3.1.1. Kernel Options in Linux 2.0 and Higher
After the general option section is complete, the configuration will go on to ask whether you want to include support for various features, such as SCSI drivers or sound cards. The prompt will indicate what options are available. You can press ? to obtain a description of what the option is actually offering. You'll always have the option of yes (y ) to statically include the component in the kernel, or no (n ) to exclude the component completely. You'll also see the module (m ) option for those components that may be compiled as a run-time loadable module. Modules need to be loaded before they can be used, and are useful for drivers of components that you use infrequently.
The subsequent list of questions deal with networking support. The exact set of configuration options is in constant flux due to ongoing development. A typical list of options offered by most kernel versions around 2.0 and 2.1 looks like this:
*
* Network device support
*
Network device support (CONFIG_NETDEVICES) [Y/n/?]
You must answer this question with y if you want to use any type of networking devices, whether they are Ethernet, SLIP, PPP, or whatever. When you answer the question with y , support for Ethernet-type devices is enabled automatically. You must answer additional questions if you want to enable support for other types of network drivers:
PLIP (parallel port) support (CONFIG_PLIP) [N/y/m/?] y
PPP (point-to-point) support (CONFIG_PPP) [N/y/m/?] y
*
* CCP compressors for PPP are only built as modules.
*
SLIP (serial line) support (CONFIG_SLIP) [N/y/m/?] m
CSLIP compressed headers (CONFIG_SLIP_COMPRESSED) [N/y/?] (NEW) y
Keepalive and linefill (CONFIG_SLIP_SMART) [N/y/?] (NEW) y
Six bit SLIP encapsulation (CONFIG_SLIP_MODE_SLIP6) [N/y/?] (NEW) y
These questions concern the various link layer protocols that Linux supports. Both PPP and SLIP allow you to transport IP datagrams across serial lines. PPP is actually a suite of protocols used to send network traffic across serial lines. Some of the protocols that form PPP manage the way that you authenticate yourself to the dial-in server, while others manage the way certain protocols are carried across the link—PPP is not limited to carrying TCP/IP datagrams; it may also carry other protocol such as IPX.
If you answer y or m to SLIP support, you will be prompted to answer the three questions that appear below it. The compressed header option provides support for CSLIP, a technique that compresses TCP/IP headers to as little as three bytes. Note that this kernel option does not turn on CSLIP automatically; it merely provides the necessary kernel functions for it. The Keepalive and linefill option causes the SLIP support to periodically generate activity on the SLIP line to avoid it being dropped by an inactivity timer. The Six bit SLIP encapsulation option allows you to run SLIP over lines and circuits that are not capable of transmitting the whole 8-bit data set cleanly. This is similar to the uuencoding or binhex technique used to send binary files by electronic mail.
PLIP provides a way to send IP datagrams across a parallel port connection. It is mostly used to communicate with PCs running DOS. On typical PC hardware, PLIP can be faster than PPP or SLIP, but it requires much more CPU overhead to perform, so while the transfer rate might be good, other tasks on the machine may be slow.
The following questions address network cards from various vendors. As more drivers are being developed, you are likely to see questions added to this section. If you want to build a kernel you can use on a number of different machines, or if your machine has more than one type of network card installed, you can enable more than one driver:
.
.
Ethernet (10 or 100Mbit) (CONFIG_NET_ETHERNET) [Y/n/?]
3COM cards (CONFIG_NET_VENDOR_3COM) [Y/n/?]
3c501 support (CONFIG_EL1) [N/y/m/?]
3c503 support (CONFIG_EL2) [N/y/m/?]
3c509/3c579 support (CONFIG_EL3) [Y/m/n/?]
3c590/3c900 series (592/595/597/900/905)* License
