Hi Maxim,
BB-xM doesn't have NAND flash, it can boot from SD card only. Thus,
basically you have two options:
1. Change default boot command in U-Boot sources which is a little bit
annoying (file "include/configs/omap3_beagle.h" string "#define
CONFIG_EXTRA_ENV_SETTINGS");
2. Setup a boot script for U-Boot (usually it's a file boot.scr). This
file has special format (I guess some kind of CRC checking) so in
order to produce this file you should do the next steps:
a) Make a file with your new U-Boot commands:
cat << EOF > my_boot_cmd
mmc init
reset
EOF
(Just kidding, don't use "reset", use you commands instead :) ).
b) Use next command (make sure you have "uboot-mkimage" installed, on
ubuntu "apt-get install uboot-mkimage"):
mkimage -A arm -O linux -T script -C none -a 0 -e 0 -n
"Beagleboard-xM boot script" -d my_boot_cmd boot.scr
c) Copy boot.scr to the FAT partition on your SD card (where you have
MLO, u-boot.bin, uImage etc.).
What about "mem=99M@0x80000000 mem=128M@0x88000000" - these parameters
are just a part of your kernel boot command-line parameters. So
probably using of "mem=" argument depends on your kernel
configuration.
Cheers,
Max.