From 68f43121fbf0df8cd231eaf2b9ba0f2db360859c Mon Sep 17 00:00:00 2001
From: Stenzek <stenzek@gmail.com>
Date: Fri, 12 Jan 2024 13:58:17 +1000
Subject: [PATCH] MTGS: Explicitly set FP control register on startup

Linux appears? to inherit the value of MXCSR from the creating thread,
and that breaks parts of the software renderer.
---
 pcsx2/MTGS.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/pcsx2/MTGS.cpp b/pcsx2/MTGS.cpp
index 7128a7ed54..d127e1046a 100644
--- a/pcsx2/MTGS.cpp
+++ b/pcsx2/MTGS.cpp
@@ -9,6 +9,7 @@
 #include "IconsFontAwesome5.h"
 #include "VMManager.h"
 
+#include "common/FPControl.h"
 #include "common/ScopedGuard.h"
 #include "common/StringUtil.h"
 #include "common/WrappedMemCopy.h"
@@ -144,6 +145,10 @@ void MTGS::ThreadEntryPoint()
 {
 	Threading::SetNameOfCurrentThread("GS");
 
+	// Explicitly set rounding mode to default (nearest, FTZ off).
+	// Otherwise it appears to get inherited from the EE thread on Linux.
+	FPControlRegister::SetCurrent(FPControlRegister::GetDefault());
+
 	for (;;)
 	{
 		// wait until we're actually asked to initialize (and config has been loaded, etc)