How can Minix 3 be so small

Marcus Voelp voelp at
Wed Jun 27 08:47:10 CEST 2007

Hi Gernot,

Gernot Heiser wrote:
> NHW> I recollect from a talk that Jorrit Herder gave about that Minix3 does
> NHW> not support paged memory: it uses segments for enforcing protection,
> NHW> which explains a large part of the difference you observe.
> ... which, among others, means that it cannot set up shared memory
> regions for high-bandwidth cross address-space communication.
> ...
It is possible to setup shared memory with the x86 segments by letting 
them overlap. The x86 segments just add an offset (and check the limit) 
to the segment local address. The result of this translation maps to a 
flat and untranslated (if only segments are used) address space.


Marcus Völp

Technische Universität Dresden
Department of Computer Science
Institute for System Architecture 

Tel: +49 (351) 463 38350
Fax: +49 (351) 463 38284

Email: voelp at

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