[dpdk-dev] [PATCH v4 1/7] eal: introduce portable format attribute

[Thomas Monjalon]

14/03/2020 00:38, Dmitry Kozlyuk:
> > I suggest this change (I can send a patch fixing the issue in other .h files):
> >
> > +/*
> > + * RTE_TOOLCHAIN_GCC is true if the target is built with GCC,
> > + * while a host application (like pmdinfogen) may have another compiler.
> > + * RTE_CC_IS_GNU is true if the file is compiled with GCC,
> > + * no matter it is a target or host application.
> > + */
> > +#if defined __GNUC__ && !defined __clang__ && !defined __INTEL_COMPILER
> > +#define RTE_CC_IS_GNU
> > +#endif
> > +
> > +#ifdef RTE_CC_IS_GNU
> > -/** Define GCC_VERSION **/
> > -#ifdef RTE_TOOLCHAIN_GCC
> >  #define GCC_VERSION (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + \
> >                 __GNUC_PATCHLEVEL__)
> >  #endif
> > @@ -96,7 +105,7 @@ typedef uint16_t unaligned_uint16_t;
> >   * even if the underlying stdio implementation is ANSI-compliant,
> >   * so this must be overridden.
> >   */
> > -#if defined(RTE_TOOLCHAIN_GCC)
> > +#ifdef RTE_CC_IS_GNU
> >  #define __rte_format_printf(format_index, first_arg) \
> >         __attribute__((format(gnu_printf, format_index, first_arg)))
> >  #else
> 
> The code you propose LGTM itself. If you think it's a better solution than
> the one proposed below, I see no problem going with it.
> 
> What I wonder is whether pmdinfogen should include the problematic code in the
> first place. The errors come from declarations in rte_debug.h, but pmdinfogen
> really can't use them, because definitions are compiled for different
> machine. Pmdinfogen pulls rte_debug.h via rte_pci.h, which is only needed for
> struct rte_pci_id. Shouldn't we instead break this bogus dependency chain by
> moving struct rte_pci_id to a separate header?

Splitting headers to avoid EAL dependency looks to be a bad precedent to me.

> EAL defines are tied to the target toolchain and are consistent with each
> other, from this point of view RTE_CC_IS_GNU looks like a workaround.

Yes there are some target-arch-dependent code in EAL.
But a host application is not supposed to use arch-dependent code.

> Another
> reason why pmdinfogen should not depend on EAL is that its code will differ
> considerably for POSIX and Windows (ELF vs COFF, mmap vs Win32 API).

I believe managing some OS differences should be helped with EAL.