From c73fc79260a99d79f3c93686d6b0f6906a286f7e Mon Sep 17 00:00:00 2001
From: Baptiste Wicht <baptiste.wicht@gmail.com>
Date: Mon, 10 Mar 2014 19:02:50 +0100
Subject: [PATCH] Prepare some basic early logging support

---
 kernel/include/early_logging.hpp | 22 ++++++++++++++++++++++
 kernel/src/boot/boot_16.cpp      | 27 +++++++++++++++++++++------
 2 files changed, 43 insertions(+), 6 deletions(-)
 create mode 100644 kernel/include/early_logging.hpp

diff --git a/kernel/include/early_logging.hpp b/kernel/include/early_logging.hpp
new file mode 100644
index 00000000..757a7ebf
--- /dev/null
+++ b/kernel/include/early_logging.hpp
@@ -0,0 +1,22 @@
+//=======================================================================
+// Copyright Baptiste Wicht 2013-2014.
+// 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)
+//=======================================================================
+
+#include <types.hpp>
+
+#ifndef EARLY_LOGGING_HPP
+#define EARLY_LOGGING_HPP
+
+namespace early {
+
+constexpr const uint32_t MAX_EARLY_LOGGING = 128;
+
+extern uint32_t early_logs_count;
+extern uint32_t early_logs[MAX_EARLY_LOGGING];
+
+} //end of namespace early
+
+#endif
\ No newline at end of file
diff --git a/kernel/src/boot/boot_16.cpp b/kernel/src/boot/boot_16.cpp
index 93dfa61e..a21aef6e 100644
--- a/kernel/src/boot/boot_16.cpp
+++ b/kernel/src/boot/boot_16.cpp
@@ -13,10 +13,14 @@
 #include "gdt.hpp"
 #include "e820.hpp" //Just for the address of the e820 map
 #include "vesa.hpp"
+#include "early_logging.hpp"
 
 //The Task State Segment
 gdt::task_state_segment_t gdt::tss;
 
+uint32_t early::early_logs_count = 0;
+uint32_t early::early_logs[early::MAX_EARLY_LOGGING];
+
 e820::bios_e820_entry e820::bios_e820_entries[e820::MAX_E820_ENTRIES];
 int16_t e820::bios_e820_entry_count = 0;
 
@@ -26,17 +30,25 @@ bool vesa::vesa_enabled = false;
 
 namespace {
 
+/* Early Logging  */
+
+void early_log(const char* s){
+    early::early_logs[early::early_logs_count++] = reinterpret_cast<uint32_t>(s);
+}
+
+/* VESA */
+
 constexpr const uint16_t DEFAULT_WIDTH = 1280;
 constexpr const uint16_t DEFAULT_HEIGHT = 1024;
 constexpr const uint16_t DEFAULT_BPP = 32;
 
 void out_byte(uint8_t value, uint16_t port){
-    __asm__ __volatile__("out %1, %0" : : "a" (value), "dN" (port));
+    asm volatile("out %1, %0" : : "a" (value), "dN" (port));
 }
 
 uint8_t in_byte(uint16_t port){
     uint8_t value;
-    __asm__ __volatile__("in %0,%1" : "=a" (value) : "dN" (port));
+    asm volatile("in %0,%1" : "=a" (value) : "dN" (port));
     return value;
 }
 
@@ -74,9 +86,12 @@ int detect_memory_e820(){
             : "a"(0xE820), "b"(contID), "c"(24), "d"(0x534D4150), "D"(&buf));
 
         if (signature != 0x534D4150){
+            early_log("e820 failed");
             return -1;
         }
 
+        early_log("Found e820 entry");
+
         if (bytes > 20 && (smap->acpi & 0x0001) == 0){
             // ignore this entry
         } else {
@@ -199,7 +214,7 @@ void setup_vesa(){
 }
 
 void disable_interrupts(){
-    __asm__ __volatile__ ("cli");
+    asm volatile ("cli");
 }
 
 void enable_a20_gate(){
@@ -400,15 +415,15 @@ void  __attribute__ ((noreturn)) rm_main(){
     //Make sure segments are clean
     reset_segments();
 
+    //Enable VESA
+    setup_vesa();
+
     //Analyze memory
     detect_memory();
 
     //Make sure a20 gate is enabled
     enable_a20_gate();
 
-    //Enable VESA
-    setup_vesa();
-
     //Disable interrupts
     disable_interrupts();