[PATCH 2/2] kvm-unit-tests: make I/O more friendly to existing QEMU hardware

[Lucas Meneghel Rodrigues <lmr@redhat.com>]

Use the serial port for printf() and use the Bochs bios exit
port if the testdev port isn't available.

This unconditionally switches to use the serial port but tries
to use the testdev exit port since that lets you pass an exit
status.

This version puts the old behavior on an IFDEF block, as Avi
asked on the first review of the patch.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
---
 lib/x86/io.c |   60 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 59 insertions(+), 1 deletions(-)

diff --git a/lib/x86/io.c b/lib/x86/io.c
index 894f398..1f550b5 100644
--- a/lib/x86/io.c
+++ b/lib/x86/io.c
@@ -1,13 +1,58 @@
 #include "libcflat.h"
 #include "smp.h"
+#include "io.h"
+#ifndef USE_SERIAL
+#define USE_SERIAL
 
 static struct spinlock lock;
+static int serial_iobase = 0x3f8;
+static int serial_inited = 0;
+
+static void serial_outb(char ch)
+{
+        u8 lsr;
+
+        do {
+                lsr = inb(serial_iobase + 0x05);
+        } while (!(lsr & 0x20));
+
+        outb(ch, serial_iobase + 0x00);
+}
+
+static void serial_init(void)
+{
+        u8 lcr;
+
+        /* set DLAB */
+        lcr = inb(serial_iobase + 0x03);
+        lcr |= 0x80;
+        outb(lcr, serial_iobase + 0x03);
+
+        /* set baud rate to 115200 */
+        outb(0x01, serial_iobase + 0x00);
+        outb(0x00, serial_iobase + 0x01);
+
+        /* clear DLAB */
+        lcr = inb(serial_iobase + 0x03);
+        lcr &= ~0x80;
+        outb(lcr, serial_iobase + 0x03);
+}
 
 static void print_serial(const char *buf)
 {
 	unsigned long len = strlen(buf);
+#ifdef USE_SERIAL
+        unsigned long i;
+        if (!serial_inited) {
+            serial_init();
+        }
 
-	asm volatile ("rep/outsb" : "+S"(buf), "+c"(len) : "d"(0xf1));
+        for (i = 0; i < len; i++) {
+            serial_outb(buf[i]);
+        }
+#else
+        asm volatile ("rep/outsb" : "+S"(buf), "+c"(len) : "d"(0xf1));
+#endif
 }
 
 void puts(const char *s)
@@ -19,5 +64,18 @@ void puts(const char *s)
 
 void exit(int code)
 {
+#ifdef USE_SERIAL
+        static const char shutdown_str[8] = "Shutdown";
+        int i;
+
+        /* test device exit (with status) */
+        outl(code, 0xf4);
+
+        /* if that failed, try the Bochs poweroff port */
+        for (i = 0; i < 8; i++) {
+                outb(shutdown_str[i], 0x8900);
+        }
+#else
         asm volatile("out %0, %1" : : "a"(code), "d"((short)0xf4));
+#endif
 }
-- 
1.7.6