Re: [Qemu-devel] [PATCH 2/2] i386: Add a Virtual Machine Generation ID device.

[Markus Armbruster <armbru@redhat.com>]

Paolo Bonzini <pbonzini@redhat.com> writes:

> Il 12/08/2014 10:02, Gal Hammer ha scritto:
>> Hi,
>> 
>> On 10/08/2014 20:22, Paolo Bonzini wrote:
>> 
>>> Il 10/08/2014 13:32, Gal Hammer ha scritto:
>>>> Based on Microsoft's sepecifications (paper can be dowloaded from
>>>> http://go.microsoft.com/fwlink/?LinkId=260709), add a device
>>>> description to the SSDT ACPI table.
>>>>
>>>> The GUID is set using a new "-vmgenid" command line parameter.
>>>>
>>>> Signed-off-by: Gal Hammer <ghammer@redhat.com>
>>>> ---
>>>>   hw/i386/acpi-build.c  | 23 +++++++++++++++++++++++
>>>>   hw/i386/ssdt-misc.dsl | 33 +++++++++++++++++++++++++++++++++
>>>>   qemu-options.hx       |  9 +++++++++
>>>>   vl.c                  | 11 +++++++++++
>>>>   4 files changed, 76 insertions(+)
>>>
>>> Please make this a new device (like pvpanic), instead of adding a new
>>> command-line option.
>> 
>> There is a problem with this request. I don't want to use ISA because it
>> is obsolete, PCI is overkill for such a device and a SYSBUS (like HPET)
>> device doesn't effect the command line options.
>> 
>> Did I miss something in SYSBUS and that's was the reason it didn't
>> appear in the "-device ?" list?
>
> For a sysbus device, you can override the
> cannot_instantiate_with_device_add_yet field of DeviceClass in your
> class_init function.

Correct.

Sysbus devices are not available with device_add / -device by default,
because to actually work, they commonly require code to connect them to
other devices.  A sysbus device that doesn't need such connections can
be made available with device_add / -device in the way Paolo described.

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