[DTrace-devel] [PATCH 05/17] uapi headers: include <sys/dtrace_types> as needed

[Kris Van Hees]

On Tue, Aug 30, 2022 at 08:13:47PM -0400, Eugene Loh via DTrace-devel wrote:
> Reviewed-by: Eugene Loh <eugene.loh at oracle.com>
> 
> But:
> 
> *)  Should we add tests?  (I'm not convinced we should -- there are too many
> code paths -- but see next item.)
> 
> *)  Maybe in addition to the fix one should replace (the following is
> pseudocode):
> 
>         #if THISENDIANNESS
>                 // this endianness
>         #else
>                 // that endianness
>         #endif
> 
>     with
> 
>         #if THISENDIANNESS
>                 // this endianness
>         #elif THATENDIANNESS
>                 // that endianness
>         #else
>                 error do not compile
>         #endif

But sys/dtrace_types.h already contains:

#if __BYTE_ORDER == __LITTLE_ENDIAN
#define _LITTLE_ENDIAN 1
#elif __BYTE_ORDER == __BIG_ENDIAN
#define _BIG_ENDIAN 1
#else
#warning Unknown endianness
#endif

So there is no need to do this once again.  I do not believe that there is any
expectation that DTrace will ever get ported to a system that has neither
little nor big endianness. 

> On 8/10/22 18:06, Nick Alcock via DTrace-devel wrote:
> > This is needed for _LITTLE_ENDIAN etc: without it, consumers are liable
> > to find that they think they're on a big-endian system even when they're
> 
> Think they're on a BE system?  Well, it depends on how the code is written: 
> the error might induce one to thinking they're on a little-endian machine. 
> Anyhow, the commit message can be written in a way that does not assume
> which way the #ifdef is written.
> 
> > not.
> > ---
> >   include/dtrace/actions_defines.h | 1 +
> >   include/dtrace/dof_defines.h     | 1 +
> >   2 files changed, 2 insertions(+)
> > 
> > diff --git a/include/dtrace/actions_defines.h b/include/dtrace/actions_defines.h
> > index dfec34f3ddc2..f161df7cf13f 100644
> > --- a/include/dtrace/actions_defines.h
> > +++ b/include/dtrace/actions_defines.h
> > @@ -13,6 +13,7 @@
> >   #ifndef _DTRACE_ACTIONS_DEFINES_H
> >   #define _DTRACE_ACTIONS_DEFINES_H
> > +#include <sys/dtrace_types.h>
> >   #include <dtrace/universal.h>
> >   /*
> > diff --git a/include/dtrace/dof_defines.h b/include/dtrace/dof_defines.h
> > index 02d650c22831..818089d1b472 100644
> > --- a/include/dtrace/dof_defines.h
> > +++ b/include/dtrace/dof_defines.h
> > @@ -13,6 +13,7 @@
> >   #ifndef _DTRACE_DOF_DEFINES_H
> >   #define _DTRACE_DOF_DEFINES_H
> > +#include <sys/dtrace_types.h>
> >   #include <dtrace/universal.h>
> >   /*
> 
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