User`s manual

PBOOT - Bootstrap Operating System

3-175

Once the boot partition is located by using the boot record, the

debugger will typically:

1. Read into memory the second 512-byte block of the load

image.

2. Determine the load image length, which runs to, but does not

include, the Reserved2 space.

3. Allocate a buffer in system RAM for the load image transfer

(no fixed location).

4. Transfer the remaining portion of the load image into system

RAM from the boot device (the Reserved2 space is not

loaded).

After the load image has been loaded, the debugger transfers

control to the entry point of the loaded code. The state of the

machine at this point is as follows:

❏ Interrupts are masked (i.e., MPU.MSR.EE bit is set a 0).

❏ System I/O addresses are in the contiguous mode.

❏ The system is Big-Endian mode.

❏ The instruction cache is enabled (L1 only).

❏ MPU.GPR3 is set to the starting address of the residual data.

❏ MPU.GPR4 is set to the starting address of the load image.

❏ MPU.GPR5 is set to a zero.

Examples

Example 1: This example demonstrates a boot and halt scenario.

The boot device is an CDROM device, as observed by the IOI

command output.

Note that in this example it was necessary to delimit the remaining

arguments to enable the H option. This delimiting of arguments

specifies to use the defaults for the corresponding argument.