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diff --git a/history/port_to_l4.mdwn b/history/port_to_l4.mdwn index b58c0d91..3f951a64 100644 --- a/history/port_to_l4.mdwn +++ b/history/port_to_l4.mdwn @@ -1,108 +1,13 @@ -[[!meta copyright="Copyright © 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, -2009, 2010 Free Software Foundation, Inc."]] +[[!meta copyright="Copyright © 2011 Free Software Foundation, Inc."]] [[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable id="license" text="Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license -is included in the section entitled -[[GNU Free Documentation License|/fdl]]."]]"""]] +is included in the section entitled [[GNU Free Documentation +License|/fdl]]."]]"""]] -[[!meta title="Porting the Hurd to L4: Hurd/L4"]] +[[!tag stable_URL]] -There was an effort to port the Hurd from [[microkernel/Mach]] to the -[[L4_microkernel_family|microkernel/L4]]. - -The idea of using L4 as a [[microkernel]] for a [[Hurd_system|hurd]] was -initially voiced in the [[Hurd_community|community]] by Okuji Yoshinori, who, -for discussing this purpose, created the [[mailing lists/l4-hurd]] mailing list -in November 2000. - -The project itself then was mostly lead by Marcus Brinkmann and Neal Walfield. -Even though there was progress -- see, for example, the -[[QEMU image for L4|hurd/running/qemu/image for l4]] -- this port never reached a -releasable state. Eventually, a straight-forward port of the original Hurd's -design wasn't deemed feasible anymore by the developers, partly due to them not -cosidering L4 suitable for implementing a general-purpose operating system on -top of it, and because of deficiencies in the original Hurd's design, which -they discovered along their way. Read the [[hurd/critique]] and a -[[hurd/ng/position paper]]. - -By now, the development of Hurd/L4 has stopped. However, Neal Walfield moved -on to working on a newly designed kernel called [[microkernel/viengoos]]. - -Over the years, a lot of discussion have been held on the -[[mailing lists/l4-hurd]] mailing list, which today is still the right place -for [[next-generation Hurd|hurd/ng]] discussions. - -Development of Hurd/L4 was done in the `hurd-l4` module of the Hurd CVS -repository. The `doc` directory contains a design document that is worth -reading for anyone who wishes to learn more about Hurd/L4. - - -One goal of porting the Hurd to L4 was to make the Hurd independend of Mach -interfaces, to make it somewhat microkernel-agnostic. - -Mach wasn't maintained by its original authors anymore, so switching to a -well-maintained current [[microkernel]] was expected to yield a more solid -foundation for a Hurd system than the decaying Mach design and implementation -was able to. - -L4 being a second-generation [[microkernel]] was deemed to provide for a faster -system kernel implementation, especially in the time-critical [[IPC]] paths. -Also, as L4 was already implemented for a bunch of different architectures -(IA32, Alpha, MIPS; SMP), and the Hurd itself being rather archtecture-unaware, -it was expected to be able to easily support more platforms than with the -existing system. - -A design upon the lean L4 kernel would finally have moved devices drivers out -of the kernel's [[TCB]]. - - -One idea was to first introduce a Mach-on-L4 emulation layer, to easily get a -usable (though slow) Hurd-using-Mach-interfaces-on-L4 system, and then -gradually move the Hurd servers to use L4 intefaces rather than Mach ones. - - -Neal Walfield started the original Hurd/L4 port while at Karlsruhe in 2002. He -explains: - -> My intention was to adapt the Hurd to exploit L4's concepts and intended -> [[design_pattern]]s; it was not to simply provide a Mach -> [[compatibility_layer]] on top of L4. When I left Karlsruhe, I no longer had -> access to [[microkernel/l4/Pistachio]] as I was unwilling to sign an NDA. -> Although the specification was available, the Karlsruhe group only [released -> their code in May -> 2003](https://lists.ira.uni-karlsruhe.de/pipermail/l4ka/2003-May/000345.html). -> Around this time, Marcus began hacking on Pistachio. He created a relatively -> complete run-time. I didn't really become involved again until the second -> half of 2004, after I complete by Bachelors degree. - -> Before Marcus and I considered [[microkernel/Coyotos]], we had already -> rejected some parts of the Hurd's design. The -> [[open issues/resource management problems]] were -> what prompted me to look at L4. Also, some of the problems with -> [[hurd/translator]]s were already well-known to us. (For a more detailed -> description of the problems we have identified, see our [[hurd/critique]] in the -> 2007 July's SIGOPS OSR. We have also written a forward-looking -> [[hurd/ng/position paper]].) - -> We visited Jonathan Shapiro at Hopkins in January 2006. This resulted in a -> number of discussions, some quite influential, and not always in a way which -> aligned our position with that of Jonathan's. This was particularly true of -> a number of security issues. - -A lange number of discussion threads can be found in the archives of the -[[mailing lists/l4-hurd]] mailing list. - -> Hurd-NG, as we originally called it, was an attempt to articulate the system -> that we had come to envision in terms of interfaces and description of the -> system's structure. The new name was selected, if I recall correctly, as it -> clearly wasn't the Hurd nor the Hurd based on L4. - - -The source code is still available in [CVS module -`hurd-l4`](http://savannah.gnu.org/cgi-bin/viewcvs/hurd/hurd-l4/) (note that -this repository has in the beginning also been used for Neal's -[[microkernel/Viengoos]]). +[[!meta redir=port_to_another_microkernel]] |