Re: [PATCH v2] net/tap: resolve stringop-overflow with gcc 12 on ppc64le

[Ferruh Yigit <ferruh.yigit@amd.com>]

On 5/16/2023 12:20 AM, Stephen Hemminger wrote:
> On Tue, 16 May 2023 00:14:52 +0100
> Ferruh Yigit <ferruh.yigit@amd.com> wrote:
> 
>> Hi David,
>>
>> I confirm the build error, btw it helps to future references to put
>> build failure to the commit log,
>>
>> and change is reasonable to convert PMD local parse function to an API,
>> BUT my concern is they don't behave exactly same, which changes user
>> interface of the driver.
>>
>> The 'rte_ether_unformat_addr()' API expects exact "XX:XX:XX:XX:XX:XX or
>> XXXX:XXXX:XXXX" format.
>> Like 'parse_user_mac()' accepts 'a:a:a:a:a:a' as input, but API requires
>> '0A:0A:0A:0A:0A:0A'.
>>
>> This is a small change but still may create a bad experience if an
>> existing user/script hit by this, and I believe we don't have a strong
>> reason to change the interface.
>>
>>
>> To keep behavior same, we can either update 'rte_ether_unformat_addr()'
>> to accept singe chars between ':',
>> or fix the existing 'parse_user_mac()' for compiler warning, what do you
>> think?
> 
> This is the kind of change where a simple release note will suffice.
> 
> Not sure if anyone beyond some test script would ever use this anyway.


Yes only some scripts and possible applications that hotplug tap
interface with hardcoded parameters may impacted, don't know how big is
this amount but this ends up breaking something that was working before
upgrading DPDK for them.

And I believe the motivation is weak to break the behavior.

Won't it be better to update 'rte_ether_unformat_addr()' to accept more
flexible syntax, and use it? Is there any disadvantage of this approach?