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

[Bruce Richardson <bruce.richardson@intel.com>]

On Sun, Mar 15, 2020 at 09:36:11AM +0100, Thomas Monjalon wrote:
> 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.
> 

Rather than splitting, we can still fix this by breaking the dependency by
just not having rte_debug.h included in rte_pci.h. From what I see, there
is no need for that include to be there, and DPDK pretty much compiles fine
with it removed - the only other change I had to make was add an extra
include into mlx5_common.h to compensate for it not getting pulled in via
rte_pci.h.

Generally, while we should ensure that each header includes any other
headers it depends upon, we must be careful that headers don't include
other headers that they don't directly use.

/Bruce