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
> 
> 
> 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?

> 
> 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.