[Qemu-devel] [PATCH] Implement PC port80 debug register.

[Jordan Justen]

In PC systems, the byte I/O port 0x80 is commonly written to
by BIOS and/or system software as a simple checkpoint method.

This change adds an 'info port80' monitor command to retrieve
the last value written out to port80.

Signed-off-by: Jordan Justen <address@hidden>
---
 Makefile.target |    2 +-
 hw/pc.c         |    6 +---
 hw/pc.h         |    7 ++++
 hw/port80.c     |  104 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 monitor.c       |    6 +++
 5 files changed, 119 insertions(+), 6 deletions(-)
 create mode 100644 hw/port80.c

diff --git a/Makefile.target b/Makefile.target
index a593503..155d9c3 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -563,7 +563,7 @@ obj-y += wdt_ib700.o wdt_i6300esb.o
 ifeq ($(TARGET_BASE_ARCH), i386)
 # Hardware support
 obj-y += ide.o pckbd.o vga.o $(sound-obj-y) dma.o
-obj-y += fdc.o mc146818rtc.o serial.o i8259.o i8254.o pcspk.o pc.o
+obj-y += fdc.o mc146818rtc.o serial.o i8259.o i8254.o pcspk.o port80.o pc.o
 obj-y += cirrus_vga.o apic.o ioapic.o parallel.o acpi.o piix_pci.o
 obj-y += usb-uhci.o vmmouse.o vmport.o vmware_vga.o hpet.o
 obj-y += device-hotplug.o pci-hotplug.o smbios.o
diff --git a/hw/pc.c b/hw/pc.c
index 553ba5c..95ea295 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -87,10 +87,6 @@ static void option_rom_setup_reset(target_phys_addr_t addr, 
unsigned size)
     qemu_register_reset(option_rom_reset, rrd);
 }
 
-static void ioport80_write(void *opaque, uint32_t addr, uint32_t data)
-{
-}
-
 /* MSDOS compatibility mode FPU exception support */
 static qemu_irq ferr_irq;
 /* XXX: add IGNNE support */
@@ -1253,7 +1249,7 @@ static void pc_init1(ram_addr_t ram_size,
     }
 
     /* init basic PC hardware */
-    register_ioport_write(0x80, 1, 1, ioport80_write, NULL);
+    port80_init();
 
     register_ioport_write(0xf0, 1, 1, ioportF0_write, NULL);
 
diff --git a/hw/pc.h b/hw/pc.h
index 9fbae20..1d0423e 100644
--- a/hw/pc.h
+++ b/hw/pc.h
@@ -166,4 +166,11 @@ void pci_piix4_ide_init(PCIBus *bus, BlockDriverState 
**hd_table, int devfn,
 void isa_ne2000_init(int base, qemu_irq irq, NICInfo *nd);
 
 int cpu_is_bsp(CPUState *env);
+
+/* port80.c */
+
+typedef struct Port80State Port80State;
+
+Port80State *port80_init(void);
+
 #endif
diff --git a/hw/port80.c b/hw/port80.c
new file mode 100644
index 0000000..947b3cd
--- /dev/null
+++ b/hw/port80.c
@@ -0,0 +1,104 @@
+/*
+ * QEMU debug port 80 emulation
+ *
+ * Copyright (c) 2003-2004 Fabrice Bellard
+ * Copyright (c) 2009 Jordan Justen
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to 
deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#include "hw.h"
+#include "sysemu.h"
+#include "pc.h"
+#include "isa.h"
+#include "monitor.h"
+
+void do_monitor_info_port80(Monitor *mon);
+
+//#define DEBUG_PORT80
+//#define PORT80_READ_SUPPORT
+
+struct Port80State {
+    uint8_t data;
+};
+
+static Port80State *state;
+
+static void port80_ioport_write(void *opaque, uint32_t addr, uint32_t data)
+{
+    Port80State *s = opaque;
+
+#ifdef DEBUG_PORT80
+    printf("port%02x: write val=0x%02x\n", addr, data);
+#endif
+    s->data = data;
+}
+
+#ifdef PORT80_READ_SUPPORT
+static uint32_t port80_ioport_read(void *opaque, uint32_t addr)
+{
+    Port80State *s = opaque;
+    int ret;
+    ret = s->data;
+#ifdef DEBUG_PORT80
+    printf("port%02x: read val=0x%02x\n", addr, ret);
+#endif
+    return ret;
+}
+#endif
+
+static void port80_save(QEMUFile *f, void *opaque)
+{
+    Port80State *s = opaque;
+
+    qemu_put_byte(f, s->data);
+}
+
+static int port80_load(QEMUFile *f, void *opaque, int version_id)
+{
+    Port80State *s = opaque;
+
+    if (version_id != 1)
+        return -EINVAL;
+
+    s->data = qemu_get_byte(f);
+    state = s;
+    return 0;
+}
+
+void do_monitor_info_port80(Monitor *mon)
+{
+    monitor_printf(mon, "0x%02x\n", state->data);
+}
+
+Port80State *port80_init()
+{
+    Port80State *s;
+
+    s = qemu_mallocz(sizeof(Port80State));
+    state = s;
+
+    register_ioport_write(0x80, 1, 1, port80_ioport_write, s);
+#ifdef PORT80_READ_SUPPORT
+    register_ioport_read(0x80, 1, 1, port80_ioport_read, s);
+#endif
+
+    register_savevm("port80", 0x80, 1, port80_save, port80_load, s);
+    return s;
+}
+
diff --git a/monitor.c b/monitor.c
index bad79fe..a128d43 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1677,6 +1677,10 @@ static void do_acl_remove(Monitor *mon, const char 
*aclname, const char *match)
     }
 }
 
+#if defined(TARGET_I386)
+void do_monitor_info_port80(Monitor *mon);
+#endif
+
 static const mon_cmd_t mon_cmds[] = {
 #include "qemu-monitor.h"
     { NULL, NULL, },
@@ -1715,6 +1719,8 @@ static const mon_cmd_t info_cmds[] = {
       "", "show the active virtual memory mappings", },
     { "hpet", "", do_info_hpet,
       "", "show state of HPET", },
+    { "port80", "", do_monitor_info_port80,
+      "", "show value of the last write to i/o port 0x80", },
 #endif
     { "jit", "", do_info_jit,
       "", "show dynamic compiler info", },
-- 
1.6.0.4