FreeDOS kernel with memdisk support compiled in:

When enabled one can supplement (or replace) CONFIG.SYS from the memdisk
command line.  The kernel upon booting will verify running on a 386+ and
then check for memdisk using int 13h call with magic values.  If found
then the memdisk command line is processed and simulated CONFIG.SYS lines
are evaluated left to right as though they logically followed the last
line in CONFIG.SYS (or FDCONFIG.SYS).

Example syslinux.cfg section:
LABEL FreeDOS
  KERNEL memdisk
  MENU LABEL FreeDOS example
  INITRD FDSTD.img
  APPEND {ECHO Booting FreeDOS}{ECHO This is the second line.}


FreeDOS config lines are denoted by surrounding the line in curly braces {}
thus allowing multiple simulated lines on a single APPEND line.  However,
the closing brace } may be omitted if it would be immediately followed by
an opening brace { or end of the APPEND line.  Anything on the memdisk line
outside of the curly braces {} is ignored.  The lines may be preceeded by 
FD= to be compatible with earlier FD kernel release or any other key= to
specify the environment variable generated by getargs utility.  All simulated
config lines (text between the { and }) are evaluated by the kernel asis 
except the final line (the line within final {}).  

The final } is optional which results in the memdisk options initrd= and 
BOOT_IMAGE= to appear as part of the config.sys line.  To avoid issues
several memdisk options are ignored if after the last opening brace {.  
Note that the syslinux/memdisk options are case sensitive.  Currently
ignored options are: initrd, BOOT_IMAGE, floppy, harddisk, and iso.

Additionally, to simplify passing and overriding arguments when syslinux
is booting, any key=value pairs seen after any memdisk options will cause
all corresponding key=??? prior to any memdisk options to be cleared on
the resulting config line.  
For example if the final assembled memdisk line appears to the kernel as:
{ECHO HI{ECHO X=1 X=2 Y=1 Z=1 initrd=FDSTD10.img BOOT_IMAGE=memdisk X=386
then the following two lines will evaluated by the kernel after processing
any CONFIG.SYS lines.
ECHO HI
ECHO         Y=1 Z=1 X=386

The following APPEND lines are all treated identically by the kernel.
APPEND floppy FD={ECHO Welcome}{ECHO 2nd line}{ECHO third}
APPEND floppy FD={ECHO Welcome{ECHO 2nd line{ECHO third
APPEND {ECHO Welcome}    {ECHO 2nd line}   {ECHO third} floppy
APPEND {ECHO Welcome{Echo 2nd line}   {ECHO third floppy
resulting in the following equivalent three CONFIG.SYS lines
ECHO Welcome
ECHO 2nd line
ECHO third


The following complete example syslinux.cfg and FreeDOS configuration files
could be used to boot various kernel options avoiding the use of the FreeDOS
kernel menu in addition to the Sylinux menu.

# CONFIG.SYS
REM always executed, in common with all choices
FILES=20
LASTDRIVE=Z
SHELLHIGH=\COMMAND.COM /E:256 /P


#AUTOEXEC.BAT
@ECHO OFF
CLS
ECHO Welcome to FreeDOS (http://www.freedos.org)!
ECHO User selected menu %CONFIG%


# SYSLINUX.CFG
UI vesamenu.c32
DEFAULT clean

LABEL clean
MENU LABEL FreeDOS with no drivers
KERNEL memdisk
INITRD /fdos0360.img
APPEND floppy FD={SET config=0}

LABEL jemm
MENU LABEL FreeDOS with memory manager
KERNEL memdisk
INITRD /fdos0360.img
APPEND floppy FD={SET config=1}{DEVICE?=JEMMEX.EXE


Syslinux boot-prompt (when vesamenu not used):
jemm
or
jemm NOEMS