[Qemu-devel] [PATCH 3/3] kvm-unit-tests: make I/O more friendly to existing QEMU hardware

[Anthony Liguori]

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.

Signed-off-by: Anthony Liguori <address@hidden>

diff --git a/lib/x86/io.c b/lib/x86/io.c
index 894f398..edc9437 100644
--- a/lib/x86/io.c
+++ b/lib/x86/io.c
@@ -1,13 +1,53 @@
 #include "libcflat.h"
 #include "smp.h"
+#include "io.h"
 
 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);
+        unsigned long i;
 
-       asm volatile ("rep/outsb" : "+S"(buf), "+c"(len) : "d"(0xf1));
+        if (!serial_inited) {
+            serial_init();
+        }
+
+        for (i = 0; i < len; i++) {
+            serial_outb(buf[i]);
+        }
 }
 
 void puts(const char *s)
@@ -19,5 +59,14 @@ void puts(const char *s)
 
 void exit(int code)
 {
-        asm volatile("out %0, %1" : : "a"(code), "d"((short)0xf4));
+        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);
+        }
 }
-- 
1.7.0.4