Re: [dpdk-dev] [PATCH] app/testpmd: send failure logs to stderr

[Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>]

On 6/11/21 1:35 PM, Ferruh Yigit wrote:
> On 6/11/2021 10:19 AM, Andrew Rybchenko wrote:
>> On 6/11/21 5:06 AM, Li, Xiaoyun wrote:
>>> Hi
>>> -----Original Message-----
>>> From: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
>>> Sent: Friday, May 28, 2021 00:25
>>> To: Li, Xiaoyun <xiaoyun.li@intel.com>
>>> Cc: dev@dpdk.org
>>> Subject: [PATCH] app/testpmd: send failure logs to stderr
>>>
>>> Running with stdout suppressed or redirected for further processing is very confusing in the case of errors.
>>>
>>> Signed-off-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
>>> ---
>>>
>>> This patch looks good to me.
>>> But what do you think about make it as a fix and backport to stable branches?
>>> Anyway works for me.
>>
>> I have no strong opinion on the topic.
>>
>> @Ferruh, what do you think?
>>
> 
> Same here, no strong opinion.
> Sending errors to 'stderr' looks correct thing to do, but changing behavior in
> the LTS may cause some unexpected side affect, if it is scripted and testpmd
> output is parsed etc... For this possibility I would wait for the next LTS.

So, I guess all agree that backporting to LTS is a bad idea because of
behaviour change.

As I said in a sub-thread I tend to apply in v21.08 since it is a right
thing to do like a fix, but the fix is not that required to be
backported to change behaviour of LTS releases.

> And because of same reason perhaps a release note can be added.

I'll make v2 with release notes added. Good point.

> Also there is 'TESTPMD_LOG' macro for logs in testpmd, (as well as 'RTE_LOG'
> macro), I don't know if we should switch all logs, including 'printf', to
> 'TESTPMD_LOG' macro?
> Later stdout/sderr can be managed in rte_log level, instead of any specific
> logic for the testpmd.

I think fprintf() is a better option for debug tool, since its
messages should not go to syslog etc. It should go to stdout/stderr
regardless of logging configuration and log level settings.

> Even there was a defect for this in the rte_log level, that logs should go to
> stderr: https://bugs.dpdk.org/show_bug.cgi?id=8
> 
> 
>>> Acked-by: Xiaoyun Li <xiaoyun.li@intel.com>
>>