Re: [Qemu-devel] [PATCH] acpi-build: Set FORCE_APIC_CLUSTER_MODEL bit of FADT flags

[zhanghailiang <zhang.zhanghailiang@huawei.com>]

On 2014/8/27 21:59, Michael S. Tsirkin wrote:
> On Thu, Aug 21, 2014 at 04:37:29PM +0800, zhanghailiang wrote:
>> If we start Windows 2008 R2 DataCenter with number of cpu less than 8,
>> The system will use APIC Flat Logical destination mode as default configuration,
>> Which has an upper limit of 8 CPUs.
>>
>> The fault is that VM can not show all processors within Task Manager if
>> we hot-add cpus when the number of cpus in VM extends the limit of 8.
>>
>> If we use cluster destination model, the problem will be solved.
>>
>> Signed-off-by: huangzhichao<huangzhichao@huawei.com>
>> Signed-off-by: zhanghailiang<zhang.zhanghailiang@huawei.com>
>
> What if maxcpus is low?
> No reason to force cluster model then, right?
>
Hi Michael,

Yes, It is better not to force cluster model when maxcpus is less than 8.

Can we set this bit according to the value of max_cpus?
Anyway, i think it is a bug;)

What's your suggestion? Thanks.

Best Regards,
zhanghailiang

>> ---
>>   hw/i386/acpi-build.c | 3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
>> index 10b84d0..fed4501 100644
>> --- a/hw/i386/acpi-build.c
>> +++ b/hw/i386/acpi-build.c
>> @@ -545,7 +545,8 @@ static void fadt_setup(AcpiFadtDescriptorRev1 *fadt, AcpiPmInfo *pm)
>>                                 (1<<  ACPI_FADT_F_PROC_C1) |
>>                                 (1<<  ACPI_FADT_F_SLP_BUTTON) |
>>                                 (1<<  ACPI_FADT_F_RTC_S4));
>> -    fadt->flags |= cpu_to_le32(1<<  ACPI_FADT_F_USE_PLATFORM_CLOCK);
>> +    fadt->flags |= cpu_to_le32(1<<  ACPI_FADT_F_USE_PLATFORM_CLOCK |
>> +                               1<<  ACPI_FADT_F_FORCE_APIC_CLUSTER_MODEL);
>>   }
>>
>>
>> --
>> 1.7.12.4
>>
>
> .
>