Artesyn COMX-P40x0 ENP2 Installation and Use (January 2015) - Manual (Page 130)

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COMX-P40x0 ENP2 Installation and Use (6806800R95C) 130
Common device environment variables in U-Boot include the following:
 uart# and consoledev
 ethact and netdev
7.23.1 RAMboot
The COMX-P40x0 ENP2 has a U-Boot variable called "ramboot".
setenv bootargs root=/dev/ram rw console=$consoledev,$baudrate
$hwbootargs $othbootargs;tftp $ramdiskaddr $ramdiskfile;tftp
$loadaddr $bootfile;tftp $fdtaddr $fdtfile;bootm $loadaddr
$ramdiskaddr $fdtaddr
"ramboot" will first load RAMDISK, Linux kernel and DTB into RAM through network by TFTP
then boot.
The following are the critical environment variables for "ramboot":
0 - ttyS0
1 - ttyS1
2 - ttyS2
3 - ttyS3
ethact - Active ethernet port
ramdiskfile - RAMDISK file name on TFTP server
bootfile - Linux kernel file name on TFTP server
fdtfile - DTB file name on TFTP server