Mobile Linux users take advantage of notebook PCMCIA slots to add 70-pin, credit-card-sized devices to support ethernet LAN connectivity, wireless operations, FireWire devices, CompactFlash hard drives, external storage devices, serial ports, and modems. Many different types of PCMCIA cards and CompactFlash form-factor cards in a PCMCIA caddy are supported by the Linux kernel and David Hinds's Card Services software.
Power is provided to PCMCIA devices and adapters directly through the card slot, although some external hardware might require an additional power source. PCMCIA support is enabled and configured at boot time. With the newer Linux kernels, however, support is provided by kernel modules or direct Linux kernel support.
The PCMCIA Card Services software provides diagnostic information by one or more high or low beeps upon card insertion. One high and one low beep indicate that a card is recognized but failed to be configured. A single beep indicates that the card was only recognized. Two high beeps indicate that a card was recognized and configured.
For example, if you use a CompactFlash storage device and insert it into your notebook while using Ubuntu, you should hear two high beeps. You can then check to see what device has been assigned to the card by using the dmesg command:
$ dmesg hde: SunDisk SDCFB-8, ATA DISK drive ide2 at 0x100-0x107,0x10e on irq 3 ide-floppy driver 0.99.newide hde: 15680 sectors (8 MB) w/1KiB Cache, CHS=245/2/32 hde: hde1
Not all the output is shown here (and yours might look different), but this example shows that the card has been recognized and configured as the /dev/hde device (with a single partition, /dev/hde1). You can then use the device as any other storage medium.
Other devices can be similarly recognized and configured. For example, if you have a combination ethernet and modem PCMCIA card and insert it into your notebook, you should hear two sets of high beeps (to indicate successful recognition and configuration of the network interface and modem). The Linux kernel will report the interface and device information:
$ dmesg eth0: NE2000 (DL10019 rev 05): io 0x300, irq 3, hw_addr 00:E0:98:06:84:C5 ttyS04 at port 0x0af8 (irq = 3) is a 16450
Here, the network interface has been recognized as eth0 (see Chapter 18, to see how to connect to a network). The modem is configured to use /dev/ttys04.
Again, troubleshooting problems with PCMCIA cards can be difficult, especially with the explosion in popularity and type of 802.11b/g wireless networking cards. Such troubleshooting is likely to require downloading, building, and installing new drivers.
Fortunately, however, nearly all serial, modem, and CompactFlash storage cards are easily recognized and configured. Many ethernet cards are also supported. To check on the current support status for many cards, read the file supported.cards. You will find a copy under the
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