NEC Network Controller uPD98502 - Manual (Page 103)

CHAPTER 2 V R 4120A
Preliminary User’s Manual S15543EJ1V0UM 103
2.4.2.1 Virtual-to-physical address translation
Converting a virtual address to a physical address begins by comparing the virtual address from the processor with
the virtual addresses in the TLB; there is a match when the virtual page number (VPN) of the address is the same as
the VPN field of the entry, and either:
— the Global (G) bit of the TLB entry is set to 1
— the ASID field of the virtual address is the same as the ASID field of the TLB entry.
This match is referred to as a TLB hit. If there is no match, a TLB Mismatch exception is taken by the processor
and software is allowed to refill the TLB from a page table of virtual/physical addresses in memory.
If there is a virtual address match in the TLB, the physical address is output from the TLB and concatenated with
the offset, which represents an address within the page frame space. The offset does not pass through the TLB.
Instead, the low-order bits of the virtual address are output without being translated. For details about the physical
address, see Section 2.4.5.11 Virtual-to-physical address translation.
The next two sections describe the 32-bit and 64-bit mode address translations.