3. Resolving installation and configuration problems

This section describes some of the most common failure modes for the PCMCIA subsystem. Try to match your symptoms against the examples. This section only describes ``general failures'' that are not specific to a particular card or driver.

It is nearly impossible to debug PCMCIA driver problems encountered when attempting to install Linux via a PCMCIA device. Even if you can identify the problem based on its symptoms, installation disks are difficult to modify, especially without access to a running Linux system. Customization of installation disks is completely dependent on the choice of Linux distribution, and is beyond the scope of this document. In general, the best course of action is to install Linux using some other means, obtain the latest PCMCIA drivers, and then debug the problem if it persists.

3.1 Base PCMCIA kernel modules do not load

Symptoms:

• Kernel version mismatch errors are reported when the PCMCIA startup script runs.
• After startup, lsmod does not show any PCMCIA modules.
• cardmgr reports ``no pcmcia driver in /proc/devices'' in the system log.

Kernel modules contain version information that is checked against the current kernel when a module is loaded. The type of checking depends on the setting of the CONFIG_MODVERSIONS kernel option. If this is false, then the kernel version number is compiled into each module, and insmod checks this for a match with the running kernel. If CONFIG_MODVERSIONS is true, then each symbol exported by the kernel is given a sort of checksum. These codes are all compared against the corresponding codes compiled into a module. The intent was for this to make modules less version-dependent, because the checksums would only change if a kernel interface changed, and would generally stay the same across minor kernel updates. In practice, the checksums have turned out to be even more restrictive, because many kernel interfaces depend on compile-time kernel option settings. Also, the checksums turned out to be an excessively pessimistic judge of compatibility.

Some of the PCMCIA modules require kernel services that may or may not be present, depending on kernel configuration. For instance, the SCSI card drivers require that the kernel be configured with SCSI support, and the network drivers require a networking kernel. If a kernel lacks a necessary feature, insmod may report undefined symbols and refuse to load a module.

The practical upshot of this is that kernel modules are closely tied to both the kernel version, and the setting of many kernel configuration options. Generally, a set of modules compiled for one 2.0.31 kernel will not load against some other 2.0.31 kernel unless special care is taken to ensure that the two were built with similar configurations. This makes distribution of precompiled kernel modules a tricky business.

You have several options:

• If you obtained precompiled drivers as part of a Linux distribution, verify that you are using an unmodified kernel as supplied with that distribution. If you intend to use precompiled modules, you generally must stick with the corresponding kernel.
• If you have reconfigured or upgraded your kernel, you will probably need to compile and install the PCMCIA package from scratch. This is easily done if you already have the kernel source tree installed. See the PCMCIA-HOWTO for detailed instructions.
• In some cases, incompatibilities in other system components can prevent correct loading of kernel modules. If you have upgraded your own kernel, pay attention to the ``minimal requirements'' for module utilities and binutils listed in the Documentation/Changes file in the kernel source code tree.

3.2 Interrupt scan failures

Symptoms:

• The system locks up when the PCMCIA drivers are loaded, even with no cards present.
• The system log shows a successful PCMCIA controller probe just before the lock-up, but does not show interrupt probe results.

After identifying the PCMCIA controller, the socket driver probes for free interrupts. The probe involves programming the controller for each apparently free interrupt, then generating a ``soft'' interrupt, to see if the interrupt can be detected correctly. In some cases, probing a particular interrupt can interfere with another system device.

The reason for the probe is to identify interrupts which appear to be free (i.e., are not reserved by any other Linux device driver), yet are either not physically wired to the PCMCIA controller, or are connected to another device that does not have a driver.

There are two ways to proceed:

• The interrupt probe can be restricted to a list of interrupts using the irq_list parameter for the socket drivers. For example, ``irq_list=5,9,10'' would limit the scan to three interrupts. All PCMCIA devices will be restricted to using these interrupts (assuming they pass the probe). You may need to use trial and error to find out which interrupts can be safely probed.
• The interrupt probe can be disabled entirely by loading the socket driver with the ``do_scan=0'' option. In this case, a default interrupt list will be used, which avoids interrupts already allocated for other devices.

In either case, the probe options can be specified using the PCIC_OPTS definition in the PCMCIA startup script, for example:

PCIC_OPTS="irq_list=5,9,10"

3.3 Memory probe failures

Symptoms:

• The core drivers load correctly when no cards are present, with no errors in the system log.
• The system freezes and/or reboots as soon as any card is inserted, before any beeps are heard.

Or alternately:

• All card insertions generate a high beep followed by a low beep.
• All cards are identified as ``anonymous memory cards''.
• The system log reports that various memory ranges have been excluded.

The core modules perform a memory scan at the time of first card insertion. This scan can potentially interfere with other memory mapped devices. Also, pre-3.0.0 driver packages perform a more aggressive scan than more recent drivers. The memory window is defined in /etc/pcmcia/config.opts. The default window is large, so it may help to restrict the scan to a narrower range. Reasonable ranges to try include 0xd0000-0xdffff, 0xc0000-0xcffff, 0xc8000-0xcffff, or 0xd8000-0xdffff.

If you have DOS or Windows PCMCIA drivers, you may be able to deduce what memory region those drivers use. Note that DOS memory addresses are often specified in ``segment'' form, which leaves off the final hex digit (so an absolute address of 0xd0000 might be given as 0xd000). Be sure to add the extra digit back when making changes to /etc/pcmcia/config.opts.

3.4 Failure to detect card insertions and removals

Symptoms:

• Cards are detected and configured properly if present at boot time.
• The drivers do not respond to insertion and removal events, either by recording events in the system log, or by beeping.

In most cases, the socket driver (i82365 or tcic) will automatically probe and select an appropriate interrupt to signal card status changes. The automatic interrupt probe doesn't work on some Intel-compatible controllers, including Cirrus chips and the chips used in some IBM ThinkPads. If a device is inactive at probe time, its interrupt may also appear to be available. In these cases, the socket driver may pick an interrupt that is used by another device.

With the i82365 and tcic drivers, the irq_list option can be used to limit the interrupts that will be tested. This list limits the set of interrupts that can be used by PCMCIA cards as well as for monitoring card status changes. The cs_irq option can also be used to explicitly set the interrupt to be used for monitoring card status changes.

If you can't find an interrupt number that works, there is also a polled status mode: both i82365 and tcic will accept a poll_interval=100 option, to poll for card status changes once per second. This option should also be used if your system has a shortage of interrupts available for use by PCMCIA cards. Especially for systems with more than one PCMCIA controller, there is little point in dedicating interrupts for monitoring card status changes.

All these options should be set in the PCIC_OPTS= line in either /etc/rc.d/rc.pcmcia or /etc/sysconfig/pcmcia, depending on your site setup.

3.5 Resource conflict between two cards

Symptoms:

• Two cards each work fine when used separately.
• When both cards are inserted, only one works.

This usually indicates a resource conflict with a system device that Linux does not know about. PCMCIA devices are dynamically configured, so, for example, interrupts are allocated as needed, rather than specifically assigned to particular cards or sockets. Given a list of resources that appear to be available, cards are assigned resources in the order they are configured. In this case, the card configured last is being assigned a resource that in fact is not free.

Check the system log to see what resources are used by the non-working card. Exclude these in /etc/pcmcia/config.opts, and restart the cardmgr daemon to reload the resource database.

3.6 Device configuration does not complete

Symptoms:

• When a card is inserted, exactly one high beep is heard.
• Subsequent card insertions and removals may be ignored.

This indicates that the card was identified successfully, however, cardmgr has been unable to complete the configuration process for some reason. The most likely reason is that a step in the card setup script has blocked. A good example would be the network script blocking if a network card is inserted with no actual network hookup present.

To pinpoint the problem, you can manually run a setup script to see where it is blocking. The scripts are in the /etc/pcmcia directory. They take two parameters: a device name, and an action. The cardmgr daemon records the configuration commands in the system log. For example, if the system log shows that the command ``./network start eth0'' was the last command executed by cardmgr, the following commands would trace the script:

cd /etc/pcmcia
sh -x ./network start eth0