Kontron NetBootLoader - Manual (Page 17)

ID 1022-8317, Rev. 2.0
NBL Operation NetBootLoader
Page 9
use of appropriate configuration files, pre-setting of the SCRIPT command, pre-setting of the
SQ (Sequence) command, and pre-programming of bootable images to the NOR and/or NAND
Flashes.
In this case, the boot process is controlled by the contents of the above mentioned entities as
follows:
• With modules that provide NAND Flash capability, the NetBootLoader first searches for
a FAT partition that is marked bootable (only one partition may be so marked)
• If such a partition is found, it then searches for “nbl.cfg” configuration files beginning
with the file “nbl0.cfg”. When a file is found, the NetBootLoader executes it.
• If the file execution does not result in an image being loaded and started or the boot pro-
cess being aborted, the NetBootLoader searches for the next available configuration file,
and, if one is found, it is executed. This continues until either all “nbl.cfg” files have
been executed, the boot process is aborted, or an image is loaded and started.
• In the event a bootable FAT partition is not found or all available “nbl.cfg” files have
been executed without either aborting the boot process or loading and starting an image,
the NetBootLoader searches for any script previously specified by the SCRIPT com-
mand. If found, it is also executed.
• If a script is not found, or if the script execution does not result in an image being loaded
and started or in the boot process being aborted, the NetBootLoader continues with the
processing of image(s) stored in NOR Flash (according to the order defined by the SQ
command if specified, or 0, 1, 2, 3 if not specified). The first valid (CRC check passed)
image found is loaded and started. If a valid image is not found, the boot process is abort-
ed and a command interpreter is made available.
With the introduction of NAND Flash, the boot process may indirectly be influenced via an op-
erating system. After an initial boot up and starting of an operating system, the contents of files
in the NAND Flash may be altered via OS functions, so that a very customized boot process
may be specified without having to use NetBootLoader file editing functions. With the next boot
up, the “new” boot process can then be executed.
2.6.3.2 Alternate Boot Process
For modules which support IPMI and NAND Flash, there is an alternate boot capability (known
as netboot) which can be invoked from a remote location using IPMI commands. This can be
used for situations where the standard boot process fails leaving the module payload inopera-
ble or a non-standard application configuration is required for whatever reason. This is
achieved by setting the boot order via IPMI and then having the MMC reboot the payload.
For example, using the “ipmitool” software the following command line can be invoked to set a
register that is evaluated by the NetBootLoader on the next payload restart:
ipmitool -l 0x00 0x3E 0x20 0x9D 0x00 or 0x01
where 0x00 is for standard boot process and 0x01 for the alternate boot process. This value
must be explicitly set (reset) as it is stored in non-volatile memory.
At reboot start, the NetBootLoader first searches for a FAT partition on the NAND Flash that is
marked bootable. If such a partition is found, it then searches for a configuration file named
“net.cfg”. If found, the NetBootLoader executes it.