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Diffstat (limited to 'tcg/README')
| -rw-r--r-- | tcg/README | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/tcg/README b/tcg/README index ce8bebab37..1d48aa963f 100644 --- a/tcg/README +++ b/tcg/README @@ -402,6 +402,23 @@ double-word product T0. The later is returned in two single-word outputs. Similar to mulu2, except the two inputs T1 and T2 are signed. +********* Memory Barrier support + +* mb <$arg> + +Generate a target memory barrier instruction to ensure memory ordering as being +enforced by a corresponding guest memory barrier instruction. The ordering +enforced by the backend may be stricter than the ordering required by the guest. +It cannot be weaker. This opcode takes a constant argument which is required to +generate the appropriate barrier instruction. The backend should take care to +emit the target barrier instruction only when necessary i.e., for SMP guests and +when MTTCG is enabled. + +The guest translators should generate this opcode for all guest instructions +which have ordering side effects. + +Please see docs/atomics.txt for more information on memory barriers. + ********* 64-bit guest on 32-bit host support The following opcodes are internal to TCG. Thus they are to be implemented by |