13. Frequently Asked Questions
In this final chapter I've included som frequently asked
questions. This list should probably be much longer. Please let
me know if you have something to add.
13.1. XF68 or XF86
What is right, XF68 or XF86?
I have got a lot of questions conserning the name of the
X-server in the installation program mentioned in older
versions of this document. I have called it "XF68_FBDev". On
some CDs the server has got another name, "XF86_FBDev". The
reason for this naming convention and confusion is purely
historical. The Linux Frame Buffer Device was first developped
on m68k Macintoshes, and the XFree86 server for the device was
hence called XF68_FBDev. Later on the Frame Buffer Device was
ported to other platforms like the x86 clones and
PowerPC. What is the right name? The question is left as an
exercise for the reader.
13.2. There is "snow" on my X desktop
How can I configure X so it removes the "snow" on my desktop?
The easy answer is: You can't. The kernel frame buffer device
made by David Monro is still in an early stage, though working
very well. Distortions in the picture when moving the mouse
or scrolling a window are perfectly normal at eg
1024x768@60Hz. If you are a hacker, please fix it and post a
patch to David or Leigh. We would all love it very much. note that
lower resolutions like 800x600 og even 640x480 works great.
And no, there are only 8bit colors availble.
13.3. I can't get my hardware to work
How can I get my new ultra whizbang XYZ card to work?
The 7248 is a PC-like box with ISA and PCI interfaces, so one
should think that using "normal" PC hardware made for the x86
platform should work flawlessly. Sadly to say, it doesn't
always do. The drivers often have to be ported, and there are
not that many Carolina motherboard kernel hackers out
there. In addition, much hardware made for the x86 platforms
uses BIOS calls to work properly. As the 7248 and its
relatives does not have such a BIOS, it's extremely difficult
to get this hardware to run under Linux.
That said, there are working hardware for this box that runs
with Linux. For questions about this, please contact the
Workstation list, see Section 11.
Update: With the latest versions of the Linux 2.4 bk
development tree (NOT the official Linux 2.4 sources), many of
the problems stated above are fixed, and much more hardware is
supported. For example did I put a standard eepro100 card in
my box, and it worked flawlessly. This means you can use the
7248 for example as a packet-filtering firewall. I've also
heard rumours on plain standard ISA Soundblaster cards
working. Try and see if your card works. If it's interesting,
send me an email, and I'll put a note here. See Section 9 for notes on building and installing a
2.4 kernel.
13.4. The PReP boot partition?
Where should I mount the PReP boot partition?
To be able to understand the answer for this question, it's
important that the reader understands how the 7248 boots into
Linux. This is a three step procedure. First, the Firmware
(which behaves in the same way as a PC BIOS) looks for
something to boot. Usually, it should check the floppy drive,
the CD drive, and then the first SCSI disk. On the SCSI disk
it will look for a special partition called a PReP boot
partition. On this partition, it will read the first program
it can find there. If this is a Linux kernel bootloader, it
will read and run this, and then the bootloader boots
Linux. From here, Linux is in charge.
Many have asked where they should mount the PReP boot
partition (the type 41 partition). This is a common
misunderstanding. The PReP boot partition, usually located on
/dev/sda1, should NOT be mounted anywhere. The files on this
partition, usually only a single Linux kernel with a static
linked kernel bootloader, are only used by the firmware when
booting. The operating system does not use these files after
the kernel has booted, so there is no need for mounting that
partition.
Some people mix the meaning of the /boot directory and the PReP
boot partition. Both use to contain kernels, but their use are
different. /boot is used for storing kernels for later use,
and for bookholding system info. The /boot directory is NOT
read by the Firmware at boot time, so changing the contents of
this directory does not change the way the Firmware loads
Linux.
To be able to load a new kernel, you have to replace the
existing kernel on the PReP partition. This is done with the
dd command, see Section 9 for details.
13.5. It won't boot at all. Could it be bad RAM?
The machine won't boot at all. I suspect the RAM could be the
problem. What kind of RAM should I use for this box?
The 7248 and it's cousines with Carolina motherboard do use
special RAM, more specifically, they use only parity RAM. The
spesifications are as follows: 72-pin SIMM, 5 Volt, Fast Page
Memory with Parity, 70 ns. David Monro states that is is
possible to make Carolinas work with other types of RAM if you
remove the cache. Look at Section 11 for
details.
13.6. Kernel boots, but stops at "Parity checking"
And now I thought it would work, but it stops at "Parity
checking". I can't get a step further. Can you help me,
please? Has this something to do with bad RAM chips? Or is it
something wrong with my scsi devices?
You use a 2.2 kernel, don't you?
This message comes from the SCSI subsystem, so it has nothing
to do with your RAM. Sometimes, by uknown reason, the Linux
NCR driver in the 2.2-series caused the scsi controller to
hang in some uninterruptible state, which endured, even
bypassing reboot. The solution then was to boot AIX or even
Windows NT for PPC (yes, such a beast exists, but you really
don't want it), which resat the controller in proper
condition. Alternatively, switch off the machine, pull out the
battery inside, let it stay out for a couple of weeks or so,
and fit things back together. The 2.4 driver fixed this
problem.
Boot a 2.4 kernel, and you should be allright.
This could of course also be a real SCSI parity problem. If a
2.4 kernel doesn't help, check your SCSI devices for wireing
and termination problems.