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

[Tal Shnaiderman <talshn@nvidia.com>]

> 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.
> 
>