Kernel: Add serial_debug cmdline parameter

serial_debug will output all the kprintf and dbgprintf data to COM1 at
8-N-1 57600 baud. this is particularly useful for debugging the boot
process on live hardware.

Note: it must be the first parameter in the boot cmdline.

1 files changed, 58 insertions, 5 deletions

diff --git a/Kernel/kprintf.cpp b/Kernel/kprintf.cpp
index 468ce55ab7..0cf012ed40 100644
--- a/Kernel/kprintf.cpp
+++ b/Kernel/kprintf.cpp
@@ -6,6 +6,18 @@
 #include <Kernel/kstdio.h>
 #include <LibC/stdarg.h>
 
+static bool serial_debug;
+
+void set_serial_debug(bool on_or_off)
+{
+    serial_debug = on_or_off;
+}
+
+int get_serial_debug()
+{
+    return serial_debug;
+}
+
 static void color_on()
 {
     IO::out8(0xe9, 0x1b);
@@ -22,8 +34,42 @@ static void color_off()
     IO::out8(0xe9, '0');
     IO::out8(0xe9, 'm');
 }
+
+static void serial_putch(char ch)
+{
+    static bool serial_ready = false;
+    static bool was_cr = false;
+
+    if (!serial_ready) {
+        IO::out8(0x3F8 + 1, 0x00);
+        IO::out8(0x3F8 + 3, 0x80);
+        IO::out8(0x3F8 + 0, 0x02);
+        IO::out8(0x3F8 + 1, 0x00);
+        IO::out8(0x3F8 + 3, 0x03);
+        IO::out8(0x3F8 + 2, 0xC7);
+        IO::out8(0x3F8 + 4, 0x0B);
+
+        serial_ready = true;
+    }
+
+    while ((IO::in8(0x3F8 + 5) & 0x20) == 0)
+        ;
+
+    if (ch == '\n' && !was_cr)
+        IO::out8(0x3F8, '\r');
+
+    IO::out8(0x3F8, ch);
+
+    if (ch == '\r')
+        was_cr = true;
+    else
+        was_cr = false;
+}
+
 static void console_putch(char*&, char ch)
 {
+    if (serial_debug)
+        serial_putch(ch);
     if (!current) {
         IO::out8(0xe9, ch);
         return;
@@ -57,16 +103,23 @@ int ksprintf(char* buffer, const char* fmt, ...)
     return ret;
 }
 
-extern "C" int dbgputstr(const char* characters, int length)
+static void debugger_out(char ch)
 {
-    for (int i = 0; i < length; ++i)
-        IO::out8(0xe9, characters[i]);
-    return 0;
+    if (serial_debug)
+        serial_putch(ch);
+    IO::out8(0xe9, ch);
 }
 
 static void debugger_putch(char*&, char ch)
 {
-    IO::out8(0xe9, ch);
+    debugger_out(ch);
+}
+
+extern "C" int dbgputstr(const char* characters, int length)
+{
+    for (int i = 0; i < length; ++i)
+        debugger_out(characters[i]);
+    return 0;
 }
 
 extern "C" int dbgprintf(const char* fmt, ...)