Since Linux v4.15, smp_mb(), smp_wmb(), and smp_rmb() don't suffice
for ordering them.
Update the text accordingly and add a footnote.
Signed-off-by: Akira Yokosawa <akiyks@xxxxxxxxx>
---
memorder/memorder.tex | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/memorder/memorder.tex b/memorder/memorder.tex
index 6b9c3268e589..da56a6999c3f 100644
--- a/memorder/memorder.tex
+++ b/memorder/memorder.tex
@@ -6075,8 +6075,10 @@ that same location, you are on your own.
Some SSE instructions are weakly ordered (\co{clflush}
and non-temporal move instructions~\cite{IntelXeonV2b-96a}).
Code that uses these non-temporal move instructions
-can also use \co{mfence} for \co{smp_mb()},
-\co{lfence} for \co{smp_rmb()}, and \co{sfence} for \co{smp_wmb()}.
+can use \co{mfence} for \co{mb()},
+\co{lfence} for \co{rmb()}, and \co{sfence} for \co{wmb()}.\footnote{
+ \co{smp_mb()}, \co{smp_rmb()}, and \co{smp_wmb()} don't suffice
+ for ordering non-temporal move instructions since Linux v4.15.}
A few older variants of the x86 CPU have a mode bit that enables out-of-order
stores, and for these CPUs, \co{smp_wmb()} must also be defined to
be \co{lock;addl}.
--
2.25.1
