4.3. Configure the SYSLINUX boot
loader
SYSLINUX
is a boot loader that is installed on a MS-DOS floppy disk. As
directed by it's configuration file
\SYSLINUX.CFG it will load one of the files
from the floppy disk as a Linux kernel.
SYSLINUX presents a simple text
interface that can be used to select between canned configurations
defined in the configuration file and can be used to add parameters
to the kernel.
ISOLINUX and
PXELINUX are variants of
SYSLINUX for CD-ROMs and Intel's Preboot
Execution Environment.
SYSLINUX supports a variety of
serial port speeds, but it only supports eight data bits, no parity
and one stop bit. SYSLINUX supports the
serial ports COM1: through
to COM4:, as with most boot
loaders these are written as port 0 through to
port 3.
For SYSLINUX to support a serial
console add a new first line to
\SYSLINUX.CFG:
The variables are the same as used by syntax descriptions in
Figure 2-7 and Figure 4-2 plus those in Figure 4-12.
The <syslinux_flow_control>
variable controlling the RS-232 status and flow
control signals is optional. If your null-modem cable does not
present any status or handshaking signals then do not use it. The
value of <syslinux_flow_control>
is calculated by adding the hexadecimal values for the desired flow
control behaviours listed in Table 4-1.
The behaviours for a correctly-wired null-modem cable or a
correctly configured modem are marked "Required for full
RS-232 compliance" in the table. The sum
of these values is 0xab3.
Table 4-1. SYSLINUX flow control
bitmap
Flow control behaviour | Hex value | Required for full RS-232
compliance? |
|---|
Assert DTR | 0x001 | Yes |
Assert RTS | 0x002 | Yes |
Wait for CTS assertion | 0x010 | Yes |
Wait for DSR assertion | 0x020 | Yes |
Wait for RI assertion | 0x040 | No |
Wait for DCD assertion | 0x080 | Yes |
Ignore input unless CTS asserted | 0x100 | No |
Ignore input unless DSR asserted | 0x200 | Yes |
Ignore input unless RI asserted | 0x400 | No |
Ignore input unless DCD asserted | 0x800 | Yes |
Our preferred configuration of 9600bps,
port 0, full RS-232 status
signals and CTS/RTS flow
control is written as:
 | When using this configuration SYSLINUX
will not display anything and will not accept any typed character
until the RS-232 status signals show a
connected modem call (or a connected terminal if you are using a
null-modem cable). |
If you have a null modem cable with no RS-232 status signals
and no flow control then use:
Remember that the serial command must be
the first line in \SYSLINUX.CFG.
Take our 
