Prepare some space for early transfer

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

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();