I am the author of a number of software packages and a coauthor of the book Linux Programming Unleashed. This page contains misc. linux information.
Linux is a unix(tm) compatible operating system that is distributed with full source code and is availible for download free of charge or on CD-ROM for about $49.95 for a good solid distribution in a shrink wrapped box with manual. Linux is superior to commercial unix operating systems and totally blows the doors off of proprietary wanna-be operating systems like Windows/95 and Windows/NT. It runs on a various platforms including Intel x86, Sun Sparc, Dec Alpha, and others.
Linux is stable. My primary development machine was up for 101 days before I shut it down for a hardware upgrade. At the time I updated this paragraph on 2/4/98, uptime had this to say:
10:43pm up 89 days, 6:54, 12 users, load average: 0.02, 0.01, 0.00and the web server said
11:00pm up 73 days, 6:02, 2 users, load average: 0.01, 0.01, 0.00and the firwall said:
10:36pm up 86 days, 6:40, 3 users, load average: 0.07, 0.02, 0.00and all were still running. It is becoming routine to have uptimes of order 100 days, normally terminated by some upgrade process or major power outage rather than a malfunction.
Here are some of the experiences I have had with various hardware, particularly hardware that isn't mentioned in the various HOWTO documents. I will add more technical details later about how to actually configure these various devices.
Actually, the cyrix does appear to support the MSR registers but the kernel thinks the cpu is a 486 (because it says it is) and so it doesn't use those features. Cyrix tech support was negligent, however, in not responding to my inquiry regarding support of the MSRs. Installing the 6x86 kernel patches may be sufficient to permit use of these registers.
There are problems running Redhat 5.0 on a cyrix machine which has not had any problem running Redhat 4.0/Linux2.0.27 for many months (uptimes of order 100 days). The problems manifest themselves primarily in two forms: the install program hangs ocassionally and GCC dies due to a signal 11 while compiling large packages (the kernel is a good example).
There is a linux 6x86 FAQ. Note, however, that the problems it mentions are apparently not
the problems with boxes that have run older releases but are unreliable
in redhat 5.0); they appear to be primarily problems with people who
are running second rate machines. The Sig11 FAQ gives a little more upto date info.
Redhat has been working on this problem, but they were unable to reproduce
it on a newer Cyrix processor. In their
this patch which adds a fair amount of support for cyrix chips.
As far as I know, they do not supply a patched
boot disk, which is unfortunate because they install process
is one of the things which is unreliable. Redhat also mentions
the older 6x86 chips in the errata and has an unofficial RPM update for gcc
for this purpose. Newer 6x86MX chips may not suffer these problems.
The changelog for one of the
new gcc RPMs.
mentions on dec 30, 1997: 'changed optimizer flags to -O2 for bootstrap
to fix "broken" Cyrix chips.' This change was made by Make Wangsmo
I have seen mention of a set6x86 program. Here is the debian linux
page for the
set5x86utility; that page has links to the original tar file and a diff
file which looks like it is probably debian specific.
We bought these drives surplus and we have had some trouble with them.
In particular, some or all of the drives cannot read or write plain DDS (as
opposed to DDS-2) 1.3GB tapes. It is also a real pain in the but
if a tape gets stuck in the drive while the tape drive thinks there
isn't one; under those circumstances, it will refuse to eject a tape
and it is necessary to disasemble the drive some and spin a little
four toothed gear like thing inside a bazillion times using a screwdriver,
a quarter turn at a time (sorry, I can't say which way) to get the
tape out. We got one of these drives from a different vendor that
had a sticker attached to it that said use of any but a few brands
of tapes would void the warranty due to excessive head wear.
I have had a pair of Zyxel omni288s modems on a 14000 foot long 2 wire
dry loop leased line for almost 2 years now. They worked pretty well
except for the MAJOR bug which caused the line to go down occassionally and
not come back up. Normally, you could disconnect the phone line and
reconnect it and it would automatically resync like it is supposed to.
The problem
with the line going down often accompanied power cycling the
computer (i.e. was triggered by a handshake line like DTR).
Firmware download. I had to upgrade from the version that was shipped
with the modems to get leased line mode to work at all (much time
wasted) to v1.12 Then, it had problems where it would occassionally
lose the link until the D/V key was hit on both modems (miles apart).
It appears that v1.18 may fix this (the problem only existed after
the modems had been connected for more than 4 hours, which made
reproducing it a tad difficult). To download firmware, you
have to hold down the D/V button on the modem for at least 10 seconds
while cycling power.
I have uploaded the modems on each end of the leased line to
Version 1.19 (as of 10/6/97).
Check for the latest version. at Zyxel's web site.
These are the strings I use to configure the modem for leased line
mode. Note that you have to send these AT commands at the line speed
you want the modem to lock to (i.e. the speed you will use on the
ports for the leased line). I use 38400, even though this will
degrade performance somewhat on compression, because I didn't want any
nasty problems. Once you issue these commands, the modem will be put
into leased line permanently, even if you cycle power; to get the
modem out of leased line mode (and lose these settings) you have to
cycle power on the modem while holding down the D/V button for a
couple seconds, wait a few seconds more, then cycle power again to
reset the EEPROM to factory defaults. If you hold down the D/V button
for too long, you will find yourself in kernel upload mode but if
you don't hold it down long enough it won't reset the EEPROM.
You have to set one modem to originate and the other to answer.
Zyxel technical support has been pretty poor lately. One inquiry
about whether the leased line problem was addressed in newer firmware
releases (it is a major pain to take a leased line down and upload
new firmware on both ends, even more so when one end is connected
to a cisco router) produced no response. When one of
my modems completely lost its marbles, I had to deal with some
clown named Steve Nguyen who sent replies to my messages that
clearly indicated that he had not actually read the messages I sent
him (which were very detailed) so I had to waste my time (and calendar
time as well) playing email tag with him. Then after I Fedex'ed the modem
to zyxel, he let it gather dust for over a month until I bitched.
Their lack of support for non zyxel cellular protocols and 56K
protocols and higher prices are making their products far less
competitive. They also took forever to release rack mount versions
of their products, and when they did, they didn't take T1.
And sportsters are availible with voice
support (perhaps you can get rack mount couriers as well with voice
by now) from USR, which is supported under linux by vgetty, and even
sportster voice clones are availible. And now everyone has downloadable
firmware (originally, zyxel let you download firmware and burn
your own eeproms which was why they were popular in the first place).
General comments on leased line mode. Very few modems support
the &L1 two wire leased line mode these days. Some say they
do in the manual but don't in practice. Some think they do
but are buggy. As far as I know, no manufacturers low end modems
support leased line mode at 28.8Kbs or higher. A good rule of thumb
is that if it costs much less than $200, it doesn't actually support
leased line mode. A leased line capable modem is likely to cost $200-500.
The ModemShop
has a list of modems that ostensibly support leased line mode
including: Hayes Optimas; Motorola Premier, V.3229, V.3400; some MultiTech
models, including rackmounts; USR (3com) Courier V.Everything; and Zyxel Elite
and U-336 series. You do not need a 4 wire leased line capable moddem unless
you are going to use a 4 wire dry loop; this might improve performance a
bit since you do not need the echo cancellation required for 2 way operation
on a 2 wire line which could improve your noise margin.
This works fine with linux. Use "eject -c n" (where n=0 to 3) to
select disks.
Not extensively tested. This appears as 7 separate devices
/dev/sr0 through /dev/sr6 (your mileage may vary if you have other
scsi CD-ROM's).
This works fine with linux although you do not have full control over
the autoloader. Each time you "eject" the tape, the autoloader
will automatically load the next tape. There is a dip switch on the
autoloader which determines whether the autoloader will go back to
the first tape or just go offline when you load the last tape. You
cannot seek to random tapes in the magazine, with existing utilities.
I have one of these installed on my primary development machine
at DBD. This works just fine, so far. Plugged it to the
external SCSI bus and started using it. I didn't even shut the machine
down, although I think I rmmod'ed the scsi driver before and insmod'ed
it after; be careful not to short termination power or attach a
device to an active scsi bus (particularly one with a hard drive on it)
or you risk corrupting data and crashing your machine.
Information on using this under linux can be found on
my QV-10A page
This works using the QVPlay
software availible off the net. The documentation and FAQ are in japanese
but it is pretty easy to get the software to compile and run without
docs. Casio, the company, is pretty worthless. The newer models
in this line should also work (QV-100, QV-300, etc.).
Some other brands of cameras which store their images in standard
JPEG files on either floppy (Sony Mavica) or PCMCIA or compact
flash cards might also be usable with linux.
Use Aladin ghostscript 5.X and disable EPP/ECP mode.
I had some problems printing color with these printers with the gnu versions
although several other things have changed so the new version might not
be necessary. Configuring the parallel port in EPP or ECP mode might
cause problems with these printers. I have gotten some pretty good color
images out of these printers.
AMI BIOS is inferior to the award bios and causes problems
with sophisticated hardware such as the Tulip based Adaptec Cogent
4 port ethernet cards which use PCI to PCI bridges. Tolerable for
a simple workstation or a web server but not for serious hardware.
Actually, I haven't used these but I did do
some research on them. They are supported in ghostscript 5.X.
I haven't used these, but I have looked into it and both the color
and grayscale parallel port versions work using software availible on the net.
Note that the 2940AU is not completely compatible with older 2940
controllers. You need a special boot disk for redhat 4.0. Redhat 4.2
works fine. There are also some general problems with SCSI controllers
as loadable modules and other problems in 4.0 that may necessitate
using a boot disk other than the normal one supplied by redhat.
Also, note that if you are just using a tape drive or CD-ROM or
other infrequently accessed devices, that kerneld will unload the
driver causing the system to hang for 20 seconds while the new
driver loads and resets the SCSI bus the next time you use it;
to fix, just load the module with insmod, that way it will stay
loaded even when idle.
You can't install redhat 4.0 (or was it 3.3) via NFS or FTP over
the ethernet on this card using an unmodified boot disk because you
need to edit the /etc/pcmcia/config file. Newer versions probably will
work ok.
This is supported using a little package called
http://heyu.tanj.com/heyu/index.html. There is some
corrected protocol documentation by someone who is working on a
different x10 control program.
This works but is a bit of a pain to set up because it is a Plug
and Pray card and you also need to recompile the kernel.
I have not gotten this device to work yet, even though it
is supposedly compatible with the parallel to SCSI converter
contained in ZIP drives. I haven't played with this much yet.
Detailed info is on a separate page.
kermit
set line ________
c
ATUPX
^\c (control-\ c to escape to command mode again
redirect sx o288.119
#answer, with power on defaults
AT&F*M1&L1E0Q1L2M1&T4*F1*E1&D0S35.1=1S2=255&W0Z0O
#originate, with power on defaults
AT&F*M0&L1E0Q1L2M1&T4*F1*E1&D0S35.1=1S2=255&W0Z0O
AT = attention
&F = reset everything to factory defaults
*M0 = leased line auto-handshake in originate
*M1 = leased line auto-handshake in answer
&L1 = leased line mode, 2 wire leased line
E0 = no command echo
Q1 = quiet
L2 = volume during connect (adjust to suit).
M1 = speaker on until carrier is detected
&T4 = Grant Remote Digital Loopback request from remote modem
*F1 = accept remote configuration (requires &T4)
*E1 = if error control negotiation fails, disconnect the call
&D0 = DTR ignore DTR signal
S35.1 = Disable aborting from terminal during modem handshaking
S2=255 = disable escape code ("+++")
&W0 = write current configuration to non-volatile ram profile 0
Z0 = reset from profile 0
O = go online now
This file is maintained by Mark Whitis (whitis@freelabs.com).
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