Re: [Qemu-devel] [PATCH v3 26/32] nvdimm: save arg3 for NVDIMM device _DSM method

[Xiao Guangrong <guangrong.xiao@linux.intel.com>]

On 10/19/2015 02:50 PM, Michael S. Tsirkin wrote:
> On Sun, Oct 11, 2015 at 11:52:58AM +0800, Xiao Guangrong wrote:
>> Check if the input Arg3 is valid then store it into dsm_in if needed
>>
>> We only do the save on NVDIMM device since we are not going to support any
>> function on root device
>>
>> Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
>> ---
>>   hw/mem/nvdimm/acpi.c | 21 ++++++++++++++++++++-
>>   1 file changed, 20 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/mem/nvdimm/acpi.c b/hw/mem/nvdimm/acpi.c
>> index d9fa0fd..3b9399c 100644
>> --- a/hw/mem/nvdimm/acpi.c
>> +++ b/hw/mem/nvdimm/acpi.c
>> @@ -442,7 +442,7 @@ static void build_nvdimm_devices(NVDIMMState *state, GSList *device_list,
>>           int slot = object_property_get_int(OBJECT(nvdimm), DIMM_SLOT_PROP,
>>                                              NULL);
>>           uint32_t handle = nvdimm_slot_to_handle(slot);
>> -        Aml *dev, *method;
>> +        Aml *dev, *method, *ifctx;
>>
>>           dev = aml_device("NV%02X", slot);
>>           aml_append(dev, aml_name_decl("_ADR", aml_int(handle)));
>> @@ -452,6 +452,24 @@ static void build_nvdimm_devices(NVDIMMState *state, GSList *device_list,
>>           method = aml_method("_DSM", 4);
>>           {
>>               SAVE_ARG012_HANDLE_LOCK(method, aml_int(handle));
>> +
>> +            /* Arg3 is passed as Package and it has one element? */
>> +            ifctx = aml_if(aml_and(aml_equal(aml_object_type(aml_arg(3)),
>> +                                             aml_int(4)),
>> +                                   aml_equal(aml_sizeof(aml_arg(3)),
>
> aml_arg(3) is used many times below.
> Pls give it a name that makes sense (not arg3! what is it for?)
>

Er. aml_arg(3) is just the fourth parameter of _DSM method. Will add some
comments:

/*
  * The fourth parameter (Arg3) of _DMS is a package which contains a buffer, the
  * layout of the buffer is specified by UUID (Arg0), Revision ID (Arg1) and
  * Function Index (Arg2) which are documented in the DSM specification.
  */

>> +                                             aml_int(1))));
>
> Pls document AML constants used.
> Like this:
>
>              ifctx = aml_if(aml_and(aml_equal(aml_object_type(aml_arg(3)),
>                                               aml_int(4 /* 4 - Package */) ),
>                                     aml_equal(aml_sizeof(aml_arg(3)),
>                                               aml_int(1))));
>
>> +            {
>> +                /* Local0 = Index(Arg3, 0) */
>> +                aml_append(ifctx, aml_store(aml_index(aml_arg(3), aml_int(0)),
>> +                                            aml_local(0)));
>> +                /* Local3 = DeRefOf(Local0) */
>> +                aml_append(ifctx, aml_store(aml_derefof(aml_local(0)),
>> +                                            aml_local(3)));
>> +                /* ARG3 = Local3 */
>> +                aml_append(ifctx, aml_store(aml_local(3), aml_name("ARG3")));
>
> This isn't a good way to comment things: you are
> just adding ASL before the equivalent C.
> Pls document what's going on.
>

Okay... i just thought C is little readable than AML. Will change the comment
to:

/* fetch buffer from the package (Arg3) and store it to DSM memory. */

Thanks.