[dpdk-dev] [PATCH v5 02/10] eal: add power management intrinsics

[Burakov, Anatoly]

On 09-Oct-20 5:09 PM, Jerin Jacob wrote:
> On Fri, Oct 9, 2020 at 9:32 PM Anatoly Burakov
> <anatoly.burakov at intel.com> wrote:
>>
>> From: Liang Ma <liang.j.ma at intel.com>
>>
>> Add two new power management intrinsics, and provide an implementation
>> in eal/x86 based on UMONITOR/UMWAIT instructions. The instructions
>> are implemented as raw byte opcodes because there is not yet widespread
>> compiler support for these instructions.
>>
>> The power management instructions provide an architecture-specific
>> function to either wait until a specified TSC timestamp is reached, or
>> optionally wait until either a TSC timestamp is reached or a memory
>> location is written to. The monitor function also provides an optional
>> comparison, to avoid sleeping when the expected write has already
>> happened, and no more writes are expected.
>>
>> For more details, please refer to Intel(R) 64 and IA-32 Architectures
>> Software Developer's Manual, Volume 2.
>>
>> Signed-off-by: Liang Ma <liang.j.ma at intel.com>
>> Signed-off-by: Anatoly Burakov <anatoly.burakov at intel.com>
>> ---
>>
>> Notes:
>>      v5:
>>      - Removed return values
>>      - Simplified intrinsics and hardcoded C0.2 state
>>      - Added other arch stubs

<snip>

>> +
>> +/**
>> + * This function is not supported on ARM.
>> + *
>> + * @param p
>> + *   Address to monitor for changes. Must be aligned on an 64-byte boundary.
>> + * @param expected_value
>> + *   Before attempting the monitoring, the `p` address may be read and compared
>> + *   against this value. If `value_mask` is zero, this step will be skipped.
>> + * @param value_mask
>> + *   The 64-bit mask to use to extract current value from `p`.
>> + * @param tsc_timestamp
>> + *   Maximum TSC timestamp to wait for.
>> + *
>> + * @return
>> + *   - 0 on success
> 
> 
> remove return as it is a void function

Oops, will fix in v6. Thanks!

-- 
Thanks,
Anatoly