From be430b9648698640c0f14585d9085ed570b32878 Mon Sep 17 00:00:00 2001
From: Reto Buerki <reet@codelabs.ch>
Date: Wed, 11 Feb 2015 15:40:51 +0100
Subject: [PATCH] hw_x86_64: Enable Physical Address Extension (PAE)

This is a prerequisite for IA-32e mode.
---
 repos/base-hw/src/core/spec/x86_64/kernel/crt0.s | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/repos/base-hw/src/core/spec/x86_64/kernel/crt0.s b/repos/base-hw/src/core/spec/x86_64/kernel/crt0.s
index 2e5e5483a..79c322049 100644
--- a/repos/base-hw/src/core/spec/x86_64/kernel/crt0.s
+++ b/repos/base-hw/src/core/spec/x86_64/kernel/crt0.s
@@ -27,6 +27,11 @@
 	.global _start
 	_start:
 
+	/* Enable PAE (prerequisite for IA-32e mode) */
+	movl %cr4, %eax
+	btsl $5, %eax
+	movl %eax, %cr4
+
 	/*
 	 * Install initial temporary environment that is replaced later by the
 	 * environment that init_main_thread creates.