[dpdk-dev] Windows: A fundamental issue (was eal/windows: definition for ETOOMANYREFS errno)

[Nick Connolly]

Thanks Tal.


On 19/11/2020 15:27, Tal Shnaiderman wrote:
>> Subject: Re: Windows: A fundamental issue (was eal/windows: definition for
>> ETOOMANYREFS errno)
>>
>> External email: Use caution opening links or attachments
>>
>>
>> 19/11/2020 14:21, Tal Shnaiderman:
>>>> Subject: Re: Windows: A fundamental issue (was eal/windows:
>>>> definition for ETOOMANYREFS errno)
>>>>
>>>> External email: Use caution opening links or attachments
>>>>
>>>>
>>>> Hi Nick,
>>>>
>>>>> This means that rte_os.h should not include POSIX/Linux
>>>>> definitions to avoid clashes such as the one seen with this
>>>>> change.  It's clearly not sustainable if applications have to be
>>>>> modified every time we add more Windows support to the DPDK.
>>>>>
>>>>> Note that this is not an isolated issue - most of the definitions
>>>>> in rte_os.h (redefining close, unlink, strdup etc) should not be
>>>>> present if other layers (application, other libraries, etc) are to
>>>>> be able to implement their own POSIX/Linux support.
>>>> The purpose of rte_os.h must be clarified. It now says:
>>>>
>>>> /**
>>>>   * This is header should contain any function/macro definition
>>>>   * which are not supported natively or named differently in the
>>>>   * ... OS. Functions will be added in future releases.
>>>>   */
>>>>
>>>> This doesn't specify if the file should expose wrappers or POSIX-named
>> bits.
>>>> Linux and FreeBSD, however, only use it for RTE_CPU_xxx() macros for
>>>> CPU_xxx() and don't define anything with POSIX names. So should
>> Windows.
>>>>> Please can we back this change out until we have a strategy that
>>>>> allows us to make these definitions available for 'internal' use,
>>>>> but prevent them being visible outside of the DPDK tree.  If we
>>>>> can't wrap them with
>>>>> rte_* yet, perhaps the short term solution could be as simple as
>>>>> setting RTE_DEFINE_POSIX when building DPDK code and hiding them
>>>>> if it is
>>>> not set?
>>>>
>>>> You need the same value both inside DPDK to return it and outside of
>>>> DPDK to match on it. Returning an unnamed, unspecified code is not an
>> option.
>>>> RTE_ prefix is a way to go. We can just rename ETOOMANYREFS.
>>> Thanks for the info Nick.
>>> Dmitry, If we go with RTE_ETOOMANYREFS, I assume we need to define it
>> for Linux and FreeBSD as well?
>>
>> Or we can use a "more standard" error code?
>>
> Right, Since it is used rarely and only in our PMD I'll work with the developer on selecting a different errno and will revert this commit, apologies for the inconvenience.
>
>>>> Strictly speaking, C standard defines very few errno, so using POSIX
>>>> values in API is incorrect anyway. It has to be deprecated and
>>>> removed eventually, we already had issues with MMAP_FAILED.
>>