Re: [Qemu-devel] [PATCH] xen: make xen-platform a default device

[Paolo Bonzini <pbonzini@redhat.com>]

Il 22/05/2014 14:11, Stefano Stabellini ha scritto:
> On Thu, 22 May 2014, Gerd Hoffmann wrote:
>> Patch hooks up the xen platform device to the default device code we
>> have in qemu.  Two effects:
>>
>>   (1) The device will not be created in case -nodefaults is specified
>>       on the command line.
>>   (2) Autocreating the device is also turned off in case xen-platform
>>       is added manually via -device.
>>
>> With the patch applied you can move the xen-platform device to some
>> other place with a simple 'qemu -device xen-platform,addr=$slot'.
>>
>> Tested-by: Tiejun Chen <tiejun.chen@intel.com>
>> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
>
> Given that libxl always passes -nodefaults to QEMU, this patch is going
> to effectively disable xen_platform_pci for all Xen users. It is not a
> good idea. With the patch applied a Xen user would have no way to enable
> xen_platform_pci except for passing some magic command line runes via
> device_model_args_hvm.

In fact this code only runs for "-M xenfv".  If you use "-M pc", the 
xen-platform device has to be added manually.  Perhaps it would be 
worthwhile to do the opposite, i.e. add the xen-platform device to "-M 
pc" if not using -nodefaults.

Paolo

>
>>  hw/i386/pc_piix.c    | 2 +-
>>  include/hw/xen/xen.h | 1 +
>>  vl.c                 | 3 +++
>>  3 files changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
>> index eaf3e61..f987d03 100644
>> --- a/hw/i386/pc_piix.c
>> +++ b/hw/i386/pc_piix.c
>> @@ -385,7 +385,7 @@ static void pc_xen_hvm_init(QEMUMachineInitArgs *args)
>>      pc_init_pci(args);
>>
>>      bus = pci_find_primary_bus();
>> -    if (bus != NULL) {
>> +    if (bus != NULL && default_xenplatform) {
>>          pci_create_simple(bus, -1, "xen-platform");
>>      }
>>  }
>> diff --git a/include/hw/xen/xen.h b/include/hw/xen/xen.h
>> index 85fda3d..b350413 100644
>> --- a/include/hw/xen/xen.h
>> +++ b/include/hw/xen/xen.h
>> @@ -20,6 +20,7 @@ enum xen_mode {
>>
>>  extern uint32_t xen_domid;
>>  extern enum xen_mode xen_mode;
>> +extern int default_xenplatform;
>>
>>  extern bool xen_allowed;
>>
>> diff --git a/vl.c b/vl.c
>> index 709d8cd..673148e 100644
>> --- a/vl.c
>> +++ b/vl.c
>> @@ -226,6 +226,7 @@ static int default_floppy = 1;
>>  static int default_cdrom = 1;
>>  static int default_sdcard = 1;
>>  static int default_vga = 1;
>> +int default_xenplatform = 1;
>>
>>  static struct {
>>      const char *driver;
>> @@ -247,6 +248,7 @@ static struct {
>>      { .driver = "isa-cirrus-vga",       .flag = &default_vga       },
>>      { .driver = "vmware-svga",          .flag = &default_vga       },
>>      { .driver = "qxl-vga",              .flag = &default_vga       },
>> +    { .driver = "xen-platform",         .flag = &default_xenplatform },
>>  };
>>
>>  static QemuOptsList qemu_rtc_opts = {
>> @@ -4101,6 +4103,7 @@ int main(int argc, char **argv, char **envp)
>>          default_monitor = 0;
>>          default_net = 0;
>>          default_vga = 0;
>> +        default_xenplatform = 0;
>>      }
>>
>>      if (is_daemonized()) {
>> --
>> 1.8.3.1
>>
>>
>
>