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From 30d3de4c61c297e12662df1fdb89af335947e59d Mon Sep 17 00:00:00 2001
From: Jan Beulich <jbeulich@suse.com>
Date: Wed, 27 Jul 2022 09:31:31 +0200
Subject: [PATCH 29/67] x86: also suppress use of MMX insns
Passing -mno-sse alone is not enough: The compiler may still find
(questionable) reasons to use MMX insns. In particular with gcc12 use
of MOVD+PUNPCKLDQ+MOVQ was observed in an apparent attempt to auto-
vectorize the storing of two adjacent zeroes, 32 bits each.
Reported-by: ChrisD <chris@dalessio.org>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: 6fe2e39a0243bddba60f83b77b972a5922d25eb8
master date: 2022-07-20 15:48:49 +0200
---
xen/arch/x86/arch.mk | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/xen/arch/x86/arch.mk b/xen/arch/x86/arch.mk
index 456e5d5c1ad7..c4337a1a118c 100644
--- a/xen/arch/x86/arch.mk
+++ b/xen/arch/x86/arch.mk
@@ -37,9 +37,9 @@ $(call as-option-add,CFLAGS,CC,\
CFLAGS += -mno-red-zone -fpic
-# Xen doesn't use SSE interally. If the compiler supports it, also skip the
-# SSE setup for variadic function calls.
-CFLAGS += -mno-sse $(call cc-option,$(CC),-mskip-rax-setup)
+# Xen doesn't use MMX or SSE interally. If the compiler supports it, also skip
+# the SSE setup for variadic function calls.
+CFLAGS += -mno-mmx -mno-sse $(call cc-option,$(CC),-mskip-rax-setup)
# Compile with thunk-extern, indirect-branch-register if avaiable.
CFLAGS-$(CONFIG_INDIRECT_THUNK) += -mindirect-branch=thunk-extern
--
2.37.3
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