From e2272caf4e8f6429a190b7ff95741149f069b6f2 Mon Sep 17 00:00:00 2001
From: Baptiste Wicht <baptiste.wicht@gmail.com>
Date: Sun, 31 Jul 2016 13:14:13 +0200
Subject: [PATCH] Prepare some space for early transfer

---
 kernel/include/early_memory.hpp | 21 +++++++++++++++++++++
 kernel/src/boot/boot_32.cpp     |  4 ++++
 2 files changed, 25 insertions(+)
 create mode 100644 kernel/include/early_memory.hpp

diff --git a/kernel/include/early_memory.hpp b/kernel/include/early_memory.hpp
new file mode 100644
index 00000000..a2708c5c
--- /dev/null
+++ b/kernel/include/early_memory.hpp
@@ -0,0 +1,21 @@
+//=======================================================================
+// Copyright Baptiste Wicht 2013-2016.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+//  http://www.boost.org/LICENSE_1_0.txt)
+//=======================================================================
+
+/*
+ * This header contains addresses where the init stage of the kernel writes information for the later stage
+ */
+
+#ifndef EARLY_MEMORY_H
+#define EARLY_MEMORY_H
+
+// The number of MiB used by the kernel
+constexpr const uint32_t kernel_mib = 0x90000; //4 bytes (32 bits)
+
+// The address of the kernel
+constexpr const uint32_t kernel_address = 0x100000;  //1Mib aligned size (kernel_mib)
+
+#endif
diff --git a/kernel/src/boot/boot_32.cpp b/kernel/src/boot/boot_32.cpp
index b0f09d69..9f19c5ab 100644
--- a/kernel/src/boot/boot_32.cpp
+++ b/kernel/src/boot/boot_32.cpp
@@ -11,6 +11,7 @@
 #include "kernel.hpp"
 #include "paging.hpp"
 #include "early_logging.hpp"
+#include "early_memory.hpp"
 
 namespace {
 
@@ -136,6 +137,9 @@ void pm_main(){
     //Setup paging
     setup_paging();
 
+    // TODO This will need to be computed from the init loader
+    *reinterpret_cast<uint32_t*>(kernel_mib) = 1;
+
     //Enable long mode by setting the EFER.LME flag
     enable_long_mode();