Linux PCMCIA Card Services is a series of applications and kernel modules that should be built along with any kernel you compile or install. In stock Redhat Linux, there is a pcmcia-cs package that complements the stock kernels. However, as you will probably want to build your own (presumbly more recent) kernel for APM support, you will need to build PCMCIA modules for any kernel you build yourself. Mercifully, this is as simple as untarring the sources obtained from the Linux PCMCIA Home Page and typing make config, answering a few questions, then make all and make install. Really!

Regardless of whether you roll your own PCMCIA Card Services or use the stock ones provided in the Redhat distribution, you will want to make the following modifications to ensure that it works correctly on your ThinkPad 390E:

• In /etc/sysconfig/pcmcia, you will likely find that PCMCIA is disabled by default. You will want to turn this on and tell PCMCIA which controller type you have (on the Thinkpads, it's almost universally an i82365 chipset). You can also force-feed PCMCIA a list of IRQ's it's allowed to use, and can disable its internal scanning of IRQ's. My /etc/sysconfig/pcmcia file looks like the following:

        PCMCIA=yes
        PCIC=i82365
        PCIC_OPTS="irq_list=3 do_scan=0"
        CORE_OPTS=
        CARDMGR_OPTS=
        

• In /etc/pcmcia/config.opts, there are several include... lines at the top of the file which specify the addresses that PCMCIA will probe for conflicting devices on. However, this probe will often not detect latent hardware (like Winmodems) that are silently appropriating IO ports and addresses. I limit the scanned range to the following:

        include port 0x100-0x2f0, port 0x300-0x4ff, port 0x1000-0x17ff
        include memory 0xd0000-0xfffff
        include memory 0x60000000-0x60ffffff
        

  In particular, this eliminates the port range 0x2F8 - 0x2FF, which conflicts with the "hidden" Winmodem. This alteration is typically necessary for PCMCIA to work well on most new Thinkpads.

• If you use a PCMCIA ethernet card, the /etc/pcmcia/network.opts file is modified by Redhat to be in sync with their netcfg and linuxconf configuration tools. Therefore, if you install genuine PCMCIA Card Services, it will no longer respond to changes you make in the Redhat graphical configuration tools. You can either enter your network configuration directly into /etc/pcmcia/network.opts and ignore Redhat's tools, or you can alter the PCMCIA /etc/pcmcia/network.opts to look like this:

        if [ -f /etc/sysconfig/network-scripts/ifcfg-eth0 ] ; then
          start_fn () {
                  /sbin/ifup $1
          }
          stop_fn () {
                  /sbin/ifdown $1
          }
        fi
        

  This alteration will allow you to use the Redhat configuration tools as before.

The Linux PCMCIA Home Page contains a very large list of supported cards for each stable release of the software. If you want to purchase a PCMCIA card for you laptop, make sure it's on this list. Most 16-bit cards work right out of the box, with the exception of a few flakey combo cards and PCMCIA Winmodems. An increasing number of 32-bit CardBus cards are now being supported actively as well.

My CardBus experiences: I purchased a 3Com MegaHertz 10/100 Mbps 32-bit CardBus ethernet card with XJack connector, model 3CXFE575BT. At the time, support for this card was "experimental", but even so, I was able to get it working admirably in both 10 and 100 Mbps modes, set to IRQ 3. 32-bit CardBus cards are really necessary to get the high throughput needed for high-speed SCSI and 100 Mbps ethernet cards. There are 100 Mbps cards in 16-bit format; however, few perform faster than 20 Mbps or so because of the bottleneck over the slow 16-bit PCMCIA bus. Support in Linux for Cardbus devices is immature but usable, and rapidly improving. Take note that as of version 3.0.14 of Card Services, only the 3c575_cb Cardbus driver supports suspend and resume cycles -- you will need to eject other Cardbus cards before suspending.

Notes about particular PCMCIA cards in the ThinkPad 390E

• The 3CXFE575BT and 3CCFE575BT ethernet cards will not work unless you disable PCI Power Management in the Thinkpad BIOS. This is true for all OS's, so apparently it is a bug in the 390E firmware. This appears to be the only card with a hardware exception so far.

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