User`s manual

PBOOT - Bootstrap Operating System
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The 32-bit start RBA is zero-based. The 32-bit count RBA value is
one-based and indicates the number of 512-byte blocks. The count
is always specified in 512-byte blocks, even if the physical sectoring
of the target device is not 512-byte sectors.
The devices that are not required to contain a boot record (i.e.,
partition table) are treated as if they have a single partition.
Basically, the entire media contents is the data within the partition.
Figure 3-3 identifies the layout of the $41 type partition and the
process of loading the image. The PC Compatibility Block in the
boot partition may contain x86-type program. When executed on
an x86 machine, this program displays a message indicating that
this partition is not applicable to the current system environment.
The second relative block in the boot partition contains the Entry
Point Offset, Load Image Length, Flag Field, OS_ID field, ASCII
Partition Name field, and the Reserved1 area. The 32-bit value
Entry Point Offset (little endian byte ordering) is the offset (into the
image) of the entry point of the PowerPC Reference Platform boot
program. The Entry Point Offset is used to allocate the Reserved1
space. The Reserved1 area from offset 554 to Entry Point - 1 is
reserved for implementation specific data and future expansion.
The 32-bit value Load Image Length (little endian byte ordering) is
the length, in bytes, of the load image. The Load Image Length
specifies the size of the data physically copied into the system RAM
by the debugger. Note, that the debugger can load the boot
program image anywhere into system RAM, the boot program is
responsible for positioning.
partition begin
boot ind head sector cyl
partition end
sys ind head sector cyl
beginning sector
32-bit start RBA (zero-based) (LE)
number of sectors
32-bit RBA count (one-based) (LE)
Figure 3-2. PowerPC Reference Platform Partition Table Entry