User`s manual

GEVBOOT - Global Environment Variable Boot
3-65
3
Styles of Booting
The older Motorola mode of mass storage device booting was also
preserved for backward compatibility. However, priority is given
to the new style of booting (i.e., NVRAM boot list).
The older product supports booting from the network. However, it
does not support it as per the PRP specification. The PRP
specification specifies the boot image from a mass storage device to
be the same when booting from a network interface. The older
support treats the network boot image as a raw binary, no format
understood. The new support understands the PRP boot image.
The PRP boot image does have a defined format. The network boot
image may be loaded any where in memory, as per the PRP
specification.
Support has been added to the product to enable the PRP style of
networking booting. The former style is also preserved for
backward compatibility. However, priority is given to the new style
of network booting. This enablement is in the form of a new ENV
parameter.
Both styles of network booting are supported. The new style of
networking booting (i.e., PRP) is controlled by an ENV
configuration parameter. The default state of the ENV
configuration parameter is set to enable the PRP style of network
booting. Disabling this parameter will effectively default the
network boot process to the past mode of network booting (i.e., no
file format understood). This support is identified by the following
ENV parameter:
Network PReP-Boot Mode Enable [Y/N], defaults to 'Y'
PPC1Bug revision 1.8 added a new global environment variable
(GEV) "fw-boot-path" boot to the global firmware boot process. The
boot priority, for both mass storage device boot and network
interface boot, is given first to the "fw-boot-path" GEV.
To support this, a new boot process has been added. This boot
process is labeled "NVRAM Boot List" boot.This new boot process
is identified by the ENV command parameters of: