The boot loader in official m0n0wall images is configured to read
only one block at a time to work around incompatibilities between certain
brands of CF cards and BIOSes. Also, it's compiled not to use fancy
terminal emulation, as that usually messes up the output on a serial
console. If you're going to build an image for a generic PC, you may be
able to do without these modifications and just use the boot loader from
/boot that was installed with FreeBSD. Otherwise,
read on.
Edit /sys/boot/i386/libi386/Makefile and
comment out the line that says CFLAGS+=
-DTERM_EMU. Now apply the single-sector-read patch, if
desired:
cd /usr/src patch < $MWPATCHDIR/boot/boot.patch
When building a boot loader for WRAP boards,
boot1.s needs to be modified not to fiddle with gate
A20, since the WRAP doesn't have a keyboard controller:
patch < $MWPATCHDIR/boot/boot-wrap.patch
Compile the boot loader:
cd /sys/boot make clean && make obj && make
Make a directory somewhere to hold the boot files until you're ready to create the image, and copy the necessary files to it:
mkdir $BOOTDIR
cp /usr/obj/usr/src/sys/boot/i386/loader/loader $BOOTDIR
cp /usr/obj/usr/src/sys/boot/i386/boot2/{boot1,boot2} $BOOTDIR
cp /usr/obj/usr/src/sys/boot/i386/cdboot/cdboot $BOOTDIR
loader.rc is the file that the loader reads
and interprets. For m0n0wall, it is used to disable ATA DMA (to increase
compatibility with odd hardware, especially since CF/HD performance
isn't very important in m0n0wall) and load the kernel and the MFS root
file system.
Create the file $BOOTDIR/loader.rc with the
following contents:
set hw.ata.atapi_dma="0"
set hw.ata.ata_dma="0"
load /kernel
load -t mfs_root /mfsroot
boot
If you're building for a platform that only has a serial console, add the flag "-h" (without the quotes) to the "boot" command on the last line.