Artesyn COMX-P4080 Installation and Use (August 2014) - Manual (Page 117)

BSP Operations
COMX-P4080 COM Express Module Installation and Use (6806800L20C) 117
setenv bootargs root=/dev/$usbbdev rw rootdelay=30
console=$consoledev,$baudrate $hwbootargs $othbootargs;usb
start;ext2load usb 0:2 $loadaddr /boot/$bootfile;ext2load usb 0:2
$fdtaddr /boot/$fdtfile;bootm $loadaddr - $fdtaddr
The "usbfatboot" will load Linux kernel and DTB from the FAT partition (1st partition) on USB
stick into RAM and then boot. EXT2 partition (2nd partition) will be mounted on the USB stick
as rootfs.
The "usbext2boot" will load Linux kernel and DTB from the EXT2 partition (2nd partition) on
USB stick into RAM and then boot. Mounting it on the same partition on this USB stick will boot
as rootfs
The following are the critical environment variables for "usbfatboot" and "usbext2bot".
Below are examples of critical environment variables.
Users need to create two partitions on the USB stick. FAT32 is the first partition and the EXT2
is the second partition. Both partitiions contain a directory /boot/ and the directory has kernel
DTB files. EXT2 partition contains the rootfs which can be from rootfs_nfs.tar.gz
7.19.6 MMCFATboot and MMCEXT2boot
COMX-P4080 has a U-Boot variable called "mmcfatboot".
setenv bootargs root=/dev/$mmcbdev rw rootdelay=30
console=$consoledev,$baudrate $hwbootargs
$othbootargs;mmcinfo;fatload mmc 0:1 $loadaddr
/boot/$bootfile;fatload mmc 0:1 $fdtaddr /boot/$fdtfile;bootm
$loadaddr - $fdtaddr
COMX-P4080 also has a U-Boot variable called "mmcext2boot".
bootfile - Linux kernel file name
fdtfile - DTB file name
=> setenv bootfile COMX_P4080_V100R00/uImage
=> setenv fdtfile COMX_P4080_V100R00/comx.dtb