Talk:Jochen Liedtke

Article expanded
I've added some detail to this article, but all I had to go on was the "In Memorium" page and Prof. Dr. Liedtke's publications. If I got anything wrong, please fix it. Thanks, CWC (talk) 07:41, 6 September 2006 (UTC)


 * I've added a fair bit more detail (incl references) and a picture obtained from his widow. I've consequently removed the stub tag. Some of the information was sourced from the German version of the obituary at KIT, a bit is personal communication.heiser (talk) 06:26, 19 August 2012 (UTC)

Useful links
(Neither of these links have his PhD thesis or the technical reports he contributed.) Cheers, CWC (talk) 07:41, 6 September 2006 (UTC)
 * Prof. Dr. Liedtke's DBLP page is http://www.sigmod.org/dblp/db/indices/a-tree/l/Liedtke:Jochen.html.
 * His ACM publications can be found here, but the PDFs at http://i30www.ira.uka.de/aboutus/people/personal/liedtke/ are often smaller and easier to read.

Pager?

 * He also proposed using a hierarchy of external pagers, an important feature of modern microkernels.

What is a pager, especially what is an external pager? Thanks, --Abdull (talk) 21:15, 4 August 2010 (UTC)


 * Good question. Thanks for spotting that!
 * As I understand it (I'm no expert), a "pager" in a microkernel system is basically a page fault handler. For example, a pager might map virtual memory to a file in a file system on a hard disk. The whole idea of a microkernel is to put things like that outside the microkernel, so you want to be able to have one address space use a pager whose code and data live in another address space — an external pager. In fact, an external pager will normally handle page faults for multiple address spaces, and each address space would typically have different external pagers for different regions of virtual memory.
 * Furthermore, it turns out to be very useful to "stack" pagers: write a pager which uses another pager for storage instead of (say) a hard disk. For example, you could have a special pager for shared library code "stacked" over the pager for the file containing that code.
 * In his excellent 1995 SOSP paper, Dr Liedtke showed that you only need 3 microkernel primitives to allow such a hierarchy. (The primitives are simple; using them well is a lot more complex!)
 * I've edited the article to add "(page fault handler)" after the word "pager". I'm not sure whether a more detailed explanation would be appropriate. What do you think, Abdull? Does anyone else want to comment? Cheers, CWC 16:27, 11 August 2010 (UTC)

L3 page references were not synchronized
At the time of writing this, there existed a distinct (stub quality, I admit) L3 microkernel page. The Jochen Liedtke page L3 link went to a section about predecessors in the L4 page, L4 microkernel family. I don't know if this is intentional. Feel free to (merge the L3 and L4 pages, change the "Known For" link in the infobox from L3 microkernel and) revert this (08:51, 31 March 2012) change. This is little more of a venture than what I'm up to in my drive-by saturday amusement edits... Rootmoose (talk) 09:14, 31 March 2012 (UTC)
 * I support merging L3 into L4, L3 is only noteworthy as L4's predecessor. heiser (talk) 06:26, 19 August 2012 (UTC)


 * For the record, this merge has been done (in July 2017). CWC 12:37, 27 November 2017 (UTC)

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