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[PATCH 1/2] target/sparc: Set TCG_GUEST_DEFAULT_MO
From: |
Richard Henderson |
Subject: |
[PATCH 1/2] target/sparc: Set TCG_GUEST_DEFAULT_MO |
Date: |
Tue, 20 Jun 2023 18:40:39 +0200 |
Always use TSO, per the Oracle 2015 manual.
This is slightly less restrictive than the TCG_MO_ALL default,
and happens to match the i386 model, which will eliminate a few
extra barriers on that host.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
target/sparc/cpu.h | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/target/sparc/cpu.h b/target/sparc/cpu.h
index 3d090e8278..49c53f5c40 100644
--- a/target/sparc/cpu.h
+++ b/target/sparc/cpu.h
@@ -6,6 +6,29 @@
#include "exec/cpu-defs.h"
#include "qemu/cpu-float.h"
+/*
+ * From Oracle SPARC Architecture 2015:
+ *
+ * Compatibility notes: The PSO memory model described in SPARC V8 and
+ * SPARC V9 compatibility architecture specifications was never implemented
+ * in a SPARC V9 implementation and is not included in the Oracle SPARC
+ * Architecture specification.
+ *
+ * The RMO memory model described in the SPARC V9 specification was
+ * implemented in some non-Sun SPARC V9 implementations, but is not
+ * directly supported in Oracle SPARC Architecture 2015 implementations.
+ *
+ * Therefore always use TSO in QEMU.
+ *
+ * D.5 Specification of Partial Store Order (PSO)
+ * ... [loads] are followed by an implied MEMBAR #LoadLoad | #LoadStore.
+ *
+ * D.6 Specification of Total Store Order (TSO)
+ * ... PSO with the additional requirement that all [stores] are followed
+ * by an implied MEMBAR #StoreStore.
+ */
+#define TCG_GUEST_DEFAULT_MO (TCG_MO_LD_LD | TCG_MO_LD_ST | TCG_MO_ST_ST)
+
#if !defined(TARGET_SPARC64)
#define TARGET_DPREGS 16
#else
--
2.34.1