Re: [Qemu-devel] [PATCH] debugcon: Add -debugport option to allow changing debug console port number

2016-08-07 Thread Zheng, Lv 
Hi, Michael

> From: Michael S. Tsirkin [mailto:m...@redhat.com]
> Subject: Re: [PATCH] debugcon: Add -debugport option to allow changing
> debug console port number
> 
> On Fri, Aug 05, 2016 at 06:19:39PM +0800, Lv Zheng wrote:
> > Changing debugcon port to 0x402 allows the seabios AML table pre-
> defined
> > DBUG() control method to be able to dump the AML debugging
> information to
> > the re-directed debugging console.
> >
> > If the debug port number is configurable, users can further specify a
> > proper IO port number for it to make external BIOS's debugging
> > facility functioning.
> >
> > Signed-off-by: Lv Zheng 
> 
> This doesn't look like a reasonable interface.
> 
> How will user know which io ports are safe to use,
> to avoid e.g. conflicts with pci devices?
> 
[Lv Zheng] 
OK, I'll just correct the acpi-build.c.

Thanks
Lv

> 
> 
> > ---
> >  hw/char/debugcon.c  |4 
> >  hw/i386/acpi-build.c|3 ++-
> >  include/sysemu/sysemu.h |1 +
> >  qemu-options.hx |9 +
> >  vl.c|   15 +++
> >  5 files changed, 31 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/char/debugcon.c b/hw/char/debugcon.c
> > index e7f025e..f966a09 100644
> > --- a/hw/char/debugcon.c
> > +++ b/hw/char/debugcon.c
> > @@ -105,6 +105,10 @@ static void debugcon_isa_realizefn(DeviceState
> *dev, Error **errp)
> >  error_propagate(errp, err);
> >  return;
> >  }
> > +if (debug_port != 0xe9) {
> > +qdev_prop_set_uint32(dev, "iobase", debug_port);
> > +qdev_prop_set_uint32(dev, "readback", debug_port);
> > +}
> >  memory_region_init_io(>io, OBJECT(dev), _ops, s,
> >TYPE_ISA_DEBUGCON_DEVICE, 1);
> >  memory_region_add_subregion(isa_address_space_io(d),
> > diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> > index a26a4bb..14c6224 100644
> > --- a/hw/i386/acpi-build.c
> > +++ b/hw/i386/acpi-build.c
> > @@ -1442,7 +1442,8 @@ static void build_dbg_aml(Aml *table)
> >  Aml *idx = aml_local(2);
> >
> >  aml_append(scope,
> > -   aml_operation_region("DBG", AML_SYSTEM_IO, aml_int(0x0402),
> 0x01));
> > +   aml_operation_region("DBG", AML_SYSTEM_IO,
> > +aml_int(debug_port), 0x01));
> >  field = aml_field("DBG", AML_BYTE_ACC, AML_NOLOCK,
> AML_PRESERVE);
> >  aml_append(field, aml_named_field("DBGB", 8));
> >  aml_append(scope, field);
> > diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
> > index ee7c760..9e0a30b 100644
> > --- a/include/sysemu/sysemu.h
> > +++ b/include/sysemu/sysemu.h
> > @@ -167,6 +167,7 @@ extern uint8_t qemu_extra_params_fw[2];
> >  extern QEMUClockType rtc_clock;
> >  extern const char *mem_path;
> >  extern int mem_prealloc;
> > +extern uint32_t debug_port;
> >
> >  #define MAX_NODES 128
> >  #define NUMA_NODE_UNASSIGNED MAX_NODES
> > diff --git a/qemu-options.hx b/qemu-options.hx
> > index a71aaf8..05aedce 100644
> > --- a/qemu-options.hx
> > +++ b/qemu-options.hx
> > @@ -3123,6 +3123,15 @@ The default device is @code{vc} in graphical
> mode and @code{stdio} in
> >  non graphical mode.
> >  ETEXI
> >
> > +DEF("debugport", HAS_ARG, QEMU_OPTION_debugport, \
> > +"-debugport n Specify debug IO port number\n",
> > +QEMU_ARCH_ALL)
> > +STEXI
> > +@item -debugport @var{n}
> > +@findex -debugport
> > +Specify the debug IO port number, default is 0xe9.
> > +ETEXI
> > +
> >  DEF("pidfile", HAS_ARG, QEMU_OPTION_pidfile, \
> >  "-pidfile file   write PID to 'file'\n", QEMU_ARCH_ALL)
> >  STEXI
> > diff --git a/vl.c b/vl.c
> > index e7c2c62..710e14d 100644
> > --- a/vl.c
> > +++ b/vl.c
> > @@ -178,6 +178,7 @@ bool boot_strict;
> >  uint8_t *boot_splash_filedata;
> >  size_t boot_splash_filedata_size;
> >  uint8_t qemu_extra_params_fw[2];
> > +uint32_t debug_port = 0xe9;
> >
> >  int icount_align_option;
> >
> > @@ -2584,6 +2585,17 @@ static int debugcon_parse(const char
> *devname)
> >  return 0;
> >  }
> >
> > +static void debugcon_parse_port(const char *arg)
> > +{
> > +uint32_t port;
> > +
> > +port = strtoul(arg, NULL, 0);
> > +if (port) {
> > +printf("Re-assign debug console to port 0x%08x.\n", port);
> > +debug_port = port;
> > +}
> > +}
> > +
> >  static gint machine_class_cmp(gconstpointer a, gconstpointer b)
> >  {
> >  const MachineClass *mc1 = a, *mc2 = b;
> > @@ -3580,6 +3592,9 @@ int main(int argc, char **argv, char **envp)
> >  case QEMU_OPTION_debugcon:
> >  add_device_config(DEV_DEBUGCON, optarg);
> >  break;
> > +case QEMU_OPTION_debugport:
> > +debugcon_parse_port(optarg);
> > +break;
> >  case QEMU_OPTION_loadvm:
> >  loadvm = optarg;
> >  break;
> > --
> > 1.7.10

Re: [Qemu-devel] [PATCH] debugcon: Add -debugport option to allow changing debug console port number

2016-08-07 Thread Michael S. Tsirkin 
On Fri, Aug 05, 2016 at 06:19:39PM +0800, Lv Zheng wrote:
> Changing debugcon port to 0x402 allows the seabios AML table pre-defined
> DBUG() control method to be able to dump the AML debugging information to
> the re-directed debugging console.
> 
> If the debug port number is configurable, users can further specify a
> proper IO port number for it to make external BIOS's debugging
> facility functioning.
> 
> Signed-off-by: Lv Zheng 

This doesn't look like a reasonable interface.

How will user know which io ports are safe to use,
to avoid e.g. conflicts with pci devices?



> ---
>  hw/char/debugcon.c  |4 
>  hw/i386/acpi-build.c|3 ++-
>  include/sysemu/sysemu.h |1 +
>  qemu-options.hx |9 +
>  vl.c|   15 +++
>  5 files changed, 31 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/char/debugcon.c b/hw/char/debugcon.c
> index e7f025e..f966a09 100644
> --- a/hw/char/debugcon.c
> +++ b/hw/char/debugcon.c
> @@ -105,6 +105,10 @@ static void debugcon_isa_realizefn(DeviceState *dev, 
> Error **errp)
>  error_propagate(errp, err);
>  return;
>  }
> +if (debug_port != 0xe9) {
> +qdev_prop_set_uint32(dev, "iobase", debug_port);
> +qdev_prop_set_uint32(dev, "readback", debug_port);
> +}
>  memory_region_init_io(>io, OBJECT(dev), _ops, s,
>TYPE_ISA_DEBUGCON_DEVICE, 1);
>  memory_region_add_subregion(isa_address_space_io(d),
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index a26a4bb..14c6224 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -1442,7 +1442,8 @@ static void build_dbg_aml(Aml *table)
>  Aml *idx = aml_local(2);
>  
>  aml_append(scope,
> -   aml_operation_region("DBG", AML_SYSTEM_IO, aml_int(0x0402), 0x01));
> +   aml_operation_region("DBG", AML_SYSTEM_IO,
> +aml_int(debug_port), 0x01));
>  field = aml_field("DBG", AML_BYTE_ACC, AML_NOLOCK, AML_PRESERVE);
>  aml_append(field, aml_named_field("DBGB", 8));
>  aml_append(scope, field);
> diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
> index ee7c760..9e0a30b 100644
> --- a/include/sysemu/sysemu.h
> +++ b/include/sysemu/sysemu.h
> @@ -167,6 +167,7 @@ extern uint8_t qemu_extra_params_fw[2];
>  extern QEMUClockType rtc_clock;
>  extern const char *mem_path;
>  extern int mem_prealloc;
> +extern uint32_t debug_port;
>  
>  #define MAX_NODES 128
>  #define NUMA_NODE_UNASSIGNED MAX_NODES
> diff --git a/qemu-options.hx b/qemu-options.hx
> index a71aaf8..05aedce 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -3123,6 +3123,15 @@ The default device is @code{vc} in graphical mode and 
> @code{stdio} in
>  non graphical mode.
>  ETEXI
>  
> +DEF("debugport", HAS_ARG, QEMU_OPTION_debugport, \
> +"-debugport n Specify debug IO port number\n",
> +QEMU_ARCH_ALL)
> +STEXI
> +@item -debugport @var{n}
> +@findex -debugport
> +Specify the debug IO port number, default is 0xe9.
> +ETEXI
> +
>  DEF("pidfile", HAS_ARG, QEMU_OPTION_pidfile, \
>  "-pidfile file   write PID to 'file'\n", QEMU_ARCH_ALL)
>  STEXI
> diff --git a/vl.c b/vl.c
> index e7c2c62..710e14d 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -178,6 +178,7 @@ bool boot_strict;
>  uint8_t *boot_splash_filedata;
>  size_t boot_splash_filedata_size;
>  uint8_t qemu_extra_params_fw[2];
> +uint32_t debug_port = 0xe9;
>  
>  int icount_align_option;
>  
> @@ -2584,6 +2585,17 @@ static int debugcon_parse(const char *devname)
>  return 0;
>  }
>  
> +static void debugcon_parse_port(const char *arg)
> +{
> +uint32_t port;
> +
> +port = strtoul(arg, NULL, 0);
> +if (port) {
> +printf("Re-assign debug console to port 0x%08x.\n", port);
> +debug_port = port;
> +}
> +}
> +
>  static gint machine_class_cmp(gconstpointer a, gconstpointer b)
>  {
>  const MachineClass *mc1 = a, *mc2 = b;
> @@ -3580,6 +3592,9 @@ int main(int argc, char **argv, char **envp)
>  case QEMU_OPTION_debugcon:
>  add_device_config(DEV_DEBUGCON, optarg);
>  break;
> +case QEMU_OPTION_debugport:
> +debugcon_parse_port(optarg);
> +break;
>  case QEMU_OPTION_loadvm:
>  loadvm = optarg;
>  break;
> -- 
> 1.7.10

Re: [Qemu-devel] [PATCH] debugcon: Add -debugport option to allow changing debug console port number

2016-08-05 Thread Zheng, Lv 
Hi,

> From: Paolo Bonzini [mailto:paolo.bonz...@gmail.com] On Behalf Of Paolo
> Bonzini
> Subject: Re: [PATCH] debugcon: Add -debugport option to allow changing
> debug console port number
> 
> 
> 
> On 05/08/2016 12:19, Lv Zheng wrote:
> > Changing debugcon port to 0x402 allows the seabios AML table pre-
> defined
> > DBUG() control method to be able to dump the AML debugging
> information to
> > the re-directed debugging console.
> >
> > If the debug port number is configurable, users can further specify a
> > proper IO port number for it to make external BIOS's debugging
> > facility functioning.
> >
> > Signed-off-by: Lv Zheng 
> 
> You can do this with
> 
>-global isa-debugcon.iobase=0x402
[Lv Zheng] 
Thanks for the information. :)

Best regards
Lv


> 
> Paolo
> 
> > ---
> >  hw/char/debugcon.c  |4 
> >  hw/i386/acpi-build.c|3 ++-
> >  include/sysemu/sysemu.h |1 +
> >  qemu-options.hx |9 +
> >  vl.c|   15 +++
> >  5 files changed, 31 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/char/debugcon.c b/hw/char/debugcon.c
> > index e7f025e..f966a09 100644
> > --- a/hw/char/debugcon.c
> > +++ b/hw/char/debugcon.c
> > @@ -105,6 +105,10 @@ static void debugcon_isa_realizefn(DeviceState
> *dev, Error **errp)
> >  error_propagate(errp, err);
> >  return;
> >  }
> > +if (debug_port != 0xe9) {
> > +qdev_prop_set_uint32(dev, "iobase", debug_port);
> > +qdev_prop_set_uint32(dev, "readback", debug_port);
> > +}
> >  memory_region_init_io(>io, OBJECT(dev), _ops, s,
> >TYPE_ISA_DEBUGCON_DEVICE, 1);
> >  memory_region_add_subregion(isa_address_space_io(d),
> > diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> > index a26a4bb..14c6224 100644
> > --- a/hw/i386/acpi-build.c
> > +++ b/hw/i386/acpi-build.c
> > @@ -1442,7 +1442,8 @@ static void build_dbg_aml(Aml *table)
> >  Aml *idx = aml_local(2);
> >
> >  aml_append(scope,
> > -   aml_operation_region("DBG", AML_SYSTEM_IO, aml_int(0x0402),
> 0x01));
> > +   aml_operation_region("DBG", AML_SYSTEM_IO,
> > +aml_int(debug_port), 0x01));
> >  field = aml_field("DBG", AML_BYTE_ACC, AML_NOLOCK,
> AML_PRESERVE);
> >  aml_append(field, aml_named_field("DBGB", 8));
> >  aml_append(scope, field);
> > diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
> > index ee7c760..9e0a30b 100644
> > --- a/include/sysemu/sysemu.h
> > +++ b/include/sysemu/sysemu.h
> > @@ -167,6 +167,7 @@ extern uint8_t qemu_extra_params_fw[2];
> >  extern QEMUClockType rtc_clock;
> >  extern const char *mem_path;
> >  extern int mem_prealloc;
> > +extern uint32_t debug_port;
> >
> >  #define MAX_NODES 128
> >  #define NUMA_NODE_UNASSIGNED MAX_NODES
> > diff --git a/qemu-options.hx b/qemu-options.hx
> > index a71aaf8..05aedce 100644
> > --- a/qemu-options.hx
> > +++ b/qemu-options.hx
> > @@ -3123,6 +3123,15 @@ The default device is @code{vc} in graphical
> mode and @code{stdio} in
> >  non graphical mode.
> >  ETEXI
> >
> > +DEF("debugport", HAS_ARG, QEMU_OPTION_debugport, \
> > +"-debugport n Specify debug IO port number\n",
> > +QEMU_ARCH_ALL)
> > +STEXI
> > +@item -debugport @var{n}
> > +@findex -debugport
> > +Specify the debug IO port number, default is 0xe9.
> > +ETEXI
> > +
> >  DEF("pidfile", HAS_ARG, QEMU_OPTION_pidfile, \
> >  "-pidfile file   write PID to 'file'\n", QEMU_ARCH_ALL)
> >  STEXI
> > diff --git a/vl.c b/vl.c
> > index e7c2c62..710e14d 100644
> > --- a/vl.c
> > +++ b/vl.c
> > @@ -178,6 +178,7 @@ bool boot_strict;
> >  uint8_t *boot_splash_filedata;
> >  size_t boot_splash_filedata_size;
> >  uint8_t qemu_extra_params_fw[2];
> > +uint32_t debug_port = 0xe9;
> >
> >  int icount_align_option;
> >
> > @@ -2584,6 +2585,17 @@ static int debugcon_parse(const char
> *devname)
> >  return 0;
> >  }
> >
> > +static void debugcon_parse_port(const char *arg)
> > +{
> > +uint32_t port;
> > +
> > +port = strtoul(arg, NULL, 0);
> > +if (port) {
> > +printf("Re-assign debug console to port 0x%08x.\n", port);
> > +debug_port = port;
> > +}
> > +}
> > +
> >  static gint machine_class_cmp(gconstpointer a, gconstpointer b)
> >  {
> >  const MachineClass *mc1 = a, *mc2 = b;
> > @@ -3580,6 +3592,9 @@ int main(int argc, char **argv, char **envp)
> >  case QEMU_OPTION_debugcon:
> >  add_device_config(DEV_DEBUGCON, optarg);
> >  break;
> > +case QEMU_OPTION_debugport:
> > +debugcon_parse_port(optarg);
> > +break;
> >  case QEMU_OPTION_loadvm:
> >  loadvm = optarg;
> >  break;
> >

Re: [Qemu-devel] [PATCH] debugcon: Add -debugport option to allow changing debug console port number

2016-08-05 Thread Zheng, Lv 
Hi,

> From: Igor Mammedov [mailto:imamm...@redhat.com]
> Subject: Re: [Qemu-devel] [PATCH] debugcon: Add -debugport option to
> allow changing debug console port number
> 
> On Fri,  5 Aug 2016 18:19:39 +0800
> Lv Zheng <lv.zh...@intel.com> wrote:
> 
> > Changing debugcon port to 0x402 allows the seabios AML table pre-
> defined
> > DBUG() control method to be able to dump the AML debugging
> information to
> > the re-directed debugging console.
> >
> > If the debug port number is configurable, users can further specify a
> > proper IO port number for it to make external BIOS's debugging
> > facility functioning.
> 
> there is no need for yet another CLI option that is being added here,
> just use usual '-device isa-debugcon,iobase=0x402,chardev=seabios"
> 

[Lv Zheng] 
OK, thanks for the information.

However, I feel that there are still improvements we can do here:
1. synchronizing DSDT's DBG operation region to debugcon iobase in acpi-build.c;
2. the readback should be automatically corrected by the isa-debugcon.iobase.
What do you think of this?
And if one of the above stuffs is useful, do you need me to send a revised 
patch?

Cheers
Lv

Re: [Qemu-devel] [PATCH] debugcon: Add -debugport option to allow changing debug console port number

2016-08-05 Thread Paolo Bonzini 


On 05/08/2016 12:19, Lv Zheng wrote:
> Changing debugcon port to 0x402 allows the seabios AML table pre-defined
> DBUG() control method to be able to dump the AML debugging information to
> the re-directed debugging console.
> 
> If the debug port number is configurable, users can further specify a
> proper IO port number for it to make external BIOS's debugging
> facility functioning.
> 
> Signed-off-by: Lv Zheng 

You can do this with

   -global isa-debugcon.iobase=0x402

Paolo

> ---
>  hw/char/debugcon.c  |4 
>  hw/i386/acpi-build.c|3 ++-
>  include/sysemu/sysemu.h |1 +
>  qemu-options.hx |9 +
>  vl.c|   15 +++
>  5 files changed, 31 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/char/debugcon.c b/hw/char/debugcon.c
> index e7f025e..f966a09 100644
> --- a/hw/char/debugcon.c
> +++ b/hw/char/debugcon.c
> @@ -105,6 +105,10 @@ static void debugcon_isa_realizefn(DeviceState *dev, 
> Error **errp)
>  error_propagate(errp, err);
>  return;
>  }
> +if (debug_port != 0xe9) {
> +qdev_prop_set_uint32(dev, "iobase", debug_port);
> +qdev_prop_set_uint32(dev, "readback", debug_port);
> +}
>  memory_region_init_io(>io, OBJECT(dev), _ops, s,
>TYPE_ISA_DEBUGCON_DEVICE, 1);
>  memory_region_add_subregion(isa_address_space_io(d),
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index a26a4bb..14c6224 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -1442,7 +1442,8 @@ static void build_dbg_aml(Aml *table)
>  Aml *idx = aml_local(2);
>  
>  aml_append(scope,
> -   aml_operation_region("DBG", AML_SYSTEM_IO, aml_int(0x0402), 0x01));
> +   aml_operation_region("DBG", AML_SYSTEM_IO,
> +aml_int(debug_port), 0x01));
>  field = aml_field("DBG", AML_BYTE_ACC, AML_NOLOCK, AML_PRESERVE);
>  aml_append(field, aml_named_field("DBGB", 8));
>  aml_append(scope, field);
> diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
> index ee7c760..9e0a30b 100644
> --- a/include/sysemu/sysemu.h
> +++ b/include/sysemu/sysemu.h
> @@ -167,6 +167,7 @@ extern uint8_t qemu_extra_params_fw[2];
>  extern QEMUClockType rtc_clock;
>  extern const char *mem_path;
>  extern int mem_prealloc;
> +extern uint32_t debug_port;
>  
>  #define MAX_NODES 128
>  #define NUMA_NODE_UNASSIGNED MAX_NODES
> diff --git a/qemu-options.hx b/qemu-options.hx
> index a71aaf8..05aedce 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -3123,6 +3123,15 @@ The default device is @code{vc} in graphical mode and 
> @code{stdio} in
>  non graphical mode.
>  ETEXI
>  
> +DEF("debugport", HAS_ARG, QEMU_OPTION_debugport, \
> +"-debugport n Specify debug IO port number\n",
> +QEMU_ARCH_ALL)
> +STEXI
> +@item -debugport @var{n}
> +@findex -debugport
> +Specify the debug IO port number, default is 0xe9.
> +ETEXI
> +
>  DEF("pidfile", HAS_ARG, QEMU_OPTION_pidfile, \
>  "-pidfile file   write PID to 'file'\n", QEMU_ARCH_ALL)
>  STEXI
> diff --git a/vl.c b/vl.c
> index e7c2c62..710e14d 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -178,6 +178,7 @@ bool boot_strict;
>  uint8_t *boot_splash_filedata;
>  size_t boot_splash_filedata_size;
>  uint8_t qemu_extra_params_fw[2];
> +uint32_t debug_port = 0xe9;
>  
>  int icount_align_option;
>  
> @@ -2584,6 +2585,17 @@ static int debugcon_parse(const char *devname)
>  return 0;
>  }
>  
> +static void debugcon_parse_port(const char *arg)
> +{
> +uint32_t port;
> +
> +port = strtoul(arg, NULL, 0);
> +if (port) {
> +printf("Re-assign debug console to port 0x%08x.\n", port);
> +debug_port = port;
> +}
> +}
> +
>  static gint machine_class_cmp(gconstpointer a, gconstpointer b)
>  {
>  const MachineClass *mc1 = a, *mc2 = b;
> @@ -3580,6 +3592,9 @@ int main(int argc, char **argv, char **envp)
>  case QEMU_OPTION_debugcon:
>  add_device_config(DEV_DEBUGCON, optarg);
>  break;
> +case QEMU_OPTION_debugport:
> +debugcon_parse_port(optarg);
> +break;
>  case QEMU_OPTION_loadvm:
>  loadvm = optarg;
>  break;
>

Re: [Qemu-devel] [PATCH] debugcon: Add -debugport option to allow changing debug console port number

2016-08-05 Thread Igor Mammedov 
On Fri,  5 Aug 2016 18:19:39 +0800
Lv Zheng  wrote:

> Changing debugcon port to 0x402 allows the seabios AML table pre-defined
> DBUG() control method to be able to dump the AML debugging information to
> the re-directed debugging console.
> 
> If the debug port number is configurable, users can further specify a
> proper IO port number for it to make external BIOS's debugging
> facility functioning.

there is no need for yet another CLI option that is being added here,
just use usual '-device isa-debugcon,iobase=0x402,chardev=seabios"

[Qemu-devel] [PATCH] debugcon: Add -debugport option to allow changing debug console port number

2016-08-05 Thread Lv Zheng 
Changing debugcon port to 0x402 allows the seabios AML table pre-defined
DBUG() control method to be able to dump the AML debugging information to
the re-directed debugging console.

If the debug port number is configurable, users can further specify a
proper IO port number for it to make external BIOS's debugging
facility functioning.

Signed-off-by: Lv Zheng 
---
 hw/char/debugcon.c  |4 
 hw/i386/acpi-build.c|3 ++-
 include/sysemu/sysemu.h |1 +
 qemu-options.hx |9 +
 vl.c|   15 +++
 5 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/hw/char/debugcon.c b/hw/char/debugcon.c
index e7f025e..f966a09 100644
--- a/hw/char/debugcon.c
+++ b/hw/char/debugcon.c
@@ -105,6 +105,10 @@ static void debugcon_isa_realizefn(DeviceState *dev, Error 
**errp)
 error_propagate(errp, err);
 return;
 }
+if (debug_port != 0xe9) {
+qdev_prop_set_uint32(dev, "iobase", debug_port);
+qdev_prop_set_uint32(dev, "readback", debug_port);
+}
 memory_region_init_io(>io, OBJECT(dev), _ops, s,
   TYPE_ISA_DEBUGCON_DEVICE, 1);
 memory_region_add_subregion(isa_address_space_io(d),
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index a26a4bb..14c6224 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -1442,7 +1442,8 @@ static void build_dbg_aml(Aml *table)
 Aml *idx = aml_local(2);
 
 aml_append(scope,
-   aml_operation_region("DBG", AML_SYSTEM_IO, aml_int(0x0402), 0x01));
+   aml_operation_region("DBG", AML_SYSTEM_IO,
+aml_int(debug_port), 0x01));
 field = aml_field("DBG", AML_BYTE_ACC, AML_NOLOCK, AML_PRESERVE);
 aml_append(field, aml_named_field("DBGB", 8));
 aml_append(scope, field);
diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index ee7c760..9e0a30b 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -167,6 +167,7 @@ extern uint8_t qemu_extra_params_fw[2];
 extern QEMUClockType rtc_clock;
 extern const char *mem_path;
 extern int mem_prealloc;
+extern uint32_t debug_port;
 
 #define MAX_NODES 128
 #define NUMA_NODE_UNASSIGNED MAX_NODES
diff --git a/qemu-options.hx b/qemu-options.hx
index a71aaf8..05aedce 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -3123,6 +3123,15 @@ The default device is @code{vc} in graphical mode and 
@code{stdio} in
 non graphical mode.
 ETEXI
 
+DEF("debugport", HAS_ARG, QEMU_OPTION_debugport, \
+"-debugport n Specify debug IO port number\n",
+QEMU_ARCH_ALL)
+STEXI
+@item -debugport @var{n}
+@findex -debugport
+Specify the debug IO port number, default is 0xe9.
+ETEXI
+
 DEF("pidfile", HAS_ARG, QEMU_OPTION_pidfile, \
 "-pidfile file   write PID to 'file'\n", QEMU_ARCH_ALL)
 STEXI
diff --git a/vl.c b/vl.c
index e7c2c62..710e14d 100644
--- a/vl.c
+++ b/vl.c
@@ -178,6 +178,7 @@ bool boot_strict;
 uint8_t *boot_splash_filedata;
 size_t boot_splash_filedata_size;
 uint8_t qemu_extra_params_fw[2];
+uint32_t debug_port = 0xe9;
 
 int icount_align_option;
 
@@ -2584,6 +2585,17 @@ static int debugcon_parse(const char *devname)
 return 0;
 }
 
+static void debugcon_parse_port(const char *arg)
+{
+uint32_t port;
+
+port = strtoul(arg, NULL, 0);
+if (port) {
+printf("Re-assign debug console to port 0x%08x.\n", port);
+debug_port = port;
+}
+}
+
 static gint machine_class_cmp(gconstpointer a, gconstpointer b)
 {
 const MachineClass *mc1 = a, *mc2 = b;
@@ -3580,6 +3592,9 @@ int main(int argc, char **argv, char **envp)
 case QEMU_OPTION_debugcon:
 add_device_config(DEV_DEBUGCON, optarg);
 break;
+case QEMU_OPTION_debugport:
+debugcon_parse_port(optarg);
+break;
 case QEMU_OPTION_loadvm:
 loadvm = optarg;
 break;
-- 
1.7.10