Re: [Qemu-devel] [RESEND PATCH v3] hotplug: add device per func in ACPI DSDT tables

[Jiang Liu <liuj97@gmail.com>]

On 05/11/2012 01:42 AM, Michael S. Tsirkin wrote:
> On Fri, May 11, 2012 at 01:17:38AM +0800, Jiang Liu wrote:
>> On 05/09/2012 03:24 PM, Amos Kong wrote:
>>
>>> ---
>>>  src/ssdt-pcihp.dsl |   17 
>>>  src/ssdt-pcihp.hex | 8869 +++++++++++++++++++++++++++++++++++++++++++++++++++-
>>>  2 files changed, 8781 insertions(+), 105 deletions(-)
>>>
>>> diff --git a/src/ssdt-pcihp.dsl b/src/ssdt-pcihp.dsl
>>> index 4b435b8..2a3c326 100644
>>> --- a/src/ssdt-pcihp.dsl
>>> +++ b/src/ssdt-pcihp.dsl
>>> @@ -17,14 +17,23 @@ DefinitionBlock ("ssdt-pcihp.aml", "SSDT", 0x01, "BXPC", "BXSSDTPCIHP", 0x1)
>>>          // at runtime, if the slot is detected to not support hotplug.
>>>          // Extract the offset of the address dword and the
>>>          // _EJ0 name to allow this patching.
>>> -#define hotplug_slot(slot)                              \
>>> -        Device (S##slot) {                              \
>>> +#define hotplug_func(slot, fn)                          \
>>> +        Device (S##slot##fn) {                          \
>>>             ACPI_EXTRACT_NAME_DWORD_CONST aml_adr_dword  \
>>> -           Name (_ADR, 0x##slot##0000)                  \
>>> +           Name (_ADR, 0x##slot##000##fn)               \
>>>             ACPI_EXTRACT_METHOD_STRING aml_ej0_name      \
>>>             Method (_EJ0, 1) { Return(PCEJ(0x##slot)) }  \
>>>             Name (_SUN, 0x##slot)                        \
>>>          }
>> It would be perfect if the Device object could also support _PS0 and _STA
>> methods.
> 
> It needs qemu support, and some backward compatibility hack.
> Why?
> 
>> Could we re-add the slot back after hot-removing it from the guest
>> OS with this ACPI implementation? Say execute following scripts from guest OS.
>> echo 0 > /sys/bus/pci/slot/xx/power
>> echo 1 > /sys/bus/pci/slot/xx/power
> 
> No because qemu removes device after eject.
> Do you have a need for this functionality? What is it?

I'm not familiar with qemu:(
On native OS, admin could trigger PCI device hotplug operations through
/sys/bus/pci/slot/xx/power. Not sure whether that's needed for guest OS too.