SH7750_08 Datasheet, PDF (180/1162 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

Section 3 Memory Management Unit (MMU)
3.6 MMU Exceptions
There are seven MMU exceptions: the instruction TLB multiple hit exception, instruction TLB
miss exception, instruction TLB protection violation exception, data TLB multiple hit exception,
data TLB miss exception, data TLB protection violation exception, and initial page write
exception. Refer to figures 3.10 and 3.11 for the conditions under which each of these exceptions
occurs.
3.6.1 Instruction TLB Multiple Hit Exception
An instruction TLB multiple hit exception occurs when more than one ITLB entry matches the
virtual address to which an instruction access has been made. If multiple hits occur when the
UTLB is searched by hardware in hardware ITLB miss handling, a data TLB multiple hit
exception will result.
When an instruction TLB multiple hit exception occurs a reset is executed, and cache coherency is
not guaranteed.
Hardware Processing: In the event of an instruction TLB multiple hit exception, hardware carries
out the following processing:
1. Sets the virtual address at which the exception occurred in TEA.
2. Sets exception code H'140 in EXPEVT.
3. Branches to the reset handling routine (H'A000 0000).
Software Processing (Reset Routine): The ITLB entries which caused the multiple hit exception
are checked in the reset handling routine. This exception is intended for use in program
debugging, and should not normally be generated.
3.6.2 Instruction TLB Miss Exception
An instruction TLB miss exception occurs when address translation information for the virtual
address to which an instruction access is made is not found in the UTLB entries by the hardware
ITLB miss handling procedure. The instruction TLB miss exception processing carried out by
hardware and software is shown below. This is the same as the processing for a data TLB miss
exception.
Rev.7.00 Oct. 10, 2008 Page 96 of 1074
REJ09B0366-0700