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

[Thomas Monjalon]

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?


> > 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.