diff mbox

[v6,5/6] acpi: Add IPMI table entries

Message ID 1464025217-24054-6-git-send-email-minyard@acm.org (mailing list archive)
State New, archived
Headers show

Commit Message

Corey Minyard May 23, 2016, 5:40 p.m. UTC
From: Corey Minyard <cminyard@mvista.com>

Use the new ACPI table construction tools to create an ACPI
entry for IPMI.  This adds a function called from build_dsdt
to add an DSDT entry for IPMI if IPMI is compiled in and has
registered firmware.  It also adds a dummy function if IPMI
is not compiled in.

This conforms to section "C3-2 Locating IPMI System Interfaces in
ACPI Name Space" in the IPMI 2.0 specification.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
---
 hw/acpi/Makefile.objs  |   2 +
 hw/acpi/ipmi.c         | 105 +++++++++++++++++++++++++++++++++++++++++++++++++
 hw/i386/acpi-build.c   |  24 +++++++++--
 hw/stubs/Makefile.objs |   1 +
 hw/stubs/acpi_ipmi.c   |  14 +++++++
 include/hw/acpi/ipmi.h |  22 +++++++++++
 6 files changed, 165 insertions(+), 3 deletions(-)
 create mode 100644 hw/acpi/ipmi.c
 create mode 100644 hw/stubs/acpi_ipmi.c
 create mode 100644 include/hw/acpi/ipmi.h

Comments

Igor Mammedov May 24, 2016, 7:49 a.m. UTC | #1
On Mon, 23 May 2016 12:40:16 -0500
minyard@acm.org wrote:

> From: Corey Minyard <cminyard@mvista.com>
> 
> Use the new ACPI table construction tools to create an ACPI
> entry for IPMI.  This adds a function called from build_dsdt
> to add an DSDT entry for IPMI if IPMI is compiled in and has
> registered firmware.  It also adds a dummy function if IPMI
> is not compiled in.
> 
> This conforms to section "C3-2 Locating IPMI System Interfaces in
> ACPI Name Space" in the IPMI 2.0 specification.
> 
> Signed-off-by: Corey Minyard <cminyard@mvista.com>
> ---
>  hw/acpi/Makefile.objs  |   2 +
>  hw/acpi/ipmi.c         | 105 +++++++++++++++++++++++++++++++++++++++++++++++++
>  hw/i386/acpi-build.c   |  24 +++++++++--
>  hw/stubs/Makefile.objs |   1 +
>  hw/stubs/acpi_ipmi.c   |  14 +++++++
>  include/hw/acpi/ipmi.h |  22 +++++++++++
>  6 files changed, 165 insertions(+), 3 deletions(-)
>  create mode 100644 hw/acpi/ipmi.c
>  create mode 100644 hw/stubs/acpi_ipmi.c
>  create mode 100644 include/hw/acpi/ipmi.h
> 
> diff --git a/hw/acpi/Makefile.objs b/hw/acpi/Makefile.objs
> index faee86c..95824e8 100644
> --- a/hw/acpi/Makefile.objs
> +++ b/hw/acpi/Makefile.objs
> @@ -6,3 +6,5 @@ obj-$(CONFIG_ACPI_NVDIMM) += nvdimm.o
>  common-obj-$(CONFIG_ACPI) += acpi_interface.o
>  common-obj-$(CONFIG_ACPI) += bios-linker-loader.o
>  common-obj-$(CONFIG_ACPI) += aml-build.o
> +common-obj-$(call land,$(CONFIG_ACPI),$(CONFIG_IPMI)) += ipmi.o
> +
> diff --git a/hw/acpi/ipmi.c b/hw/acpi/ipmi.c
> new file mode 100644
> index 0000000..201f824
> --- /dev/null
> +++ b/hw/acpi/ipmi.c
> @@ -0,0 +1,105 @@
> +/*
> + * IPMI ACPI firmware handling
> + *
> + * Copyright (c) 2015 Corey Minyard, MontaVista Software, LLC
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "hw/ipmi/ipmi.h"
> +#include "hw/acpi/aml-build.h"
> +#include "hw/acpi/acpi.h"
> +#include "hw/acpi/ipmi.h"
> +
> +static Aml *aml_ipmi_crs(IPMIFwInfo *info)
> +{
> +    Aml *crs = aml_resource_template();
> +    uint8_t regspacing = info->register_spacing;
nit about naming,
why not s/regspacing|register_spacing/reg_alignment/

> +
> +    /*
> +     * The base address is fixed and cannot change.  That may be different
> +     * if someone does PCI, but we aren't there yet.
> +     */
> +    switch (info->memspace) {
> +    case IPMI_MEMSPACE_IO:
> +        aml_append(crs, aml_io(AML_DECODE16, info->base_address,
> +                               info->base_address + info->register_length - 1,
> +                               regspacing, info->register_length));
> +        break;
> +    case IPMI_MEMSPACE_MEM32:
> +        aml_append(crs,
> +                   aml_dword_memory(AML_POS_DECODE,
> +                            AML_MIN_FIXED, AML_MAX_FIXED,
> +                            AML_NON_CACHEABLE, AML_READ_WRITE,
> +                            0xffffffff,
> +                            info->base_address,
> +                            info->base_address + info->register_length - 1,
> +                            regspacing, info->register_length));
> +        break;
> +    case IPMI_MEMSPACE_MEM64:
> +        aml_append(crs,
> +                   aml_qword_memory(AML_POS_DECODE,
> +                            AML_MIN_FIXED, AML_MAX_FIXED,
> +                            AML_NON_CACHEABLE, AML_READ_WRITE,
> +                            0xffffffffffffffffULL,
> +                            info->base_address,
> +                            info->base_address + info->register_length - 1,
> +                            regspacing, info->register_length));
> +        break;
> +    case IPMI_MEMSPACE_SMBUS:
> +        aml_append(crs, aml_return(aml_int(info->base_address)));
> +        break;
> +    default:
> +        abort();
> +    }
> +
> +    if (info->interrupt_number) {
> +        aml_append(crs, aml_irq_no_flags(info->interrupt_number));
> +    }
> +
> +    return crs;
> +}
> +
> +static Aml *aml_ipmi_device(IPMIFwInfo *info)
> +{
> +    Aml *dev;
> +    uint16_t version = ((info->ipmi_spec_major_revision << 8)
> +                        | (info->ipmi_spec_minor_revision << 4));
revisions potentially could silently overlap when ORed,
add assert to make sure the it won't go unnoticed.

> +
> +    dev = aml_device("MI%d", info->uuid);
> +    aml_append(dev, aml_name_decl("_HID", aml_eisaid("IPI0001")));
> +    aml_append(dev, aml_name_decl("_STR", aml_string("ipmi_%s",
> +                                                     info->interface_name)));
> +    aml_append(dev, aml_name_decl("_UID", aml_int(info->uuid)));
> +    aml_append(dev, aml_name_decl("_CRS", aml_ipmi_crs(info)));
> +    aml_append(dev, aml_name_decl("_IFT", aml_int(info->interface_type)));
> +    aml_append(dev, aml_name_decl("_SRV", aml_int(version)));
> +
> +    return dev;
> +}
> +
> +void build_acpi_ipmi_devices(Aml *scope, BusState *bus)
> +{
> +
> +    BusChild *kid;
> +
> +    QTAILQ_FOREACH(kid, &bus->children,  sibling) {
> +        DeviceState *dev = kid->child;
another nit,
not necessary just use OBJECT(kid->child)

> +        Object *obj = object_dynamic_cast(OBJECT(dev), TYPE_IPMI_INTERFACE);
put it below IPMIFwInfo info; to make it prettier :)

> +        IPMIInterface *ii;
> +        IPMIInterfaceClass *iic;
> +        IPMIFwInfo info;

> +
> +        if (!obj) {
> +            continue;
> +        }
> +
> +        ii = IPMI_INTERFACE(obj);
> +        iic = IPMI_INTERFACE_GET_CLASS(obj);
> +        memset(&info, 0, sizeof(info));
why not to put memset() inside iic->get_fwinfo(),
that way every caller won't have to do it  (SMBIOS call site).

> +        iic->get_fwinfo(ii, &info);
> +        aml_append(scope, aml_ipmi_device(&info));
> +    }
> +}
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index 279f0d7..bf9253d 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -59,6 +59,8 @@
>  #include "qapi/qmp/qint.h"
>  #include "qom/qom-qobject.h"
>  
> +#include "hw/acpi/ipmi.h"
> +
>  /* These are used to size the ACPI tables for -M pc-i440fx-1.7 and
>   * -M pc-i440fx-2.0.  Even if the actual amount of AML generated grows
>   * a little bit, there should be plenty of free space since the DSDT
> @@ -1445,7 +1447,21 @@ static Aml *build_com_device_aml(uint8_t uid)
>      return dev;
>  }
>  
> -static void build_isa_devices_aml(Aml *table)
> +static void build_isa_ipmi_aml(Aml *scope)
> +{
> +    bool ambiguous;
> +    Object *obj = object_resolve_path_type("", TYPE_ISA_BUS, &ambiguous);
> +
> +    if (ambiguous) {
> +        error_report("Multiple ISA busses, unable to define IPMI ACPI data");
> +    } else if (!obj) {
> +        error_report("No ISA bus, unable to define IPMI ACPI data");
> +    } else {
> +        build_acpi_ipmi_devices(scope, BUS(obj));
> +    }
> +}
I'd fold this function into build_acpi_ipmi_devices() if there aren't any plans
for IPMI devices being present on another bus.

> +
> +static void build_isa_devices_aml(Aml *table, PCMachineState *pcms)
why is pcms is added here, it doesn't seem to be used?

>  {
>      ISADevice *fdc = pc_find_fdc0();
>  
> @@ -1461,6 +1477,8 @@ static void build_isa_devices_aml(Aml *table)
>      aml_append(scope, build_com_device_aml(1));
>      aml_append(scope, build_com_device_aml(2));
>  
> +    build_isa_ipmi_aml(scope);
> +
>      aml_append(table, scope);
>  }
>  
> @@ -2011,7 +2029,7 @@ build_dsdt(GArray *table_data, GArray *linker,
>          build_hpet_aml(dsdt);
>          build_piix4_pm(dsdt);
>          build_piix4_isa_bridge(dsdt);
> -        build_isa_devices_aml(dsdt);
> +        build_isa_devices_aml(dsdt, pcms);
>          build_piix4_pci_hotplug(dsdt);
>          build_piix4_pci0_int(dsdt);
>      } else {
> @@ -2039,7 +2057,7 @@ build_dsdt(GArray *table_data, GArray *linker,
>  
>          build_hpet_aml(dsdt);
>          build_q35_isa_bridge(dsdt);
> -        build_isa_devices_aml(dsdt);
> +        build_isa_devices_aml(dsdt, pcms);
>          build_q35_pci0_int(dsdt);
>      }
>  
> diff --git a/hw/stubs/Makefile.objs b/hw/stubs/Makefile.objs
> index 60047e6..f09ea33 100644
> --- a/hw/stubs/Makefile.objs
> +++ b/hw/stubs/Makefile.objs
> @@ -1 +1,2 @@
>  stub-obj-$(CONFIG_SMBIOS) += smbios_type_38.o
> +stub-obj-$(CONFIG_ACPI) += acpi_ipmi.o
> \ No newline at end of file
> diff --git a/hw/stubs/acpi_ipmi.c b/hw/stubs/acpi_ipmi.c
> new file mode 100644
> index 0000000..e83fc19
> --- /dev/null
> +++ b/hw/stubs/acpi_ipmi.c
> @@ -0,0 +1,14 @@
> +/*
> + * IPMI ACPI firmware handling
> + *
> + * Copyright (c) 2015 Corey Minyard, MontaVista Software, LLC
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + */
> +
> +#include "hw/acpi/ipmi.h"
> +
> +void build_acpi_ipmi_devices(Aml *table, BusState *bus)
> +{
> +}
> diff --git a/include/hw/acpi/ipmi.h b/include/hw/acpi/ipmi.h
> new file mode 100644
> index 0000000..ca5043a
> --- /dev/null
> +++ b/include/hw/acpi/ipmi.h
> @@ -0,0 +1,22 @@
> +/*
> + * QEMU IPMI ACPI handling
> + *
> + * Copyright (c) 2015 Corey Minyard <cminyard@mvista.com>
s/2015/2016/ throughout series???


> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + */
> +#ifndef HW_ACPI_IPMI_H
> +#define HW_ACPI_IPMI_H
> +
> +#include "qemu/osdep.h"
> +#include "hw/acpi/aml-build.h"
> +
> +/*
> + * Add ACPI IPMI entries for all registered IPMI devices whose parent
> + * bus matches the given bus.  The resource is the ACPI resource that
> + * contains the IPMI device, this is required for the I2C CRS.
> + */
> +void build_acpi_ipmi_devices(Aml *table, BusState *bus);
> +
> +#endif /* HW_ACPI_IPMI_H */
Corey Minyard May 24, 2016, 12:41 p.m. UTC | #2
On 05/24/2016 02:49 AM, Igor Mammedov wrote:
> On Mon, 23 May 2016 12:40:16 -0500
> minyard@acm.org wrote:
>
>> From: Corey Minyard <cminyard@mvista.com>
>>
>> Use the new ACPI table construction tools to create an ACPI
>> entry for IPMI.  This adds a function called from build_dsdt
>> to add an DSDT entry for IPMI if IPMI is compiled in and has
>> registered firmware.  It also adds a dummy function if IPMI
>> is not compiled in.
>>
>> This conforms to section "C3-2 Locating IPMI System Interfaces in
>> ACPI Name Space" in the IPMI 2.0 specification.
>>
>> Signed-off-by: Corey Minyard <cminyard@mvista.com>
>> ---
>>   hw/acpi/Makefile.objs  |   2 +
>>   hw/acpi/ipmi.c         | 105 +++++++++++++++++++++++++++++++++++++++++++++++++
>>   hw/i386/acpi-build.c   |  24 +++++++++--
>>   hw/stubs/Makefile.objs |   1 +
>>   hw/stubs/acpi_ipmi.c   |  14 +++++++
>>   include/hw/acpi/ipmi.h |  22 +++++++++++
>>   6 files changed, 165 insertions(+), 3 deletions(-)
>>   create mode 100644 hw/acpi/ipmi.c
>>   create mode 100644 hw/stubs/acpi_ipmi.c
>>   create mode 100644 include/hw/acpi/ipmi.h
>>
>> diff --git a/hw/acpi/Makefile.objs b/hw/acpi/Makefile.objs
>> index faee86c..95824e8 100644
>> --- a/hw/acpi/Makefile.objs
>> +++ b/hw/acpi/Makefile.objs
>> @@ -6,3 +6,5 @@ obj-$(CONFIG_ACPI_NVDIMM) += nvdimm.o
>>   common-obj-$(CONFIG_ACPI) += acpi_interface.o
>>   common-obj-$(CONFIG_ACPI) += bios-linker-loader.o
>>   common-obj-$(CONFIG_ACPI) += aml-build.o
>> +common-obj-$(call land,$(CONFIG_ACPI),$(CONFIG_IPMI)) += ipmi.o
>> +
>> diff --git a/hw/acpi/ipmi.c b/hw/acpi/ipmi.c
>> new file mode 100644
>> index 0000000..201f824
>> --- /dev/null
>> +++ b/hw/acpi/ipmi.c
>> @@ -0,0 +1,105 @@
>> +/*
>> + * IPMI ACPI firmware handling
>> + *
>> + * Copyright (c) 2015 Corey Minyard, MontaVista Software, LLC
>> + *
>> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
>> + * See the COPYING file in the top-level directory.
>> + */
>> +
>> +#include "qemu/osdep.h"
>> +#include "hw/ipmi/ipmi.h"
>> +#include "hw/acpi/aml-build.h"
>> +#include "hw/acpi/acpi.h"
>> +#include "hw/acpi/ipmi.h"
>> +
>> +static Aml *aml_ipmi_crs(IPMIFwInfo *info)
>> +{
>> +    Aml *crs = aml_resource_template();
>> +    uint8_t regspacing = info->register_spacing;
> nit about naming,
> why not s/regspacing|register_spacing/reg_alignment/

"Register spacing" comes from the SMBIOS definition in the IPMI spec.  
Since I did SMBIOS first, it won.

There's no reason to have a local for this now (I think there was at 
some point).

.
.
.

>> +
>> +        if (!obj) {
>> +            continue;
>> +        }
>> +
>> +        ii = IPMI_INTERFACE(obj);
>> +        iic = IPMI_INTERFACE_GET_CLASS(obj);
>> +        memset(&info, 0, sizeof(info));
> why not to put memset() inside iic->get_fwinfo(),
> that way every caller won't have to do it  (SMBIOS call site).

I debated on that, but there are actually fewer call sites than
implementers here.  Well, they are equal now, but with SMBus
there will be more implementers.

>> +        iic->get_fwinfo(ii, &info);
>> +        aml_append(scope, aml_ipmi_device(&info));
>> +    }
>> +}
>> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
>> index 279f0d7..bf9253d 100644
>> --- a/hw/i386/acpi-build.c
>> +++ b/hw/i386/acpi-build.c
>> @@ -59,6 +59,8 @@
>>   #include "qapi/qmp/qint.h"
>>   #include "qom/qom-qobject.h"
>>   
>> +#include "hw/acpi/ipmi.h"
>> +
>>   /* These are used to size the ACPI tables for -M pc-i440fx-1.7 and
>>    * -M pc-i440fx-2.0.  Even if the actual amount of AML generated grows
>>    * a little bit, there should be plenty of free space since the DSDT
>> @@ -1445,7 +1447,21 @@ static Aml *build_com_device_aml(uint8_t uid)
>>       return dev;
>>   }
>>   
>> -static void build_isa_devices_aml(Aml *table)
>> +static void build_isa_ipmi_aml(Aml *scope)
>> +{
>> +    bool ambiguous;
>> +    Object *obj = object_resolve_path_type("", TYPE_ISA_BUS, &ambiguous);
>> +
>> +    if (ambiguous) {
>> +        error_report("Multiple ISA busses, unable to define IPMI ACPI data");
>> +    } else if (!obj) {
>> +        error_report("No ISA bus, unable to define IPMI ACPI data");
>> +    } else {
>> +        build_acpi_ipmi_devices(scope, BUS(obj));
>> +    }
>> +}
> I'd fold this function into build_acpi_ipmi_devices() if there aren't any plans
> for IPMI devices being present on another bus.

Ok, it looked a little neater this way to me, but that's fine.

>> +
>> +static void build_isa_devices_aml(Aml *table, PCMachineState *pcms)
> why is pcms is added here, it doesn't seem to be used?

I forgot to remove it when I removed the isa_bus from PCMachineState.

Thanks,

-corey
diff mbox

Patch

diff --git a/hw/acpi/Makefile.objs b/hw/acpi/Makefile.objs
index faee86c..95824e8 100644
--- a/hw/acpi/Makefile.objs
+++ b/hw/acpi/Makefile.objs
@@ -6,3 +6,5 @@  obj-$(CONFIG_ACPI_NVDIMM) += nvdimm.o
 common-obj-$(CONFIG_ACPI) += acpi_interface.o
 common-obj-$(CONFIG_ACPI) += bios-linker-loader.o
 common-obj-$(CONFIG_ACPI) += aml-build.o
+common-obj-$(call land,$(CONFIG_ACPI),$(CONFIG_IPMI)) += ipmi.o
+
diff --git a/hw/acpi/ipmi.c b/hw/acpi/ipmi.c
new file mode 100644
index 0000000..201f824
--- /dev/null
+++ b/hw/acpi/ipmi.c
@@ -0,0 +1,105 @@ 
+/*
+ * IPMI ACPI firmware handling
+ *
+ * Copyright (c) 2015 Corey Minyard, MontaVista Software, LLC
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "hw/ipmi/ipmi.h"
+#include "hw/acpi/aml-build.h"
+#include "hw/acpi/acpi.h"
+#include "hw/acpi/ipmi.h"
+
+static Aml *aml_ipmi_crs(IPMIFwInfo *info)
+{
+    Aml *crs = aml_resource_template();
+    uint8_t regspacing = info->register_spacing;
+
+    /*
+     * The base address is fixed and cannot change.  That may be different
+     * if someone does PCI, but we aren't there yet.
+     */
+    switch (info->memspace) {
+    case IPMI_MEMSPACE_IO:
+        aml_append(crs, aml_io(AML_DECODE16, info->base_address,
+                               info->base_address + info->register_length - 1,
+                               regspacing, info->register_length));
+        break;
+    case IPMI_MEMSPACE_MEM32:
+        aml_append(crs,
+                   aml_dword_memory(AML_POS_DECODE,
+                            AML_MIN_FIXED, AML_MAX_FIXED,
+                            AML_NON_CACHEABLE, AML_READ_WRITE,
+                            0xffffffff,
+                            info->base_address,
+                            info->base_address + info->register_length - 1,
+                            regspacing, info->register_length));
+        break;
+    case IPMI_MEMSPACE_MEM64:
+        aml_append(crs,
+                   aml_qword_memory(AML_POS_DECODE,
+                            AML_MIN_FIXED, AML_MAX_FIXED,
+                            AML_NON_CACHEABLE, AML_READ_WRITE,
+                            0xffffffffffffffffULL,
+                            info->base_address,
+                            info->base_address + info->register_length - 1,
+                            regspacing, info->register_length));
+        break;
+    case IPMI_MEMSPACE_SMBUS:
+        aml_append(crs, aml_return(aml_int(info->base_address)));
+        break;
+    default:
+        abort();
+    }
+
+    if (info->interrupt_number) {
+        aml_append(crs, aml_irq_no_flags(info->interrupt_number));
+    }
+
+    return crs;
+}
+
+static Aml *aml_ipmi_device(IPMIFwInfo *info)
+{
+    Aml *dev;
+    uint16_t version = ((info->ipmi_spec_major_revision << 8)
+                        | (info->ipmi_spec_minor_revision << 4));
+
+    dev = aml_device("MI%d", info->uuid);
+    aml_append(dev, aml_name_decl("_HID", aml_eisaid("IPI0001")));
+    aml_append(dev, aml_name_decl("_STR", aml_string("ipmi_%s",
+                                                     info->interface_name)));
+    aml_append(dev, aml_name_decl("_UID", aml_int(info->uuid)));
+    aml_append(dev, aml_name_decl("_CRS", aml_ipmi_crs(info)));
+    aml_append(dev, aml_name_decl("_IFT", aml_int(info->interface_type)));
+    aml_append(dev, aml_name_decl("_SRV", aml_int(version)));
+
+    return dev;
+}
+
+void build_acpi_ipmi_devices(Aml *scope, BusState *bus)
+{
+
+    BusChild *kid;
+
+    QTAILQ_FOREACH(kid, &bus->children,  sibling) {
+        DeviceState *dev = kid->child;
+        Object *obj = object_dynamic_cast(OBJECT(dev), TYPE_IPMI_INTERFACE);
+        IPMIInterface *ii;
+        IPMIInterfaceClass *iic;
+        IPMIFwInfo info;
+
+        if (!obj) {
+            continue;
+        }
+
+        ii = IPMI_INTERFACE(obj);
+        iic = IPMI_INTERFACE_GET_CLASS(obj);
+        memset(&info, 0, sizeof(info));
+        iic->get_fwinfo(ii, &info);
+        aml_append(scope, aml_ipmi_device(&info));
+    }
+}
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 279f0d7..bf9253d 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -59,6 +59,8 @@ 
 #include "qapi/qmp/qint.h"
 #include "qom/qom-qobject.h"
 
+#include "hw/acpi/ipmi.h"
+
 /* These are used to size the ACPI tables for -M pc-i440fx-1.7 and
  * -M pc-i440fx-2.0.  Even if the actual amount of AML generated grows
  * a little bit, there should be plenty of free space since the DSDT
@@ -1445,7 +1447,21 @@  static Aml *build_com_device_aml(uint8_t uid)
     return dev;
 }
 
-static void build_isa_devices_aml(Aml *table)
+static void build_isa_ipmi_aml(Aml *scope)
+{
+    bool ambiguous;
+    Object *obj = object_resolve_path_type("", TYPE_ISA_BUS, &ambiguous);
+
+    if (ambiguous) {
+        error_report("Multiple ISA busses, unable to define IPMI ACPI data");
+    } else if (!obj) {
+        error_report("No ISA bus, unable to define IPMI ACPI data");
+    } else {
+        build_acpi_ipmi_devices(scope, BUS(obj));
+    }
+}
+
+static void build_isa_devices_aml(Aml *table, PCMachineState *pcms)
 {
     ISADevice *fdc = pc_find_fdc0();
 
@@ -1461,6 +1477,8 @@  static void build_isa_devices_aml(Aml *table)
     aml_append(scope, build_com_device_aml(1));
     aml_append(scope, build_com_device_aml(2));
 
+    build_isa_ipmi_aml(scope);
+
     aml_append(table, scope);
 }
 
@@ -2011,7 +2029,7 @@  build_dsdt(GArray *table_data, GArray *linker,
         build_hpet_aml(dsdt);
         build_piix4_pm(dsdt);
         build_piix4_isa_bridge(dsdt);
-        build_isa_devices_aml(dsdt);
+        build_isa_devices_aml(dsdt, pcms);
         build_piix4_pci_hotplug(dsdt);
         build_piix4_pci0_int(dsdt);
     } else {
@@ -2039,7 +2057,7 @@  build_dsdt(GArray *table_data, GArray *linker,
 
         build_hpet_aml(dsdt);
         build_q35_isa_bridge(dsdt);
-        build_isa_devices_aml(dsdt);
+        build_isa_devices_aml(dsdt, pcms);
         build_q35_pci0_int(dsdt);
     }
 
diff --git a/hw/stubs/Makefile.objs b/hw/stubs/Makefile.objs
index 60047e6..f09ea33 100644
--- a/hw/stubs/Makefile.objs
+++ b/hw/stubs/Makefile.objs
@@ -1 +1,2 @@ 
 stub-obj-$(CONFIG_SMBIOS) += smbios_type_38.o
+stub-obj-$(CONFIG_ACPI) += acpi_ipmi.o
\ No newline at end of file
diff --git a/hw/stubs/acpi_ipmi.c b/hw/stubs/acpi_ipmi.c
new file mode 100644
index 0000000..e83fc19
--- /dev/null
+++ b/hw/stubs/acpi_ipmi.c
@@ -0,0 +1,14 @@ 
+/*
+ * IPMI ACPI firmware handling
+ *
+ * Copyright (c) 2015 Corey Minyard, MontaVista Software, LLC
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "hw/acpi/ipmi.h"
+
+void build_acpi_ipmi_devices(Aml *table, BusState *bus)
+{
+}
diff --git a/include/hw/acpi/ipmi.h b/include/hw/acpi/ipmi.h
new file mode 100644
index 0000000..ca5043a
--- /dev/null
+++ b/include/hw/acpi/ipmi.h
@@ -0,0 +1,22 @@ 
+/*
+ * QEMU IPMI ACPI handling
+ *
+ * Copyright (c) 2015 Corey Minyard <cminyard@mvista.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+#ifndef HW_ACPI_IPMI_H
+#define HW_ACPI_IPMI_H
+
+#include "qemu/osdep.h"
+#include "hw/acpi/aml-build.h"
+
+/*
+ * Add ACPI IPMI entries for all registered IPMI devices whose parent
+ * bus matches the given bus.  The resource is the ACPI resource that
+ * contains the IPMI device, this is required for the I2C CRS.
+ */
+void build_acpi_ipmi_devices(Aml *table, BusState *bus);
+
+#endif /* HW_ACPI_IPMI_H */