Notes about PCMCIA in the 2.4 kernel PCMCIA kernel driver support is now included in the 2.4 linux kernel tree. While it shares most of the same code with the standalone PCMCIA driver package, there are some important differences. The kernel PCMCIA support is also still evolving. This README is up to date as of the 2.4test7-pre* kernels. The kernel PCMCIA support does not eliminate the need to install the pcmcia-cs package. Kernel PCMCIA still requires the same user tools (cardmgr, cardctl, /etc/pcmcia/* files). To use the kernel PCMCIA drivers, configure the kernel with CONFIG_PCMCIA ("CardBus support") enabled. In this case, "CardBus" really refers to the type of host bridge supported: both 16-bit and CardBus card support is included. The drivers can either be built into the kernel or built as modules. For now, only PCI-to-CardBus bridges are supported, so there are no options for choosing bridge drivers. PCMCIA client driver options are listed in their regular driver categories; thus, PCMCIA network drivers are in a submenu of network drivers, and PCMCIA serial drivers are in a submenu of character drivers. The CardBus socket driver in the 2.4 tree is the "yenta_socket" driver. In your PCMCIA startup options, this driver should be specified in place of the old i82365 driver. When compiling the standalone PCMCIA package, the Configure script decides whether or not to build any kernel modules by looking at the value of the CONFIG_PCMCIA option. If CONFIG_PCMCIA is enabled, then no kernel components are built. If CONFIG_PCMCIA is disabled, then all the modules will be built and installed. It is safe to compile the user tools (cardmgr, cardctl, etc) in a PCMCIA package whose version number differs from the PCMCIA version number in the kernel source tree. The kernel PCMCIA header files take precedence over the ones included in the PCMCIA package, if CONFIG_PCMCIA is enabled. The following tables show the correspondence between PCMCIA client driver names, and kernel configuration options. Network drivers: 3c589_cs 3Com 3c589 CONFIG_PCMCIA_3C589 3c574_cs 3Com 3c574 CONFIG_PCMCIA_3C574 fmvj18x_cs Fujitsu FMV-J18x CONFIG_PCMCIA_FMVJ18X pcnet_cs NE2000 compatible CONFIG_PCMCIA_PCNET nmclan_cs New Media CONFIG_PCMCIA_NMCLAN smc91c92_cs SMC 91Cxx CONFIG_PCMCIA_SMC91C92 xirc2ps_cs Xircom 16-bit CONFIG_PCMCIA_XIRC2PS ibmtr_cs IBM PCMCIA tokenring CONFIG_PCMCIA_IBMTR ray_cs Aviator/Raytheon 2.4MHz CONFIG_PCMCIA_RAYCS netwave_cs Xircom Netwave AirSurfer CONFIG_PCMCIA_NETWAVE wavelan_cs AT&T/Lucent Wavelan CONFIG_PCMCIA_WAVELAN Character drivers: serial_cs PCMCIA serial device CONFIG_PCMCIA_SERIAL_CS serial_cb CardBus serial device CONFIG_PCMCIA_SERIAL_CB SCSI low-level drivers: aha152x_cs Adaptec AHA152X CONFIG_PCMCIA_AHA152X qlogic_cs Qlogic CONFIG_PCMCIA_QLOGIC fdomain_cs Future Domain CONFIG_PCMCIA_FDOMAIN apa1480_cb Adaptec APA1480 CardBus CONFIG_PCMCIA_APA1480 The CardBus network drivers (3c575_cb, tulip_cb, epic_cb) have been folded into the corresponding PCI drivers using the new hot plug PCI interface. The tulip_cb driver has been partially merged into the tulip driver ('DECchip Tulip (dc21x4x)', CONFIG_TULIP). Xircom CardBus cards are supported by a separate driver ('Xircom Tulip-like CardBus', CONFIG_PCMCIA_XIRTULIP). The 3c575_cb driver is merged into the 3c59x driver ('3C590/3c900 series (592/595/597) "Vortex/Boomerang" support', CONFIG_VORTEX). And the epic_cb driver has been folded into the epic100 driver ('SMC EtherPower II', CONFIG_EPIC100). Known problems and limitations: o ISA-to-PCMCIA and PCI-to-PCMCIA bridges are not supported. The bridge driver interface in 2.4 is significantly different, and the tcic and i82365 drivers have not been ported to the new interface. o Some of the less popular client drivers, like the memory card drivers, have not been ported into the 2.4 driver tree yet. o The yenta_socket driver does not have the /proc interface of the i82365 driver, so the dump_exca and dump_cardbus tools do not work. It actually has no debugging support at all. o The kernel PCMCIA package cannot be configured to use PnP BIOS calls for resource management. This will not be fixed, but this is rarely a serious issue. o There is a somewhat serious API issue with the new "PCI hot plug" interface used by the new tulip and 3c59x drivers. It is unable to pass device name information to cardmgr, so the PCMCIA configuration scripts don't work. Fixing this properly is non-trivial, because the new API is not intended to be tightly linked to the PCMCIA card control interface at all. A substitute for that interface, but for PCI hot plug, has not really been sketched out yet. Answers to some common questions: Q: Are these two versions of PCMCIA both going to continue with active development? A: The way I see things now, the kernel PCMCIA subsystem will probably be too unstable for widespread deployment, at least in the early days of 2.4. So the standalone package will probably be widely used for some time yet. However, the kernel PCMCIA subsystem should eventually stabilize and be the focus of new development. So, I think development for the standalone kernel modules will shift away from adding functionality, towards mainly bug fixes. Q: Which should I use / which is better? The kernel PCMCIA, or the standalone PCMCIA? A: It really depends. The client drivers should generally behave the same. Some of the internals of the kernel PCMCIA system are very different and less mature than the standalone drivers. Some legacy hardware is currently only supported by the standalone drivers. At this point, I'd recommend using the kernel drivers if you have a specific need or if you are interested in helping test and debug. If you mainly just want something that works, then the standalone subsystem is probably a better bet at the moment. Q: What should I do as a driver developer? A: Again it really depends. I will probably be really picky about including significant new functionality in the standalone PCMCIA package; I expect that the kernel PCMCIA package will stabilize and take over perhaps in the 2.5 kernel timeframe. It might make the most sense to develop contributed drivers for the standalone package first because it is a stable platform; and then port to 2.4. Q: I'm using the kernel PCMCIA subsystem but want to use a driver that isn't included in the kernel yet. Why can't I compile that driver from the standalone PCMCIA package? A: The Makefiles are set up to discourage this, mainly to prevent people from trying combinations that don't make sense. Things in the "modules" directory of the standalone package will not work with the kernel PCMCIA subsystem. However, you can build client drivers by doing a "make" in either the "clients" or "wireless" subdirectories. Q: Who is maintaining the kernel PCMCIA subsystem? A: I am not playing as central a role in maintaining the kernel modules as I have with the standalone package. I have periodically updated some of the core modules and client drivers with fixes from the standalone package. Linus Torvalds wrote the yenta_socket driver more or less from scratch and he has been maintaining that bit. Jeff Garzik has been working on the hot plug PCI adaptations for the tulip_cb, 3c575_cb, and epic_cb drivers.