PowerPC e500 Core Family Reference Manual, Rev. 1
1-32
Freescale Semiconductor
Core Complex Overview
1.13 Legacy Support of PowerPC Architecture
This section provides an overview of the architectural differences and compatibilities of the e500
core compared with the AIM PowerPC architecture. The two levels of the e500 programming
environment are as follows:
•
User level—This defines the base user-level instruction set, user-level registers, data types,
memory conventions, and the memory and programming models seen by application
programmers.
•
Supervisor level—This defines supervisor-level resources typically required by an
operating system, the memory management model, supervisor level registers, and the
exception model.
In general, the e500 core supports the user-level architecture from the existing AIM architecture.
The following subsections are intended to highlight the main differences. For specific
implementation details refer to the relevant chapter.
1.13.1 Instruction Set Compatibility
The following sections generally describe the user and supervisor instruction sets.
1.13.1.1 User Instruction Set
The e500 core executes legacy user-mode binaries and object files except for the following:
•
The e500 supports vector and scalar single-precision floating-point operations as APUs.
The e500v2 supports scalar double-precision floating-point instructions. These instructions
have different encoding than the AIM definition of the PowerPC architecture. Additionally,
the e500 core uses GPRs for floating-point operations, rather than the FPRs defined by the
UISA. Most porting of floating-point operations can be handled by recompiling.
•
String instructions are not implemented on the e500; therefore, trap emulation must be
provided to ensure backward compatibility.
1.13.1.2 Supervisor Instruction Set
The supervisor mode instruction set defined by the AIM version of the PowerPC architecture is
compatible with the e500 with the following exceptions:
•
The MMU architecture is different, so some TLB manipulation instructions have different
semantics.
•
Instructions that support the BATs and segment registers are not implemented.
Summary of Contents for PowerPC e500 Core
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