Re: [PATCH 2/3] Fix CPU hotplug

[Gleb Natapov <gleb@redhat.com>]

On Wed, Feb 04, 2009 at 02:45:12PM +0200, Avi Kivity wrote:
> Gleb Natapov wrote:
>> 1) Disabled processor's _STA method should return 0 (this fixes Vista's
>>    BSOD on resuming after hibernate problem)
>> 2) Disabled processor's _MAT method should return disabled MADT entry
>>    instead of 0
>> 3) Extend bitmask of hot pluggable CPUs to be 16 bit long
>> 4) Generate interrupt only if corespondent EN bit is set
>>   
>
> Looks like a good idea, but it is really necessary?  The guest should be  
> able to deal with null notifies.
> (I'd like to apply this, just want to understand).
>
I don't really know what different OSes will do with null notifiers. But
if one of them will not handle them properly I don't want to be the one
who'll debug it :)
 
>> --- a/qemu/hw/acpi.c
>> +++ b/qemu/hw/acpi.c
>> @@ -578,8 +578,8 @@ void qemu_system_powerdown(void)
>>  struct gpe_regs {
>>      uint16_t sts; /* status */
>>      uint16_t en;  /* enabled */
>> -    uint8_t up;
>> -    uint8_t down;
>> +    uint16_t cpus_sts;
>> +    uint16_t bios_cpus_sts;
>>  };
>>   
>
> We'll need to scale this soon.
>
We should think how to handle Windows 2000 15 CPU limit.

>>   struct pci_status {
>> @@ -603,10 +603,12 @@ static uint32_t gpe_readb(void *opaque, uint32_t addr)
>>      struct gpe_regs *g = opaque;
>>      switch (addr) {
>>          case PROC_BASE:
>> -            val = g->up;
>> -            break;
>>          case PROC_BASE + 1:
>> -            val = g->down;
>> +            val = gpe_read_val(g->cpus_sts, addr);
>> +            break;
>> +        case PROC_BASE + 2:
>> +        case PROC_BASE + 3:
>> +            val = gpe_read_val(g->bios_cpus_sts, addr);
>>              break;
>>   
>
> Why can't the bios maintain bios_cpu_sts in RAM?
>
It can, just need to find a place for it. Currently our AML does not use
RAM at all.

--
			Gleb.