From 750d79dcafc618066c7a9e3ca704c989edc52249 Mon Sep 17 00:00:00 2001
From: Andreas Kling <awesomekling@gmail.com>
Date: Wed, 27 Mar 2019 13:40:00 +0100
Subject: [PATCH] Kernel: Initialize the CPU to allow SSE on startup.

I still need to add support for SSE to the context switching code, but now
at least one process can use it.
---
 Kernel/i386.cpp | 13 +++++++++++++
 Kernel/i386.h   |  1 +
 Kernel/init.cpp |  2 ++
 3 files changed, 16 insertions(+)

diff --git a/Kernel/i386.cpp b/Kernel/i386.cpp
index d049d3afe0..1879ba9206 100644
--- a/Kernel/i386.cpp
+++ b/Kernel/i386.cpp
@@ -493,3 +493,16 @@ void __assertion_failed(const char* msg, const char* file, unsigned line, const
     asm volatile("hlt");
     for (;;);
 }
+
+void sse_init()
+{
+    asm volatile(
+        "mov %cr0, %eax\n"
+        "andl $0xfffffffb, %eax\n"
+        "orl $0x2, %eax\n"
+        "mov %eax, %cr0\n"
+        "mov %cr4, %eax\n"
+        "orl $0x600, %eax\n"
+        "mov %eax, %cr4\n"
+    );
+}
diff --git a/Kernel/i386.h b/Kernel/i386.h
index 9b2b3447d4..fcf70cf7cc 100644
--- a/Kernel/i386.h
+++ b/Kernel/i386.h
@@ -61,6 +61,7 @@ class IRQHandler;
 
 void gdt_init();
 void idt_init();
+void sse_init();
 void register_interrupt_handler(byte number, void (*f)());
 void register_user_callable_interrupt_handler(byte number, void (*f)());
 void register_irq_handler(byte number, IRQHandler&);
diff --git a/Kernel/init.cpp b/Kernel/init.cpp
index 09ae0b49b9..d9f4c77d57 100644
--- a/Kernel/init.cpp
+++ b/Kernel/init.cpp
@@ -140,6 +140,8 @@ VFS* vfs;
 {
     cli();
 
+    sse_init();
+
     kmalloc_init();
     init_ksyms();