Patchwork [1/3] Make kvm64 the default cpu model when kvm_enabled()

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Submitter Joerg Roedel
Date Sept. 27, 2010, 1:16 p.m.
Message ID <1285593377-1754-2-git-send-email-joerg.roedel@amd.com>
Download mbox | patch
Permalink /patch/65847/
State New
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Comments

Joerg Roedel - Sept. 27, 2010, 1:16 p.m.
As requested by Alex this patch makes kvm64 the default CPU
model when qemu is started with -enable-kvm. This takes only
effect for qemu-versions newer or equal to 0.14.0.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
---
 hw/boards.h    |    1 +
 hw/pc.c        |   21 ++++++++++++++++-----
 hw/pc_piix.c   |    6 ++++++
 qemu-version.h |   35 +++++++++++++++++++++++++++++++++++
 vl.c           |    4 ++++
 5 files changed, 62 insertions(+), 5 deletions(-)
 create mode 100644 qemu-version.h
Marcelo Tosatti - Oct. 6, 2010, 6:53 p.m.
On Mon, Sep 27, 2010 at 03:16:15PM +0200, Joerg Roedel wrote:
> As requested by Alex this patch makes kvm64 the default CPU
> model when qemu is started with -enable-kvm. This takes only
> effect for qemu-versions newer or equal to 0.14.0.
> 
> Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
> ---
>  hw/boards.h    |    1 +
>  hw/pc.c        |   21 ++++++++++++++++-----
>  hw/pc_piix.c   |    6 ++++++
>  qemu-version.h |   35 +++++++++++++++++++++++++++++++++++
>  vl.c           |    4 ++++
>  5 files changed, 62 insertions(+), 5 deletions(-)
>  create mode 100644 qemu-version.h
> 
> diff --git a/hw/boards.h b/hw/boards.h
> index 6f0f0d7..2d41b2d 100644
> --- a/hw/boards.h
> +++ b/hw/boards.h
> @@ -19,6 +19,7 @@ typedef struct QEMUMachine {
>      QEMUMachineInitFunc *init;
>      int use_scsi;
>      int max_cpus;
> +    unsigned int compat_version;
>      unsigned int no_serial:1,
>          no_parallel:1,
>          use_virtcon:1,
> diff --git a/hw/pc.c b/hw/pc.c
> index 69b13bf..372ec4c 100644
> --- a/hw/pc.c
> +++ b/hw/pc.c
> @@ -40,6 +40,16 @@
>  #include "sysbus.h"
>  #include "sysemu.h"
>  #include "blockdev.h"
> +#include "kvm.h"
> +#include "qemu-version.h"
> +
> +#ifdef TARGET_X86_64
> +#define DEFAULT_KVM_CPU_MODEL "kvm64"
> +#define DEFAULT_QEMU_CPU_MODEL "qemu64"
> +#else
> +#define DEFAULT_KVM_CPU_MODEL "kvm32"
> +#define DEFAULT_QEMU_CPU_MODEL "qemu32"
> +#endif
>  
>  /* output Bochs bios info messages */
>  //#define DEBUG_BIOS
> @@ -867,11 +877,12 @@ void pc_cpus_init(const char *cpu_model)
>  
>      /* init CPUs */
>      if (cpu_model == NULL) {
> -#ifdef TARGET_X86_64
> -        cpu_model = "qemu64";
> -#else
> -        cpu_model = "qemu32";
> -#endif
> +        if (kvm_enabled() &&
> +            qemu_compat_version >= QEMU_COMPAT_VERSION(0, 14, 0)) {
> +            cpu_model = DEFAULT_KVM_CPU_MODEL;
> +        } else {
> +            cpu_model = DEFAULT_QEMU_CPU_MODEL;
> +        }
>      }
>  
>      for(i = 0; i < smp_cpus; i++) {
> diff --git a/hw/pc_piix.c b/hw/pc_piix.c
> index 12359a7..9e46b71 100644
> --- a/hw/pc_piix.c
> +++ b/hw/pc_piix.c
> @@ -35,6 +35,7 @@
>  #include "sysemu.h"
>  #include "sysbus.h"
>  #include "blockdev.h"
> +#include "qemu-version.h"
>  
>  #define MAX_IDE_BUS 2
>  
> @@ -217,6 +218,7 @@ static QEMUMachine pc_machine = {
>      .desc = "Standard PC",
>      .init = pc_init_pci,
>      .max_cpus = 255,
> +    .compat_version = QEMU_COMPAT_VERSION(0, 13, 0),
>      .is_default = 1,
>  };
>  
> @@ -225,6 +227,7 @@ static QEMUMachine pc_machine_v0_12 = {
>      .desc = "Standard PC",
>      .init = pc_init_pci,
>      .max_cpus = 255,
> +    .compat_version = QEMU_COMPAT_VERSION(0, 12, 0),
>      .compat_props = (GlobalProperty[]) {
>          {
>              .driver   = "virtio-serial-pci",
> @@ -244,6 +247,7 @@ static QEMUMachine pc_machine_v0_11 = {
>      .desc = "Standard PC, qemu 0.11",
>      .init = pc_init_pci,
>      .max_cpus = 255,
> +    .compat_version = QEMU_COMPAT_VERSION(0, 11, 0),
>      .compat_props = (GlobalProperty[]) {
>          {
>              .driver   = "virtio-blk-pci",
> @@ -279,6 +283,7 @@ static QEMUMachine pc_machine_v0_10 = {
>      .desc = "Standard PC, qemu 0.10",
>      .init = pc_init_pci,
>      .max_cpus = 255,
> +    .compat_version = QEMU_COMPAT_VERSION(0, 10, 0),
>      .compat_props = (GlobalProperty[]) {
>          {
>              .driver   = "virtio-blk-pci",
> @@ -325,6 +330,7 @@ static QEMUMachine isapc_machine = {
>      .name = "isapc",
>      .desc = "ISA-only PC",
>      .init = pc_init_isa,
> +    .compat_version = QEMU_COMPAT_VERSION(0, 10, 0),
>      .max_cpus = 1,
>  };
>  
> diff --git a/qemu-version.h b/qemu-version.h
> new file mode 100644
> index 0000000..b4bfe48
> --- /dev/null
> +++ b/qemu-version.h
> @@ -0,0 +1,35 @@
> +/*
> + * qemu-version.h
> + *
> + * Defines needed for handling QEMU version compatibility
> + *
> + * Copyright (c) 2010 Joerg Roedel <joerg.roedel@amd.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 _QEMU_VERSION_H_
> +#define _QEMU_VERSION_H_
> +
> +extern unsigned int qemu_compat_version;
> +
> +#define QEMU_COMPAT_VERSION(major, minor, patchlevel) \
> +        ((unsigned int)(major << 16) | (minor << 8) | (patchlevel))
> +
> +#endif
> diff --git a/vl.c b/vl.c
> index d352d18..37727f3 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -161,6 +161,7 @@ int main(int argc, char **argv)
>  #include "qemu-queue.h"
>  #include "cpus.h"
>  #include "arch_init.h"
> +#include "qemu-version.h"
>  
>  //#define DEBUG_NET
>  //#define DEBUG_SLIRP
> @@ -169,6 +170,7 @@ int main(int argc, char **argv)
>  
>  #define MAX_VIRTIO_CONSOLES 1
>  
> +unsigned int qemu_compat_version;
>  static const char *data_dir;
>  const char *bios_name = NULL;
>  enum vga_retrace_method vga_retrace_method = VGA_RETRACE_DUMB;
> @@ -2696,6 +2698,8 @@ int main(int argc, char **argv, char **envp)
>          default_sdcard = 0;
>      }
>  
> +    qemu_compat_version = machine->compat_version;
> +
>      if (display_type == DT_NOGRAPHIC) {
>          if (default_parallel)
>              add_device_config(DEV_PARALLEL, "null");
> -- 
> 1.7.0.4

Looks fine to me, given CPUs are not in qdev. Anthony?
Anthony Liguori - Oct. 6, 2010, 7:24 p.m.
On 10/06/2010 01:53 PM, Marcelo Tosatti wrote:
> On Mon, Sep 27, 2010 at 03:16:15PM +0200, Joerg Roedel wrote:
>    
>> As requested by Alex this patch makes kvm64 the default CPU
>> model when qemu is started with -enable-kvm. This takes only
>> effect for qemu-versions newer or equal to 0.14.0.
>>
>> Signed-off-by: Joerg Roedel<joerg.roedel@amd.com>
>> ---
>>   hw/boards.h    |    1 +
>>   hw/pc.c        |   21 ++++++++++++++++-----
>>   hw/pc_piix.c   |    6 ++++++
>>   qemu-version.h |   35 +++++++++++++++++++++++++++++++++++
>>   vl.c           |    4 ++++
>>   5 files changed, 62 insertions(+), 5 deletions(-)
>>   create mode 100644 qemu-version.h
>>
>> diff --git a/hw/boards.h b/hw/boards.h
>> index 6f0f0d7..2d41b2d 100644
>> --- a/hw/boards.h
>> +++ b/hw/boards.h
>> @@ -19,6 +19,7 @@ typedef struct QEMUMachine {
>>       QEMUMachineInitFunc *init;
>>       int use_scsi;
>>       int max_cpus;
>> +    unsigned int compat_version;
>>       unsigned int no_serial:1,
>>           no_parallel:1,
>>           use_virtcon:1,
>> diff --git a/hw/pc.c b/hw/pc.c
>> index 69b13bf..372ec4c 100644
>> --- a/hw/pc.c
>> +++ b/hw/pc.c
>> @@ -40,6 +40,16 @@
>>   #include "sysbus.h"
>>   #include "sysemu.h"
>>   #include "blockdev.h"
>> +#include "kvm.h"
>> +#include "qemu-version.h"
>> +
>> +#ifdef TARGET_X86_64
>> +#define DEFAULT_KVM_CPU_MODEL "kvm64"
>> +#define DEFAULT_QEMU_CPU_MODEL "qemu64"
>> +#else
>> +#define DEFAULT_KVM_CPU_MODEL "kvm32"
>> +#define DEFAULT_QEMU_CPU_MODEL "qemu32"
>> +#endif
>>
>>   /* output Bochs bios info messages */
>>   //#define DEBUG_BIOS
>> @@ -867,11 +877,12 @@ void pc_cpus_init(const char *cpu_model)
>>
>>       /* init CPUs */
>>       if (cpu_model == NULL) {
>> -#ifdef TARGET_X86_64
>> -        cpu_model = "qemu64";
>> -#else
>> -        cpu_model = "qemu32";
>> -#endif
>> +        if (kvm_enabled()&&
>> +            qemu_compat_version>= QEMU_COMPAT_VERSION(0, 14, 0)) {
>> +            cpu_model = DEFAULT_KVM_CPU_MODEL;
>> +        } else {
>> +            cpu_model = DEFAULT_QEMU_CPU_MODEL;
>> +        }
>>       }
>>
>>       for(i = 0; i<  smp_cpus; i++) {
>> diff --git a/hw/pc_piix.c b/hw/pc_piix.c
>> index 12359a7..9e46b71 100644
>> --- a/hw/pc_piix.c
>> +++ b/hw/pc_piix.c
>> @@ -35,6 +35,7 @@
>>   #include "sysemu.h"
>>   #include "sysbus.h"
>>   #include "blockdev.h"
>> +#include "qemu-version.h"
>>
>>   #define MAX_IDE_BUS 2
>>
>> @@ -217,6 +218,7 @@ static QEMUMachine pc_machine = {
>>       .desc = "Standard PC",
>>       .init = pc_init_pci,
>>       .max_cpus = 255,
>> +    .compat_version = QEMU_COMPAT_VERSION(0, 13, 0),
>>       .is_default = 1,
>>   };
>>
>> @@ -225,6 +227,7 @@ static QEMUMachine pc_machine_v0_12 = {
>>       .desc = "Standard PC",
>>       .init = pc_init_pci,
>>       .max_cpus = 255,
>> +    .compat_version = QEMU_COMPAT_VERSION(0, 12, 0),
>>       .compat_props = (GlobalProperty[]) {
>>           {
>>               .driver   = "virtio-serial-pci",
>> @@ -244,6 +247,7 @@ static QEMUMachine pc_machine_v0_11 = {
>>       .desc = "Standard PC, qemu 0.11",
>>       .init = pc_init_pci,
>>       .max_cpus = 255,
>> +    .compat_version = QEMU_COMPAT_VERSION(0, 11, 0),
>>       .compat_props = (GlobalProperty[]) {
>>           {
>>               .driver   = "virtio-blk-pci",
>> @@ -279,6 +283,7 @@ static QEMUMachine pc_machine_v0_10 = {
>>       .desc = "Standard PC, qemu 0.10",
>>       .init = pc_init_pci,
>>       .max_cpus = 255,
>> +    .compat_version = QEMU_COMPAT_VERSION(0, 10, 0),
>>       .compat_props = (GlobalProperty[]) {
>>           {
>>               .driver   = "virtio-blk-pci",
>> @@ -325,6 +330,7 @@ static QEMUMachine isapc_machine = {
>>       .name = "isapc",
>>       .desc = "ISA-only PC",
>>       .init = pc_init_isa,
>> +    .compat_version = QEMU_COMPAT_VERSION(0, 10, 0),
>>       .max_cpus = 1,
>>   };
>>
>> diff --git a/qemu-version.h b/qemu-version.h
>> new file mode 100644
>> index 0000000..b4bfe48
>> --- /dev/null
>> +++ b/qemu-version.h
>> @@ -0,0 +1,35 @@
>> +/*
>> + * qemu-version.h
>> + *
>> + * Defines needed for handling QEMU version compatibility
>> + *
>> + * Copyright (c) 2010 Joerg Roedel<joerg.roedel@amd.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 _QEMU_VERSION_H_
>> +#define _QEMU_VERSION_H_
>> +
>> +extern unsigned int qemu_compat_version;
>> +
>> +#define QEMU_COMPAT_VERSION(major, minor, patchlevel) \
>> +        ((unsigned int)(major<<  16) | (minor<<  8) | (patchlevel))
>> +
>> +#endif
>> diff --git a/vl.c b/vl.c
>> index d352d18..37727f3 100644
>> --- a/vl.c
>> +++ b/vl.c
>> @@ -161,6 +161,7 @@ int main(int argc, char **argv)
>>   #include "qemu-queue.h"
>>   #include "cpus.h"
>>   #include "arch_init.h"
>> +#include "qemu-version.h"
>>
>>   //#define DEBUG_NET
>>   //#define DEBUG_SLIRP
>> @@ -169,6 +170,7 @@ int main(int argc, char **argv)
>>
>>   #define MAX_VIRTIO_CONSOLES 1
>>
>> +unsigned int qemu_compat_version;
>>   static const char *data_dir;
>>   const char *bios_name = NULL;
>>   enum vga_retrace_method vga_retrace_method = VGA_RETRACE_DUMB;
>> @@ -2696,6 +2698,8 @@ int main(int argc, char **argv, char **envp)
>>           default_sdcard = 0;
>>       }
>>
>> +    qemu_compat_version = machine->compat_version;
>> +
>>       if (display_type == DT_NOGRAPHIC) {
>>           if (default_parallel)
>>               add_device_config(DEV_PARALLEL, "null");
>> -- 
>> 1.7.0.4
>>      
> Looks fine to me, given CPUs are not in qdev. Anthony?
>    

The idea is fine, but why not just add the default CPU to the machine 
description?

Regards,

Anthony Liguori
Joerg Roedel - Oct. 7, 2010, 8:42 a.m.
On Wed, Oct 06, 2010 at 03:24:59PM -0400, Anthony Liguori wrote:
> >> +    qemu_compat_version = machine->compat_version;
> >> +
> >>       if (display_type == DT_NOGRAPHIC) {
> >>           if (default_parallel)
> >>               add_device_config(DEV_PARALLEL, "null");
> >> -- 
> >> 1.7.0.4
> >>      
> > Looks fine to me, given CPUs are not in qdev. Anthony?
> >    
> 
> The idea is fine, but why not just add the default CPU to the machine 
> description?

If I remember correctly the reason was that the machine description was
not accessible in the cpuid initialization path because it is a function
local variable. I could have made it a global variable but considered
the compat_version approach simpler. The qemu_compat_version might also
be useful at other places.

	Joerg

Patch

diff --git a/hw/boards.h b/hw/boards.h
index 6f0f0d7..2d41b2d 100644
--- a/hw/boards.h
+++ b/hw/boards.h
@@ -19,6 +19,7 @@  typedef struct QEMUMachine {
     QEMUMachineInitFunc *init;
     int use_scsi;
     int max_cpus;
+    unsigned int compat_version;
     unsigned int no_serial:1,
         no_parallel:1,
         use_virtcon:1,
diff --git a/hw/pc.c b/hw/pc.c
index 69b13bf..372ec4c 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -40,6 +40,16 @@ 
 #include "sysbus.h"
 #include "sysemu.h"
 #include "blockdev.h"
+#include "kvm.h"
+#include "qemu-version.h"
+
+#ifdef TARGET_X86_64
+#define DEFAULT_KVM_CPU_MODEL "kvm64"
+#define DEFAULT_QEMU_CPU_MODEL "qemu64"
+#else
+#define DEFAULT_KVM_CPU_MODEL "kvm32"
+#define DEFAULT_QEMU_CPU_MODEL "qemu32"
+#endif
 
 /* output Bochs bios info messages */
 //#define DEBUG_BIOS
@@ -867,11 +877,12 @@  void pc_cpus_init(const char *cpu_model)
 
     /* init CPUs */
     if (cpu_model == NULL) {
-#ifdef TARGET_X86_64
-        cpu_model = "qemu64";
-#else
-        cpu_model = "qemu32";
-#endif
+        if (kvm_enabled() &&
+            qemu_compat_version >= QEMU_COMPAT_VERSION(0, 14, 0)) {
+            cpu_model = DEFAULT_KVM_CPU_MODEL;
+        } else {
+            cpu_model = DEFAULT_QEMU_CPU_MODEL;
+        }
     }
 
     for(i = 0; i < smp_cpus; i++) {
diff --git a/hw/pc_piix.c b/hw/pc_piix.c
index 12359a7..9e46b71 100644
--- a/hw/pc_piix.c
+++ b/hw/pc_piix.c
@@ -35,6 +35,7 @@ 
 #include "sysemu.h"
 #include "sysbus.h"
 #include "blockdev.h"
+#include "qemu-version.h"
 
 #define MAX_IDE_BUS 2
 
@@ -217,6 +218,7 @@  static QEMUMachine pc_machine = {
     .desc = "Standard PC",
     .init = pc_init_pci,
     .max_cpus = 255,
+    .compat_version = QEMU_COMPAT_VERSION(0, 13, 0),
     .is_default = 1,
 };
 
@@ -225,6 +227,7 @@  static QEMUMachine pc_machine_v0_12 = {
     .desc = "Standard PC",
     .init = pc_init_pci,
     .max_cpus = 255,
+    .compat_version = QEMU_COMPAT_VERSION(0, 12, 0),
     .compat_props = (GlobalProperty[]) {
         {
             .driver   = "virtio-serial-pci",
@@ -244,6 +247,7 @@  static QEMUMachine pc_machine_v0_11 = {
     .desc = "Standard PC, qemu 0.11",
     .init = pc_init_pci,
     .max_cpus = 255,
+    .compat_version = QEMU_COMPAT_VERSION(0, 11, 0),
     .compat_props = (GlobalProperty[]) {
         {
             .driver   = "virtio-blk-pci",
@@ -279,6 +283,7 @@  static QEMUMachine pc_machine_v0_10 = {
     .desc = "Standard PC, qemu 0.10",
     .init = pc_init_pci,
     .max_cpus = 255,
+    .compat_version = QEMU_COMPAT_VERSION(0, 10, 0),
     .compat_props = (GlobalProperty[]) {
         {
             .driver   = "virtio-blk-pci",
@@ -325,6 +330,7 @@  static QEMUMachine isapc_machine = {
     .name = "isapc",
     .desc = "ISA-only PC",
     .init = pc_init_isa,
+    .compat_version = QEMU_COMPAT_VERSION(0, 10, 0),
     .max_cpus = 1,
 };
 
diff --git a/qemu-version.h b/qemu-version.h
new file mode 100644
index 0000000..b4bfe48
--- /dev/null
+++ b/qemu-version.h
@@ -0,0 +1,35 @@ 
+/*
+ * qemu-version.h
+ *
+ * Defines needed for handling QEMU version compatibility
+ *
+ * Copyright (c) 2010 Joerg Roedel <joerg.roedel@amd.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 _QEMU_VERSION_H_
+#define _QEMU_VERSION_H_
+
+extern unsigned int qemu_compat_version;
+
+#define QEMU_COMPAT_VERSION(major, minor, patchlevel) \
+        ((unsigned int)(major << 16) | (minor << 8) | (patchlevel))
+
+#endif
diff --git a/vl.c b/vl.c
index d352d18..37727f3 100644
--- a/vl.c
+++ b/vl.c
@@ -161,6 +161,7 @@  int main(int argc, char **argv)
 #include "qemu-queue.h"
 #include "cpus.h"
 #include "arch_init.h"
+#include "qemu-version.h"
 
 //#define DEBUG_NET
 //#define DEBUG_SLIRP
@@ -169,6 +170,7 @@  int main(int argc, char **argv)
 
 #define MAX_VIRTIO_CONSOLES 1
 
+unsigned int qemu_compat_version;
 static const char *data_dir;
 const char *bios_name = NULL;
 enum vga_retrace_method vga_retrace_method = VGA_RETRACE_DUMB;
@@ -2696,6 +2698,8 @@  int main(int argc, char **argv, char **envp)
         default_sdcard = 0;
     }
 
+    qemu_compat_version = machine->compat_version;
+
     if (display_type == DT_NOGRAPHIC) {
         if (default_parallel)
             add_device_config(DEV_PARALLEL, "null");