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

[Zheng, Lv]

Hi, Michael

> From: Michael S. Tsirkin [mailto:address@hidden
> 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 <address@hidden>
> 
> 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(&s->io, OBJECT(dev), &debugcon_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
> > address@hidden -debugport @var{n}
> > address@hidden -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