xv6

commit 3994dade649dba764fdab1b8660ef609ab373fc9
parent c000f716d78d41d94e58a08c7cb57afef65d6d6f
Author: Brian Swetland <swetland@frotz.net>
Date:   Sat, 28 Dec 2013 14:04:46 -0800

uart: provide earlyinit to allow cprintf to serial very early on

Diffstat:
M
include/defs.h
 | 
1
+
M
kernel/main.c
 | 
1
+
M
kernel/uart.c
 | 
17
++++++++++++-----

3 files changed, 14 insertions(+), 5 deletions(-)
diff --git a/include/defs.h b/include/defs.h
@@ -156,6 +156,7 @@ void            tvinit(void);
 extern struct spinlock tickslock;
 
 // uart.c
+void		uartearlyinit(void);
 void            uartinit(void);
 void            uartintr(void);
 void            uartputc(int);
diff --git a/kernel/main.c b/kernel/main.c
@@ -17,6 +17,7 @@ extern char end[]; // first address after kernel loaded from ELF file
 int
 main(void)
 {
+  uartearlyinit();
   kinit1(end, P2V(4*1024*1024)); // phys page allocator
   kvmalloc();      // kernel page table
   mpinit();        // collect info about this machine
diff --git a/kernel/uart.c b/kernel/uart.c
@@ -16,7 +16,7 @@
 static int uart;    // is there a uart?
 
 void
-uartinit(void)
+uartearlyinit(void)
 {
   char *p;
 
@@ -36,16 +36,23 @@ uartinit(void)
     return;
   uart = 1;
 
+  // Announce that we're here.
+  for(p="xv6...\n"; *p; p++)
+    uartputc(*p);
+}
+
+void
+uartinit(void)
+{
+  if (!uart)
+    return;
+
   // Acknowledge pre-existing interrupt conditions;
   // enable interrupts.
   inb(COM1+2);
   inb(COM1+0);
   picenable(IRQ_COM1);
   ioapicenable(IRQ_COM1, 0);
-  
-  // Announce that we're here.
-  for(p="xv6...\n"; *p; p++)
-    uartputc(*p);
 }
 
 void