From 4dc79c4ee6d59bdef01b1f7f38eb176b3813d209 Mon Sep 17 00:00:00 2001
From: Braiden Vasco <braiden-vasco@users.noreply.github.com>
Date: Sun, 5 Nov 2017 07:32:32 +0000
Subject: [PATCH] Do not allocate in lower memory

---
 arch/config.h | 2 ++
 arch/memory.c | 5 ++++-
 arch/paging.c | 2 --
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/config.h b/arch/config.h
index 2080693..21e1568 100644
--- a/arch/config.h
+++ b/arch/config.h
@@ -1,6 +1,8 @@
 #ifndef KERNELMQ_INCLUDED_CONFIG
 #define KERNELMQ_INCLUDED_CONFIG 1
 
+#define MEM_UPPER_BASE ((unsigned long)(1 * 1024 * 1024 * 1024)) // 1 MB
+
 #define PAGE_DIR_SIZE   1024
 #define PAGE_TABLE_SIZE 1024
 
diff --git a/arch/memory.c b/arch/memory.c
index 1012d1e..e655464 100644
--- a/arch/memory.c
+++ b/arch/memory.c
@@ -14,6 +14,8 @@ void memory_initialize(const struct KernelMQ_Info *const kinfo)
 {
     kmemset(frames, 0, sizeof(frames));
 
+    mark_used(0, MEM_UPPER_BASE - 1);
+
     mark_used(kinfo->kernel_phys_base, kinfo->kernel_phys_limit);
 
     for (unsigned int i = 0; i < kinfo->modules_count; ++i) {
@@ -35,6 +37,7 @@ unsigned long memory_alloc_page()
 {
     for (unsigned int i = 0; i < FRAMES_COUNT; ++i) {
         if (!frames[i]) {
+            frames[i] = 0xFF;
             return i * PAGE_SIZE;
         }
     }
@@ -48,6 +51,6 @@ void mark_used(const unsigned long base, const unsigned long limit)
     const unsigned int end   = limit / PAGE_SIZE;
 
     for (unsigned int i = start; i <= end; ++i) {
-        frames[i] = 1;
+        frames[i] = 0xFF;
     }
 }
diff --git a/arch/paging.c b/arch/paging.c
index 5ba2ad8..acf0a2f 100644
--- a/arch/paging.c
+++ b/arch/paging.c
@@ -4,8 +4,6 @@
 
 #include <kernelmq/stdlib.h>
 
-#define MEM_UPPER_BASE ((unsigned long)(1 * 1024 * 1024 * 1024)) // 1 MB
-
 // i386 paging constants
 #define I386_VM_PRESENT 0x001 // Page is present
 #define I386_VM_WRITE   0x002 // Read/write access allowed