptions to the above rules but those are the
basic differences.

-- 
Steamballoon Incorporated, Open Source Design & Development Consulting