From ace61c54d638a74d6e544c16e2c5f9d6b5e5fd5f Mon Sep 17 00:00:00 2001
From: Adrian-Ken Rueegsegger <ken@codelabs.ch>
Date: Thu, 12 Mar 2015 17:36:56 +0100
Subject: [PATCH] hw_x86_64: Zero-fill BSS segment in x86_64 crt0.s

Make sure all content of the BSS segment is initialized to zero.
---
 repos/base-hw/src/core/spec/x86_64/kernel/crt0.s | 10 ++++++++++
 1 file changed, 10 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 a61f5635c..d8069a967 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
@@ -29,6 +29,16 @@
 	.global _start
 	_start:
 
+	/**
+	 * zero-fill BSS segment
+	 */
+	leal _bss_start, %edi
+	leal _bss_end, %ecx
+	sub %edi, %ecx
+	shr $2, %ecx
+	xor %eax, %eax
+	rep stosl
+
 	/* Enable PAE (prerequisite for IA-32e mode) and OSFXSR */
 	movl %cr4, %eax
 	btsl $5, %eax