Re: [Qemu-devel] [PATCH v2] ACPI: Enable AML DBUG() control method

[Paolo Bonzini <pbonzini@redhat.com>]

On 08/08/2016 09:26, Lv Zheng wrote:
> This patch enables DBUG() control method, making it independent of seabios.
> 
> DBUG() is defined in the default DSDT, and is used to dump the AML
> debugging information to the debug port. Thus it can be used by the ACPI
> open source community developers to probe the de-facto standard AML
> interpreter behavior.
> 
> But the debug IO port address used in DBUG() (DBG operation region field)
> is currently not synchronized to any debugging facility implemented in
> qemu.
> 
> Originally, we managed to use this feature by specifying
> "-global isa-debugcon.iobase=0x402 -debugcon stdio" to make it working with
> the debug console device. Note that the "iobase=0x402" implies that this
> feature is currently dependent on seabios.
> 
> But since the AML tables are now provided by qemu itself, this feature
> shouldn't be dependent on any BIOS rom. This patch thus changes DBG AML
> generation code using isa-debugcon iobase so that we can always use this
> feature by only specifying "-debugcon stdio".
> 
> Signed-off-by: Lv Zheng <lv.zheng@intel.com>
> ---
>  hw/char/debugcon.c         |   23 +++++++++++++++++++++++
>  hw/i386/acpi-build.c       |    4 +++-
>  include/hw/char/debugcon.h |   33 +++++++++++++++++++++++++++++++++
>  3 files changed, 59 insertions(+), 1 deletion(-)
>  create mode 100644 include/hw/char/debugcon.h
> 
> diff --git a/hw/char/debugcon.c b/hw/char/debugcon.c
> index e7f025e..7f70ec3 100644
> --- a/hw/char/debugcon.c
> +++ b/hw/char/debugcon.c
> @@ -30,6 +30,7 @@
>  #include "sysemu/char.h"
>  #include "hw/isa/isa.h"
>  #include "hw/i386/pc.h"
> +#include "hw/char/debugcon.h"
>  
>  #define TYPE_ISA_DEBUGCON_DEVICE "isa-debugcon"
>  #define ISA_DEBUGCON_DEVICE(obj) \
> @@ -134,6 +135,28 @@ static const TypeInfo debugcon_isa_info = {
>      .class_init    = debugcon_isa_class_initfn,
>  };
>  
> +static Object *debugcon_isa_find(void)
> +{
> +    bool ambig;
> +    Object *o = object_resolve_path_type("", TYPE_ISA_DEBUGCON_DEVICE,
> +                                         &ambig);
> +
> +    if (ambig) {
> +        return NULL;
> +    }
> +    return o;
> +}
> +
> +uint32_t debugcon_get_port(void)
> +{
> +    Object *obj = debugcon_isa_find();
> +
> +    if (obj) {
> +        return object_property_get_int(obj, "iobase", &error_abort);
> +    }
> +    return 0xe9;
> +}
> +
>  static void debugcon_register_types(void)
>  {
>      type_register_static(&debugcon_isa_info);
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index a26a4bb..ce7cbc5 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -44,6 +44,7 @@
>  #include "hw/acpi/tpm.h"
>  #include "sysemu/tpm_backend.h"
>  #include "hw/timer/mc146818rtc_regs.h"
> +#include "hw/char/debugcon.h"
>  #include "sysemu/numa.h"
>  
>  /* Supported chipsets: */
> @@ -1442,7 +1443,8 @@ 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(debugcon_get_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/hw/char/debugcon.h b/include/hw/char/debugcon.h
> new file mode 100644
> index 0000000..a2420fd
> --- /dev/null
> +++ b/include/hw/char/debugcon.h
> @@ -0,0 +1,33 @@
> +/*
> + * QEMU debug console emulation
> + *
> + * Copyright (c) 2016 Lv Zheng <lv.zheng@intel.com>
> + *
> + * 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.
> + */
> +
> +#ifndef HW_DEBUGCON_H
> +#define HW_DEBUGCON_H
> +
> +#include "hw/hw.h"
> +#include "sysemu/sysemu.h"
> +
> +extern uint32_t debugcon_get_port(void);
> +
> +#endif
> 

This should be okay, but will have to wait for QEMU 2.8.

Thanks,

Paolo