From 8d1e5ffe355b0e0bbb60fa88d306304a1746bc8c Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Sun, 7 Jul 2024 21:56:41 -0400
Subject: kernel/amd64: Add serial debug logging

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/arch/amd64/amd64/machdep.c | 14 ++++++++++++++
 sys/arch/amd64/conf/GENERIC    |  1 +
 sys/include/sys/syslog.h       |  2 ++
 sys/kern/init_main.c           |  3 +++
 sys/kern/kern_syslog.c         |  9 +++++++++
 5 files changed, 29 insertions(+)

diff --git a/sys/arch/amd64/amd64/machdep.c b/sys/arch/amd64/amd64/machdep.c
index b047dd8..03b10f0 100644
--- a/sys/arch/amd64/amd64/machdep.c
+++ b/sys/arch/amd64/amd64/machdep.c
@@ -28,6 +28,7 @@
  */
 
 #include <sys/types.h>
+#include <sys/syslog.h>
 #include <machine/cpu.h>
 #include <machine/gdt.h>
 #include <machine/tss.h>
@@ -36,6 +37,7 @@
 #include <machine/asm.h>
 #include <machine/cpuid.h>
 #include <machine/lapic.h>
+#include <machine/uart.h>
 
 #if defined(__SPECTRE_IBRS)
 #define SPECTRE_IBRS  __SPECTRE_IBRS
@@ -90,6 +92,18 @@ try_mitigate_spectre(void)
     ibrs_enable();
 }
 
+void
+serial_init(void)
+{
+    uart_init();
+}
+
+void
+serial_putc(char c)
+{
+   uart_write(c);
+}
+
 /*
  * Get the descriptor for the currently
  * running processor.
diff --git a/sys/arch/amd64/conf/GENERIC b/sys/arch/amd64/conf/GENERIC
index a7bbc81..19c9a62 100644
--- a/sys/arch/amd64/conf/GENERIC
+++ b/sys/arch/amd64/conf/GENERIC
@@ -1,5 +1,6 @@
 // Kernel options
 option SPECTRE_IBRS no
+option SERIAL_DEBUG yes
 
 // Kernel constants
 setval SCHED_NQUEUE 4
diff --git a/sys/include/sys/syslog.h b/sys/include/sys/syslog.h
index 9a044b9..889bf37 100644
--- a/sys/include/sys/syslog.h
+++ b/sys/include/sys/syslog.h
@@ -37,6 +37,8 @@
 #define OMIT_TIMESTAMP "\x01"
 
 void kprintf(const char *fmt, ...);
+void serial_init(void);
+void serial_putc(char c);
 void vkprintf(const char *fmt, va_list *ap);
 
 #endif  /* !_KERNEL */
diff --git a/sys/kern/init_main.c b/sys/kern/init_main.c
index 02e8705..71763b3 100644
--- a/sys/kern/init_main.c
+++ b/sys/kern/init_main.c
@@ -60,6 +60,9 @@ start_init(void)
 int
 main(void)
 {
+    /* Setup serial driver */
+    serial_init();
+
     /* Startup the console */
     cons_init();
     kprintf("Starting Hyra/%s v%s: %s\n", HYRA_ARCH, HYRA_VERSION,
diff --git a/sys/kern/kern_syslog.c b/sys/kern/kern_syslog.c
index 6962a69..7f66db0 100644
--- a/sys/kern/kern_syslog.c
+++ b/sys/kern/kern_syslog.c
@@ -34,6 +34,12 @@
 #include <stdarg.h>
 #include <string.h>
 
+#if defined(__SERIAL_DEBUG)
+#define SERIAL_DEBUG __SERIAL_DEBUG
+#else
+#define SERIAL_DEBUG 0
+#endif
+
 /* Global logger lock */
 static struct spinlock lock = {0};
 
@@ -44,6 +50,9 @@ syslog_write(const char *s, size_t len)
 
     while (len--) {
         cons_putch(&g_root_scr, *p);
+        if (SERIAL_DEBUG) {
+            serial_putc(*p);
+        }
         ++p;
     }
 }
-- 
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