Re: PCMCIA: unable to map memory

• Previous message: Marvin Massih: "NetGear MA401: "Destination Host Unreachable""
• In reply to: dhinds_at_sonic.net: "Re: PCMCIA: unable to map memory"
• Next in thread: Bill Marcum: "Re: PCMCIA: unable to map memory"
• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Date: Sat, 08 Nov 2003 19:37:18 +0100

> Remove the first badram range and leave just the new one.

Yes, I did so, and: it works great. I already
thought about it, because the BadRAM solution
worked OK with an excluded Ram area of 32kb
before, so it shouldn't need 64kb now.

Thanks for helping to work this out. I am really
happy to have solved this nasty problem after days
of confusion. :-)

It's the best to write the solution down while the
problem is still clear on mind. Therefore I add
now a summary, so everybody who wants to run a
recent linux on a compaq contura aero can profit
from this. I also will add the following text to
my website at http://ulihansen.kicks-ass.net/aero

Please everybody correct me if I mixed something
up or got something wrong.

Thanks again, Dave
Uli

-----summary of the problem and solution--------

Linux on the compaq contura aero may become
unstable on machines that have been upgraded to 20
MB RAM. This instability is caused by an invalid
access to specific memory addresses above 16 MB.
Linux conflicts here with the pcmcia-controller.

As workaround it is possible to run linux stable
if you limit the aeros RAM with "mem=16M" at boot
or by disabling PCMCIA. This is not satisfying. So
  let's take a look at the problem.

The invalid memory addresses can not be described
as a fixed memory hole - it is more like a
_shadow_, thrown by the controllers actually used
memory adresses into an area above 16 MB.

One aero-user, Donald Gordon suspects, that this
behaviour is caused by "incomplete address
decoding. Some parts of the system, including the
PCMCIA controller, may ignore the top 8 address
bits, thus causing a false image of (for instance)
the memory-mapped area used by the PCMCIA
controller to appear at 16mb + expected location".

This 'false image' or shadow in the > 16 MB RAM
adresses, thrown by the real memory addresses used
by the pcmcia controller, was irrelevant with
compaqs stock memory extension modules: They added
only 4 or 8 MB to the aeros soldered in
4MB-RAM-chips and gave it a max of 12 MB RAM.

With the production of third party (Kingston)
16-MB-RAM-Extension-Modules for the aero in the
late 90's, which gave the machine a max of 20 MB
RAM, this shadow became visible -and a problem for
linux users.

A problem that can be solved. Two things are here
important:

- An user-defined setting of the memory that
should be used by the pcmcia-controller. This can
be done with the line "include memory" in the
configuration file "/etc/pcmcia/config.opts" of
the pcmcia-cs-package by David Hinds. The package
must be installed if you want to use pcmcia with
kernel 2.2 or 2.4 and can be downloaded here:
http://pcmcia-cs.sourceforge.net/

- A patch for the kernel (2.2. or 2.4) called
BadRAM by Rick van Rein (and it's successor BadMEM
by Nico Schmoigl). It allows specifying the
appropriate RAM-Adresses in the 'shadowed area'
that should be avoided by linux.
The BadRAM -patch can be downloaded from here:
http://rick.vanrein.org/linux/badram/
BadMEM is found here:
http://badmem.sourceforge.net/
Applied patches for redhat stock-kernels (2.4) can
be found here:
http://dynamicnetservices.com/~will/badram/

1. Specifying the memory for the pcmcia-controller

With kernel 2.2 I used with success the
ram-addresses "0xb0000-0xb7fff". So try to specify
the ports and the memory that the
pcmcia-controller shall use in
/etc/pcmcia/config.opts with the following values:

include port 0x100-0x4ff, port 0xc00-0xcff
include memory 0xb0000-0xb7fff

All other "include memory"-statements must be
outcommented.

Kernel 2.4 (including BadRAM-patch) seems to react
more sensitive to the ram-map provided by the
aero's bios and reserves pages for the Video-RAM
that formerly were available for kernel 2.2. That
meant with kernel 2.4 we need to search a new free
RAM-adress-range for the pcmcia-controller. This
can be detected from /proc/iomem. So boot linux
with pcmcia disabled and command in the shell:

cat /proc/iomem

For me this created the following output:

00000000-0009efff : System RAM
000a0000-000bffff : Video RAM area
000c0000-000c7fff : Video ROM
000f0000-000fffff : System ROM
00100000-013fffff : System RAM
   00100000-00240c09 : Kernel code
   00240c0a-00283d5f : Kernel data

Kernel 2.2 used the memory range 0xb0000-0xb7fff.
Now, with Kernel 2.4 this range is reserved for
Video RAM and can not be used. Still free seem to
be the adress-range from Oxd0000 to 0xeffff. So
lets try out these addresses:

So set in /etc/pcmcia/config.opts

include port 0x100-0x4ff, port 0xc00-0xcff
include memory 0xd0000-0xd7fff

All other "include memory"-statements must be
outcommented. The above values work OK for me.

2. Configuring BadRAM

Now with specifying the memory-adresses for the
pcmcia-controller the work is NOT done. We must
keep in mind, that the memory range used by the
controller throws a shadow of unusable
ram-adresses into the > 16 MB range. These RAM
adresses have to be excluded, otherwise linux will
freeze if you enable pcmcia. This can be done with
the kernel-patches BadRAM or BadMEM.

Apply the appropriate BadRAM-patch for the kernel.
The patch "BadRAM-2.2.19.A1.patch" also works for
all above kernel 2.2-versions including 2.2.25.

For kernel 2.4 there are patches from different
contributers. I use the adapted version for the
newest redhat stock - kernel-source 2.4.20-20.9.
After patching the kernel you have a new
kernel-configuration-option under General setup
that is called
CONFIG_BADRAM=y
Please take care to enable that option.

Now specify the RAM-adresses you don't want to use:
either at boottime with the command
linux badram=value1,value2
or in lilo.conf with the line
append="badram=value1,value2"

The two values specify a so called V1-pattern.
value1 is supposed to be the first RAM-address to
exclude, value2 is a so called mask. So the second
value is NOT the last address to exclude but (as I
understand) a description of the geometrical form
of the RAM area that should be excluded. This is
OK for the original purpose of BadRAM: Using
defunct RAM-Modules. Defect areas of a RAM bank
don't stretch over a one coherent logical adress
range, they stretch over a geometrical area on the
physical ram-module.

A description (unfortunately in german) of these
patterns can be found in a report by Nico Schmoigl
for the Linux Magazin:

http://www.linux-magazin.de/Artikel/ausgabe/2001/11/badmem/badmem.html?print=y

Now how to find out the correct values?

The value2 was provided by Donald Gordon in his
mail to the aero-usergroup. It is 0xffff8000.

value1 depends on the address-range, specified in
/etc/pcmcia/config.opts for the pcmcia-controller.
If you used
include memory 0xb0000-0xb7fff
the correct value1 for BadRAM would be
0x010b0000.

So these are settings for Badram corresponding to
the settings for the pcmcia-controller in
/etc/pcmcia/config.opts:

config.opts corresponding BadRAM-statement

0xb0000-0xb7fff 0x010b0000,0xffff8000
0xd0000-0xd7fff 0x010d0000,0xffff8000
0xe0000-0xe7fff 0x010e0000,0xffff8000
and so on.

For instance with kernel 2.4 I have in
/etc/pcmcia/config.opts the line:
include memory 0xd0000-0xd7fff
So in lilo.conf I must use the line
append="badram=0x010d0000,0xffff8000"

Now we paid respect to the 'shadow' the
pcmcia-controller throws into the >16MB RAM-range,
we exclude these areas with the help of BadRAM and
can now (after a lilo -v) safely reboot the aero
and use pcmcia.

Conclusion

Running Linux on laptops meant once again that
users have to work around errors that were made by
the manufactures, in this case compaq. On the
other hand I can not blame them: They never
thought that the contura aero would once run with
more than 12 MB RAM and never dreamed of Red Hat 9
installed on it instead of windows 3.1. ;-)

My thanks go to David Hinds who helped with
practical tips for finding the correct RAM-values.
And to the linux-community for providing all the
information, knowledge and software.

Linux means learning. Thanks for helping. Hope
this may help others.

Uli

• Previous message: Marvin Massih: "NetGear MA401: "Destination Host Unreachable""
• In reply to: dhinds_at_sonic.net: "Re: PCMCIA: unable to map memory"
• Next in thread: Bill Marcum: "Re: PCMCIA: unable to map memory"
• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]