[dpdk-dev] [PATCH v10 05/11] net/failsafe: add flexible device definition

[Ferruh Yigit]

On 7/17/2017 4:52 PM, Gaëtan Rivet wrote:
> Hi Ferruh,
> 
> (Thanks for the review by the way, I will answer the other more lengthy
> emails in due time)
> 
> On Mon, Jul 17, 2017 at 04:45:59PM +0100, Ferruh Yigit wrote:
>> On 7/15/2017 6:57 PM, Gaetan Rivet wrote:
>>> Add the "exec" device type.
>>> The parameters given to this type of device will be executed in a shell.
>>> The output of this command is then used as a definition for a device.
>>>
>>> That command can be re-interpreted if the related device is not
>>> plugged-in. It allows for a device definition to react to system
>>> changes (e.g. changing PCI bus for a given device).
>>>
>>> Signed-off-by: Gaetan Rivet <gaetan.rivet at 6wind.com>
>>> Acked-by: Olga Shern <olgas at mellanox.com>
>>> ---
>>>  doc/guides/nics/fail_safe.rst           | 20 +++++++
>>>  drivers/net/failsafe/failsafe_args.c    | 95 +++++++++++++++++++++++++++++++++
>>>  drivers/net/failsafe/failsafe_ether.c   |  7 +++
>>>  drivers/net/failsafe/failsafe_private.h |  4 ++
>>>  4 files changed, 126 insertions(+)
>>>
>>> diff --git a/doc/guides/nics/fail_safe.rst b/doc/guides/nics/fail_safe.rst
>>> index 5ec3031..be73d7e 100644
>>> --- a/doc/guides/nics/fail_safe.rst
>>> +++ b/doc/guides/nics/fail_safe.rst
>>> @@ -87,6 +87,19 @@ Fail-safe command line parameters
>>>    additional sub-device parameters if need be. They will be passed on to the
>>>    sub-device.
>>>  
>>> +- **exec(<shell command>)** parameter
>>> +
>>> +  This parameter allows the user to provide a command to the fail-safe PMD to
>>> +  execute and define a sub-device.
>>> +  It is done within a regular shell context.
>>> +  The first line of its output is read by the fail-safe PMD and otherwise
>>> +  interpreted as if passed by the regular **dev** parameter.
>>> +  Any other line is discarded.
>>> +  If the command fail or output an incorrect string, the sub-device is not
>>> +  initialized.
>>> +  All commas within the ``shell command`` are replaced by spaces before
>>> +  executing the command. This helps using scripts to specify devices.
>>> +
>>>  - **mac** parameter [MAC address]
>>>  
>>>    This parameter allows the user to set a default MAC address to the fail-safe
>>> @@ -135,6 +148,13 @@ This section shows some example of using **testpmd** with a fail-safe PMD.
>>>           -w 'net_failsafe0,mac=de:ad:be:ef:01:02,dev(84:00.0),dev(net_ring0)'
>>>           -w 81:00.0 -- -i
>>>  
>>> +#. Start testpmd using a flexible device definition
>>> +
>>> +   .. code-block:: console
>>> +
>>> +      $RTE_TARGET/build/app/testpmd -c 0xff -n 4 --no-pci \
>>> +         --vdev='net_failsafe0,exec(echo 84:00.0)' -- -i
>>
>> Hi Gaetan,
>>
>> What is the usecase for this feature.
>>
>> How this is different from --vdev='net_failsafe0,dev(`echo 84:00.0`)' ?
> 
> This version would be interpreted once, at the launch of the fail-safe
> PMD.
> 
> The exec option will execute the command again each time the fail-safe
> tries to probe the sub_device. This means that in a live VM migration
> context, the sub_device can change PCI address (for example), and still be
> matched by the command using other identifying info (MAC address,
> class_id, ...).
> 
> It must be reinterpreted upon plugin of the sub_device,
> as the output would change from the time the fail-safe was started.

Make sense, thanks for clarification.