xnu-1504.15.3.tar.gz

[apple/xnu.git] / pexpert / i386 / pe_kprintf.c

diff --git a/pexpert/i386/pe_kprintf.c b/pexpert/i386/pe_kprintf.c
index 84855f63ec347780278cf2eba30da6a5090a83ce..b25bbcf28ca313ce46f9072a57a7573fdce8f5fd 100644 (file)
--- a/pexpert/i386/pe_kprintf.c
+++ b/pexpert/i386/pe_kprintf.c
@@ -39,7 +39,14 @@
 /* Globals */
 void (*PE_kputc)(char c);
 
+#if DEBUG
+/* DEBUG kernel starts with true serial, but
+ * may later disable or switch to video
+ * console */
+unsigned int disable_serial_output = FALSE;
+#else
 unsigned int disable_serial_output = TRUE;
+#endif
 
 decl_simple_lock_data(static, kprintf_lock)
 
@@ -51,19 +58,30 @@ void PE_init_kprintf(boolean_t vm_initialized)
                panic("Platform Expert not initialized");
 
        if (!vm_initialized) {
+               unsigned int new_disable_serial_output = TRUE;
+
                simple_lock_init(&kprintf_lock, 0);
 
                if (PE_parse_boot_argn("debug", &boot_arg, sizeof (boot_arg)))
                        if (boot_arg & DB_KPRT)
-                               disable_serial_output = FALSE;
+                               new_disable_serial_output = FALSE;
 
-               if (!disable_serial_output && serial_init())
+               /* If we are newly enabling serial, make sure we only call serial_init()
+                * if our previous state was not enabled */
+               if (!new_disable_serial_output && (!disable_serial_output || serial_init()))
                        PE_kputc = serial_putc;
                else
                        PE_kputc = cnputc;
+
+               disable_serial_output = new_disable_serial_output;
        }
 }
 
+#if CONFIG_NO_KPRINTF_STRINGS
+/* Prevent CPP from breaking the definition below */
+#undef kprintf
+#endif
+
 #ifdef MP_DEBUG
 static void _kprintf(const char *format, ...)
 {
@@ -86,6 +104,15 @@ void kprintf(const char *fmt, ...)
 
        if (!disable_serial_output) {
 
+               /* If PE_kputc has not yet been initialized, don't
+                * take any locks, just dump to serial */
+               if (!PE_kputc) {
+                       va_start(listp, fmt);
+                       _doprnt(fmt, &listp, serial_putc, 16);
+                       va_end(listp);
+                       return;
+               }
+
                /*
                 * Spin to get kprintf lock but re-enable interrupts while
                 * failing.