Re: [Qemu-devel] [PATCH] spapr: add ibm, chip-id property in device tree

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 04/12/2014 02:29 AM, Alexander Graf wrote:
> 
> On 13.03.14 07:29, Alexey Kardashevskiy wrote:
>> This adds a "ibm,chip-id" property for CPU nodes which should be the same
>> for all cores in the same CPU socket. The recent guest kernels use this
>> information to associate threads with sockets.
>>
>> Refer to the kernel commit 256f2d4b463d3030ebc8d2b54f427543814a2bdc
>> for more details.
>>
>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>> ---
>>   hw/ppc/spapr.c | 9 +++++++++
>>   1 file changed, 9 insertions(+)
>>
>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
>> index bf46c38..6366230 100644
>> --- a/hw/ppc/spapr.c
>> +++ b/hw/ppc/spapr.c
>> @@ -308,6 +308,8 @@ static void *spapr_create_fdt_skel(hwaddr initrd_base,
>>       uint32_t interrupt_server_ranges_prop[] = {0, cpu_to_be32(smp_cpus)};
>>       int i, smt = kvmppc_smt_threads();
>>       unsigned char vec5[] = {0x0, 0x0, 0x0, 0x0, 0x0, 0x80};
>> +    QemuOpts *opts = qemu_opts_find(qemu_find_opts("smp-opts"), NULL);
>> +    unsigned sockets = opts ? qemu_opt_get_number(opts, "sockets", 0) : 0;
>>         fdt = g_malloc0(FDT_MAX_SIZE);
>>       _FDT((fdt_create(fdt, FDT_MAX_SIZE)));
>> @@ -465,6 +467,13 @@ static void *spapr_create_fdt_skel(hwaddr initrd_base,
>>                                  page_sizes_prop, page_sizes_prop_size)));
>>           }
>>   +        if (sockets) {
>> +            int cpus_per_socket = smp_cpus / sockets;
>> +            uint32_t chip_id = cs->cpu_index / cpus_per_socket;
>> +
>> +            _FDT((fdt_property_cell(fdt, "ibm,chip-id", chip_id)));
>> +        }
> 
> Have you verified this works correctly with threads? 

Sorry, do not follow you.
-smp X,sockets=Y,threads=Z - what combination of XYZ is suspicious?


> Also, I don't see why
> we should omit the chip-id when we don't define sockets.

Why should we pollute device tree...



-- 
Alexey