Re: [PATCH net-next V2 7/7] devlink: Add eswitch mode boot defaults

[Mark Bloch]

On 03/06/2026 23:06, Randy Dunlap wrote:
> Hi.
> 
> On 6/3/26 12:32 PM, Mark Bloch wrote:
>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>> index 063c11ca33e5..7af9f2898d92 100644
>> --- a/Documentation/admin-guide/kernel-parameters.txt
>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>> @@ -1264,6 +1264,31 @@ Kernel parameters
>>  	dell_smm_hwmon.fan_max=
>>  			[HW] Maximum configurable fan speed.
>>  
>> +	devlink_eswitch_mode=
>> +			[NET]
>> +			Format:
>> +			[<selector>]:<mode>
> 
> It appears (please correct me if I am mistaken) that the '[' and ']'
> above don't mean "optional" but instead they are required characters...
> 
>> +
>> +			<selector>:
>> +			* | <handle>[,<handle>...]
> 
> while here they mean "optional".
> 
> That is confusing (inconsistent). Also, if the square brackets are
> always required around the <selector>, what purpose do they serve?

Yes, you are right, this is confusing. The outer square brackets are part of
the syntax and are required, while the brackets in "[,<handle>...]" mean that
additional handles are optional.

I couldn't find a better way to describe this. What I want to say is that the
selector is always wrapped in square brackets. Inside the brackets it can either
be "*" to match all devices, or a comma separated list of handles. If "*" is
not used, then at least one handle has to be provided.

Maybe it would be clearer to spell it out explicitly, something like:

Format:
  [<selector>]:<mode>

The '[' and ']' characters are literal and required.

<selector>:
  * | <handle>[,<handle>...]

If '*' is not used, <selector> must contain at least one <handle>.

Does that sound like a reasonable way to document it?

Mark

> 
>> +
>> +			<handle>:
>> +			<bus-name>/<dev-name>
>> +
>> +			Configure default devlink eswitch mode for matching
>> +			devlink instances during device initialization.
>> +
>> +			<mode>:
>> +			legacy | switchdev | switchdev_inactive
>> +
>> +			Examples:
>> +			devlink_eswitch_mode=[*]:switchdev
>> +			devlink_eswitch_mode=[pci/0000:08:00.0]:switchdev
>> +			devlink_eswitch_mode=[pci/0000:08:00.0,pci/0000:09:00.1]:legacy
>> +
>> +			See Documentation/networking/devlink/devlink-defaults.rst
>> +			for the full syntax.
>> +
>>  	dfltcc=		[HW,S390]
>>  			Format: { on | off | def_only | inf_only | always }
>>  			on:       s390 zlib hardware support for compression on
> 
>