FENCE

Fence

FENCE pred, succ

Orders device I/O and memory accesses.

Details

FENCE orders device I/O and memory accesses as viewed by other RISC-V harts and external devices. The predecessor and successor sets of operations are specified by the pred and succ fields. FENCE with all fields zero is a full memory fence.

Pseudocode Operation

MemoryBarrier(pred, succ);

Example

FENCE rw, rw

Encoding

Binary Layout
fm
31:28
pred
27:24
succ
23:20
rs1
19:15
000
14:12
rd
11:7
0001111
6:0
 
Format I-Type
Opcode 0x0F
Extension RV32I

Operands

  • pred
    Predecessor Set
  • succ
    Successor Set