linux-kernel - [PATCH] MIPS: Loongson2ef: Disable Loongson MMI instructions

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Message-Id: <20200923103312.55507-1-jiaxun.yang@flygoat.com>
Date:   Wed, 23 Sep 2020 18:33:12 +0800
From:   Jiaxun Yang <jiaxun.yang@...goat.com>
To:     linux-mips@...r.kernel.org
Cc:     Jiaxun Yang <jiaxun.yang@...goat.com>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        stable@...r.kernel.org, Paul Burton <paulburton@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] MIPS: Loongson2ef: Disable Loongson MMI instructions

It was missed when I was forking Loongson2ef from Loongson64 but
should be applied to Loongson2ef as march=loongson2f
will also enable Loongson MMI in GCC-9+.

Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
Fixes: 71e2f4dd5a65 ("MIPS: Fork loongson2ef from loongson64")
Reported-by: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc: stable@...r.kernel.org # v5.8+
---
 arch/mips/loongson2ef/Platform | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/mips/loongson2ef/Platform b/arch/mips/loongson2ef/Platform
index 4ab55f1123a0..ae023b9a1c51 100644
--- a/arch/mips/loongson2ef/Platform
+++ b/arch/mips/loongson2ef/Platform
@@ -44,6 +44,10 @@ ifdef CONFIG_CPU_LOONGSON2F_WORKAROUNDS
   endif
 endif
 
+# Some -march= flags enable MMI instructions, and GCC complains about that
+# support being enabled alongside -msoft-float. Thus explicitly disable MMI.
+cflags-y += $(call cc-option,-mno-loongson-mmi)
+
 #
 # Loongson Machines' Support
 #
-- 
2.28.0