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Hurd Traffic #79 For 10 Feb 2001

Editor: Zack Brown

By Paul Emsley  and  Zack Brown

Mach 4 | Hurd Servers | Debian Hurd Home | Debian Hurd FAQ | debian-hurd List Archives | bug-hurd List Archives | Hurd Reference Manual | Hurd Installation Guide | Cross-Compiling GNUMach | Hurd Hardware Compatibility Guide

Table Of Contents

Introduction

Want to help write KC Debian Hurd? See the KC Authorship page the KC Debian Hurd homepage, and the Thread Summary FAQ. Send any questions to the KCDevel mailing list.

Mailing List Stats For This Week

We looked at 49 posts in 192K.

There were 29 different contributors. 8 posted more than once. 7 posted last week too.

The top posters of the week were:

 

1. Hurd Ports
27 Jan 2001 - 31 Jan 2001 (8 posts) Archive Link: "Re: Port to PowerPC"
Summary By Zack Brown
People: Chris SilvaPeter BruinPatrick Strasser

Patrick Strasser wanted to port the Hurd to the Darwin kernel (the core of the Mac OS). At one point Jan Suhr gave a link to the GNU Darwin page. At one point, Chris Silva remarked:

A few problems that you might not be aware of:

  1. Darwin isn't a micro-kernel.
  2. Hurd is a set of servers running on top of a micro-kernel. Currently that micro-kernel is GNU/Mach.

Port GNU/Mach to ppc.

But Peter Bruin added:

That isn't necessary, because Mach 3.0 already works on PPC. I am working to get the Hurd running on it (although I haven't made much progress for a few months because of a hardware problem).

The Hurd could be ported to Darwin (it has most of the Mach interface), but then support needs to be added everywhere for the IOKit and other things changed by Apple.

 

2. Easy Way To Crash The Hurd
28 Jan 2001 - 29 Jan 2001 (4 posts) Archive Link: "Bug#82600: zalloc panic"
Summary By Zack Brown
People: Roland McGrathMarcus Brinkmann

Marcus Brinkmann posted a simple script that would cause a kernel panic in the Hurd. Roland McGrath replied:

you are running a fork bomb. Which is to say, the essence of that program is the same as "while (fork () == 0) ;". Such a program always ends in a pathological resource shortage. Unix has things like per-owner (uid) resource limits on the number of processes that can prevent this (but won't if you're root).

It is certainly the case that the kernel behaves poorly (i.e. panics a lot) in all sorts of extreme resource shortage situations. That is not good, but it would be tedious at best and perhaps really a lot of hard work to make it better in Mach.

There are doubtless nonrobustnesses in the Hurd code as well when it comes to resource shortages. It would a fine thing to find those and fix them. But the kernel dies before those really get exposed.

Though not directly relevant to your report (since it runs as root), real resource limits are also definitely a good thing to have. We really have nothing meaningful in the Hurd; we don't even include resource limits in the protocols for inheritance by exec and such. Many resource controls can only actually be enforced by the kernel, because its interfaces give direct access to kernel resources (vm_allocate, task_create, et al). Some such controls might not be too hard to implement.

 

3. Temporary shutdown
29 Jan 2001 (1 post) Archive Link: "missing "shutdown" command, substitutes?"
Summary By Paul Emsley
People: Marcus Brinkmann

Following up an older thread, Marcus Brinkmann thought that it was cron (or atd) blocking a clean unmounting of the filesystem at shutdown. He attached a script that he hoped would fix the problem for now.

 

4. Implementing pthreads
30 Jan 2001 - 1 Feb 2001 (3 posts) Archive Link: "One more Q: Hurd & pthreads"
Summary By Paul Emsley
People: Ezequiel ReyesNeal WalfieldNiels Möller

Following up last week's threads thread, Ezequiel Reyes asked "Isn't the fact of implementing pthreads using glibc and not the basic thread model provided by the Mach kernel a redundancy?" . Niels Möller and Neal Walfield said no and that pthreads should be implemented on top of the mach thread abstractions.

 

5. New Hurd ISO Image And Installation Disks
31 Jan 2001 - 1 Feb 2001 (7 posts) Archive Link: "tar file, boot floppies"
Summary By Paul Emsley
Topics: Installation
People: Marcus BrinkmannGlenn McGrathPhilip CharlesNeil WalfieldJeff BaileyPaul Emsley

Marcus, suggesting that he was busy, hoped that someone could address the issues needed to release a new tar file. "The various patches needed to get cross-install up to date are in the mailing list archive" .

Marcus also suggested the creation of a Boot Floppies Team. The largest issue for them is the partitioner - but this is being tackled by Neil Walfield working on a Hurd port of GNU Parted. The boot floppies are modular, easy to divide up amongst the workers and much is shareable with Linux. "someone could make a report on this, so that we are all up to date on this and can estimate how big an effort it is. If we can get Debian boot floppies by summer, that would be great."

Glenn McGrath said that the linux boot floppies will use Parted too, but he thought that "configuring the network will be different to linux" . Marcus replied that he had implemented all common network ioclts, and Jeff Bailey is repackaging GNU inetutils, so that "basic network configuration (IP, netmask etc.) is very much the same on the Hurd as for Linux" .

Philip Charles reported his concerns in compiling the CD images suggesting that "a team is necessary" . One of Philip's difficulties was that he could only create the tarball from a GNU/Hurd system (rather than "cross-create" from a GNU/Linux system). "Boot/root disks are easy to create for the Hurd. They use Linux at the moment" .

In reply to Philip's report Marcus went on to say "[The boot/root disks should be Hurd based so that they can] install and use translators in the install program. It also proves that the Hurd really is self-contained. As the root disk is also the rescue disk, having a real Hurd system is not unimportant (in the long run). "

Philip Charles finished the thread saying "The HURD E1 installation CDs are on their way to Budapest today. At the moment I am working with boot-floppies 2.2.17 as I know they work."

(ed. [Paul Emsley] You can get the images from Hungary or planetmirror (Australia).)

 

 

 

 

 

 

Sharon And Joy
 

Kernel Traffic is grateful to be developed on a computer donated by Professor Greg Benson and Professor Allan Cruse in the Department of Computer Science at the University of San Francisco. This is the same department that invented FlashMob Computing. Kernel Traffic is hosted by the generous folks at kernel.org. All pages on this site are copyright their original authors, and distributed under the terms of the GNU General Public License, version 2.0.