Linux Gazette MailBag Issue #18

#### "Linux Gazette...making Linux just a little more fun!"

## The Mailbag! Write the Gazette at gazette@ssc.com | ### Contents: Help Wanted -- Article Ideas General Mail

### Help Wanted -- Article Ideas

Date: Wed May 28 11:16:14 1997
Subject: Help wanted: 2.1.40 will not boot
From: Duncan Simpson, D.P.Simpson@ecs.soton.ac.uk

2.1.40 dies after displaying the message Checking whether the WP bit is honored even in supervisor mode...

A few prints hacked in later reveals that in enters the page fault handler, detects the bootup test and gets to the end of the C (do_fault in traps.c). However it never gets back to continue booting---exactly where it gets lost is obscure.

Anyone have any ideas/fixes?

Duncan

Date: Fri, 16 May 1997 16:17:47 -0400
Subject: CD-ROMs
From: James S Humphrye, humpjs@aur.alcatel.com

I just found the LG today, and I have read most of the back issues... Great job so far! Lots of really useful info in here!

Now to my "problem". I installed Slackware 3.0, which went just fine. I had XFree86 and all the goodies working perfectly (no, really, it all worked just great!) Then I upgraded my machine to a P150, and installed a Trident 9660) PCI video card. Then the X server wasn't happy any more. So...I upgraded the kernel sources to 2.0.29, got all the required upgrades for GCC, etc. I built a new kernel, and it was up and running...sort of.

Despite having compiled in support for both IDE and SCSI CDROMs, I can only get the IDE one to work. I have edited the rc.* scripts, launched kerneld, run depmod -s, and all the other things the docs recommend.

I have rebuilt the kernel to zdisk about 25 times, trying different combinations of built-in and module support, all to no avail. When the system boots, the scsi host adapter is not detected (it is an AHA1521, located on a SB16/SCSI-2 sound card, and it worked fine under 1.2.13 & 1.3.18 kernels) When the aha152x module tries to load, it says it does not recognize scd0 as a block device. If I try to mount the SCSI unit, it says "init_module: device or resource busy". Any advice would be welcome. What I want is to at least be able to use the SCSI CDROM under Linux, or better yet, both it and the IDE CDROM...

There are also a bunch of messages generated by depmod about unresolved symbols that I don't understand, as well as a bunch of lines generated by modprobe that say "cannot locate block-major-XX" (XX is a major number, and the ones I see are for devices not installed or supported by the kernel) The second group of messages may be unimportant, but I don't know..

Thanks in advance, Steve

Date: Mon, 26 May 1997 12:18:40 -0700
Subject: Need Help From Linux Gazette
From: Scott L. Colantonio, scott@burbank.k12.ca.us

Hi... We have Linux boxes located at the remote schools and the district office. All remote school clients (Mac, WinNT, Linux) attempting to access the district office Linux boxes experience a 75 second delay on each transaction. On the other hand, we do not experience any delay when district office clients (Mac, WinNT, Linux) attempt to access the remote school Linux boxes. The delay began when we moved all the remote school clients to a separate network (and different ISP) than the district office servers.

To provide a map, consider this:

remote school <-> city hall city hall <-> Internet Internet <-> district office

We experience a 75 second delay: remote school client -> city hall -> Internet -> District office Linux box

We do not experience any delay: remote school client -> city hall -> Internet

We do not experience any delay: city hall -> Internet -> District office Linux box

We do not experience any delay: District office client -> Internet -> city hall -> remote school Linux box ...

The remote schools use a Linux box at City Hall for the DNS.

In effect, the problem is isolated to the remote school clients connecting to the district office Linux boxes, just one hop away from city hall.

As a result, the mail server is now a 75 second delay away from all educators in our district. Our Cisco reps do not think, after extensive tests, that this is a router configuration problem.

I setup a Microsoft Personal web server at the district office to test if the delay was universal to our route. Unfortunately, there was no delay when remote school clients attempted to access the MS web server.

Is this a known Linux network problem? Why is this a one-way problem?

Any help would be greatly appreciated.

Scott L. Colantonio

Date: Thu, 1 May 1997 16:16:58 -0700
Subject: inetd
From: Toby Reed, toby@eskimo.com

I have a question for the inetd buffs out there...perhaps something like xinetd or a newer version has the capability to do the job, but what I want is this:

    normal behavior:
    connect to inetd
    look in /etc/inetd.conf
    run program

    enhanced behavior:
    connect to inetd
    find out what hostname used to connect to inetd
    look in /etc/inetd.conf.hostname if it exists, if not, use /etc/inetd.conf
    run program listed in /etc/inetd.conf

So if dork1.bob.com has the same IP address as dork2.bob.com, inetd would still be able to distinguish between them. In other words, similar to the VirtualHost directive in Apache that allows you to make virtual hosts that have the same IP address, except that with inetd.

Or, depending on the hostname used to access inetd, inetd could forward the request to another address.

This would be extremely useful in many limited-budget cases where a multitude of IPs are not available. For example, in combination with IP masquerading, would allow a lan host to be accessed transparently both ways on all ports, so long as it was accessed by a hostname, not an IP address. No port masquerading or proxies would be required unless the service needed was very very special. Even non-inetd httpd servers would work with this kind of redirection because the forwarded connection would still be handled by httpd on the machine with the masqueraded machine.

Anyone know if this already exists or want to add to it so I can suggest it to the inetd group?

-Toby

Date: Thu, 8 May 1997 08:05:03 -0700 (PDT)
Subject: S3 Virge Video Board
From: Tim Gray & Family, timgray@lambdanet.com

I have a Linux box using a S3 Virge video board with 4 meg Ram. The problem is that X refuses to start with no other color depth than 8bpp. As X is annoying at 8bpp (Color flashing on every window and several programs complain about no free colors) Is there a way to FORCE X to start in 16 bpp? using the command .... startx -bpp 16 does not work and erasing the 8bpp entry in the XF86Config file causes X to self destruct. Even changing the Depth from 8 to 16 causes errors.. Anyone have experience with this X server?

Date: Fri, 9 May 1997 09:20:05
Subject: Linux and NT
From: Greg McNichol, mcnichol@mcs.net

I am new to LINUX (and NT 4.0 for that matter) and would like any and all information I can get my hands on regarding the dual-boot issue. Any help is appreciated.

--Greg

Date: Wed, 14 May 1997 00:02:04
Subject: Help with CD-ROM
From: Ralph, ralphs@kyrandia.com

I'm relatively new to Linux...not a coder or anything like that...just like messing with new things....anyways I have been running Linux for about a year now and love the H*** out of it. About two weeks ago I was testing some HD's I picked up used with this nifty plug and play bios I got and when I went to restore the system back to normal and now my CD-Rom does not work in Linux...I booted back into 95 and it still worked so I tried forcing the darn thing nothing, nada , zero. I booted with the install disks and still no CD-Rom...its on the 2nd eide set for cable select I tried removing the 2nd hard drive and moving it there still nothing....can anyone give me some more suggestions to try?

Date: Thu, 15 May 1997 12:40:27 -0700
Subject: Programming in C++
From: Chris Walker, crwalker@cc.weber.edu

Hi, I'm Chris Walker. I'm an undergrad computer science major at Weber State University. During my object oriented programming class Linux was brought up. The question was asked "if c++ is so good for programs that are spread over different files or machines, why are Linux and Unix programmed in c not c++?" I was hoping that you may have an answer. Has anyone converted Linux source to c++, would there be any advantages/disadvantages?

Thanks, Chris Walker

Date: Thu, 15 May 1997 11:27:17 -0700 (PDT)
Subject: Programming Serial Ports
From: Celestino Rey Lopez, claude@idecnet.com

First of all congratulations for your good job in the Linux Gazette. I'm interested in programming the serial ports in order to get data from other computers or devices. In other Unixes it is possible, via ioctl, to ask the driver to inform a process with a signal every time a character is ready in the port. For example, in HP-UX, the process receive a SIGIO signal. In Linux SIGIO means input/output error. Do you know where can I get information about this matter? Is there any books talking about that?

Thanks in advance and thanks for providing the Linux community with lot of tricks, ideas and information about this amazing operating system.

Yours, Celestino Rey Lopez.

### General Mail

Date:Fri, 16 May 1997 10:53:18
Subject: Response to VGA-16 Server in LG Issue 17
From: Andrew Vanderstock, Andrew.van.der.Stock@member.sage-au.org.au

I'll look into it, even though VGA_16 has a very short life. Yes, he is correct, there isn't much in the way of testing dual headedness with a herc card and VGA16, as both are getting quite long in the tooth. VGA_16 disappears in a few months to reappear as the argument -bpp 4 on most display adapters. One bug fixer managed to re-enable Herc support in the new source tree a while back, so there may be life there yet.

Also, there was one 2c issue that was a little out of whack in regards to linear addressing. The Cirrus chipsets are not fabulous, but many people have them built into their computers (laptops, HP PC's etc).

All I can suggest is that he try startx -- -bpp 16 and see if that works. If it doesn't have a look at the release notes for his chipset. If all else fails, report any XFree bugs to the bug report cgi on www.xfree86.org

I'll ask the powers that be if I can write an article for you on XFree86 3.3, the next version of the current source tree, as it is due soon. How many words are your articles generally?

Andrew Vanderstock

Date: Sat, 24 May 1997 01:32:29 -0700
Subject: Secure Anonymous FTP setup mini-howto spotted, then lost
From: Alan Bailward, ajb@direct.ca

I saw once on a friend of mines linux box, running Slackware 3.1, in /usr/docs/faq/HOWTO/mini, a mini-howto on how to setup a secure anonymous FTP server. It detailed how to setup all the directories, permissions, and so on, so you could upload, have permissions to write but not delete on your /incoming, etc etc etc. It looked like a great doc, but for the life of me I can't find it! I've looked on the slackware 3.2 cdrom, the 3.1 cdrom, searched all through the net, but to no avail. As I am trying to setup an anonymous ftp site now, this would be invaluable... I'd feel much better reading it than 'chmod 777'ing all over the place :)

If anyone has seen this document, or knows where it is, please let me know. Or even if there is another source of this type of information, I would sure appreciate it sent to me at ajb@direct.ca

Thanks a lot, and keep on Linuxing!

alan

Date: Mon, 26 May 1997 13:21:20 +0800
Subject: Tuning XFree86
From: Soh Kam Yung, kysoh@ctlsg.creaf.com

I've been reading Linux Gazette since day one and it has been great. Keep up the good work.

I've been seeing comments and letters in the Gazette from people who are having trouble with their XFree86. Well, here's a tip for those not satisfied with the way their screen looks (offset to one side, too high/wide, etc.).

While looking through the XFree86 web site for tips on how to tweak my XF86 configuration, I noticed a reference to a program called xvidtune. Not many people may have heard about it, but it is a program used to tune your video modes. Among its features include:

1. the ability to modify your graphics screen 'on-the-fly'. You can move the screen, strech/compress it vertically or horizontally and see the results.
2. it can generate a modeline of the current screen setting. Just copy it into the correct area of your XF86Config file and the next time you start up the XFree86 server, the screen will come up the way you like it.

Just run xvidtune and have fun with it! But be careful: as with XFree86 in general, it does not guarantee that the program will not burn your monitor by generating invalid settings. Fortunately, it has a quick escape (press 'r' to restore your previous screen settings).

Regards, -- Soh Kam Yung

Date: Fri, May 30 1997 12:34:23
Subject: Certification and training courses for Linux
From: Harry Silver, hsilver@pyx.net

I am currently on a mailing list for consultants for Red Hat Linux. One of my suggestions to that list is contained below. I truly hope as part of a broader international initiative, Linux International will pick up the ball on this one so as to ensure that Linux generically will survive. I truly hope that someone from your organization will follow up both with myself and with the Red Hat consulting mailing list as to a more generic Linux support effort in this area. All that would be required is gathering up the manuals from the older Unixware CNE course and 'porting' them to Linux and creating an HTMLized version. This along with online testing could easily generate a reasonable revenue stream for the generic Linux group involved.

Respectfully,

MY SUGGESTION: About two years ago, Novell still had Unixware before sending it over to the care of SCO. At the time Unix was under the stewardship of Novell, a Unixware CNE course was developed. Since, Ray Noorda of Caldera and former CEO of Novell is also an avid supporter of Linux as well as the good folks at Red Hat and other distributions, rather than RE-INVENT the wheel so to speak, wouldn't it make more sense to pattern certification AFTER the Unixware CNE courses by 'porting' the course to Linux GENERICALLY ?

Harley Silver

Date: Fri, 24 May 1996 11:39:25 +0200
Subject: Duplicating a Linux Installed HD
From: Dietmar Kling, kling@tao.de

Hello. I did duplicate my Hard disk before you release this articles for it. A friend of mine new to linux tried to do it, too using your instructions. But we discovered, when he copied my root partition, that he couldn't compile anything on his computer afterwards. A bug in libc.so.5.2.18 prevented his old 8 MB Machine from runnig make or gcc. it always aborted with an error. After updating libc.so5.2.18 and running ldconfig the problem was solved.

We had a SuSe 4.0 installation.

Dietmar

Date: Sat, 10 May 1997 16:09:29 +0200 (MET DST)
Subject: Re: X Color Depth
From: Roland Smith, rsmit06@ibm.net

In response to Michael J. Hammel's 2cent tip in issue #17: I disagree that a 16bit display displays less colors than a 8 bit display.

Both kinds of displays use a colormap. A color value is nothing more than an index into a color map, which is an array of red,green,blue triplets, each 8 bits. The amount of colors that can be shown simultaneously depends on the graphics hardware.

An 8bit display has an eight bit color value, so it can maximally have 256 different color values. The color map links these to 256 different colors which can be displayed simultaneously. Each of these 256 colors can be one of the 2^24 different colors possible with the 3*8 bits in each colormap entry (or color cell, as it is called).

A 16bit display has a sixteen bit color value, which can have 2^16=65536 different values. The colormap links these to 65535 different, simultaneously visible, colors (out of 2^24 possible colors). (actually it's a bit more difficult than this, but thats beyond the point).

So both a 8 and 16 bit display can show 2^24=16.7*10^6 colors. The difference lies in the number of colors they can show *at once*.

Regards, Roland

Date: Fri, May 30 1997 13:24:35
Subject: Using FTP as a shell-command with ftplib

From: Walter Harms, Walter.Harms@Informatik.Uni-Oldenburg.DE ...

Any drawbacks? Of course, for any ftp session you need a user/paswdr. I copy into public area using anonymous/email@ others >will need to surly a password at login, what is not very useful for regular jobs or you have to use some kind of public login but still I think it's easier and >better to use than the r-cmds.

-- walter

Date: Mon, 12 May 1997 17:05:09 -0700
Subject: RE: Using ftp Commands in Shellscript
From: James Boorn, jboorn@optum.com

I recommend you depend on .netrc for ftp usernames and passwords for automated ftp.

James Boorn

Date: Thu, 29 May 1997 09:09:35 -0500
Subject: X limitation to 8 Bit Color (Response to Gary Masters)
From: Omegaman, omegam@COMMUNIQUE.NET

I read your question in Linux Gazette regarding an X limitation to 8 bit color when the system has more that 14 megs of RAM. Where did you find that information? I ask because my system has 24 megs of RAM, and I run 16 bit color all the time. One difference between our systems is that I am using a Diamond Stealth 64 video card.

Gary,

Just caught this letter in Linux Gazette. This limitation is specific to Cirrus Logic cards, particularly those on the ISA bus and some on VLB (ie. old systems -- like mine. Since you're using a Diamond Stealth 64, you don't have this limitation.

Full details are in the readme.cirrus file contained in the XFree86 Documentation. Some cirrus owners may be able to overcome this limitation. See http://xfree86.org

Date: Fri, May 30 1997 8:31:25
Subject: Response to Gary Masters
From: Ivan Griffin, Ivan Griffin@ul.ie

From: Gary Masters gmasters@devcg.denver.co.us

I read your question in Linux Gazette regarding an X limitation to 8 bit color when the system has more than 14 megs of RAM. Where did you find that information? I ask because my system has 24 megs of RAM, and I run 16 bit color all the time. One difference between our systems is that I am using a Diamond Stealth 64 video card.

XFree86 needs to be able to map video memory in at the end of physical memory linearly. However, ISA machines cannot support greater than 16MB in this fashion - so if you have 16 or greater MB or RAM, you cannot run XFree86 in higher than 8 bit color.

Ivan

Published in Linux Gazette Issue 18, June 1997

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