Re: [ERROR] perf build failure on current tip:perf/core

From: Ingo Molnar
Date: Sun Jan 08 2012 - 09:03:30 EST



* Namhyung Kim <namhyung@xxxxxxxxx> wrote:

> >> $ map pwrite
> >> The program 'map' is currently not installed. You can install it by
> >> typing:
> >> sudo apt-get install sgt-puzzles
> >>
> >> I don't think this is the package what you said. Anyway quick grep'ing
> >> pwrite tells me it's in the unistd.h:
> >>
> >> $ grep pwrite /usr/include/unistd.h
> >> extern ssize_t pwrite (int __fd, __const void *__buf, size_t __n,
> >> extern ssize_t __REDIRECT (pwrite, (int __fd, __const void *__buf,
> >> pwrite64) __wur;
> >> # define pwrite pwrite64
> >
> > There's multiple definitions there, and we get lost somehow - as
> > unistd.h is included:
> >
> > ~/tip/tools/perf> grep -n unistd.h util/trace-event-info.c
> > 34:#include <unistd.h>
> >
> > Thanks,
> >
> > Ingo
>
> This is the content of my /usr/include/unistd.h:
>
> #ifdef __USE_UNIX98
> # ifndef __USE_FILE_OFFSET64
> extern ssize_t pread (int __fd, void *__buf, size_t __nbytes,
> __off_t __offset) __wur;
> extern ssize_t pwrite (int __fd, __const void *__buf, size_t __n,
> __off_t __offset) __wur;
> # else
> # ifdef __REDIRECT
> extern ssize_t __REDIRECT (pread, (int __fd, void *__buf, size_t __nbytes,
> __off64_t __offset),
> pread64) __wur;
> extern ssize_t __REDIRECT (pwrite, (int __fd, __const void *__buf,
> size_t __nbytes, __off64_t __offset),
> pwrite64) __wur;
> # else
> # define pread pread64
> # define pwrite pwrite64
> # endif
> # endif
>
> # ifdef __USE_LARGEFILE64
> extern ssize_t pread64 (int __fd, void *__buf, size_t __nbytes,
> __off64_t __offset) __wur;
> extern ssize_t pwrite64 (int __fd, __const void *__buf, size_t __n,
> __off64_t __offset) __wur;
> # endif
> #endif
>
> I think all of pread/write functions are properly defined here:
>
> $ echo '#include <unistd.h>' | \
> > gcc -xc -E -dM -D_GNU_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 - | \
> > grep -e UNIX98 -e LARGEFILE64 -e FILE_OFFSET
> #define __ILP32_OFFBIG_CFLAGS "-m32 -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64"
> #define _LARGEFILE64_SOURCE 1
> #define __USE_UNIX98 1
> #define __USE_LARGEFILE64 1
> #define _FILE_OFFSET_BITS 64
> #define __USE_FILE_OFFSET64 1

So which preprocessor branch within unistd.h does it get into on
your system and why isnt there a pwrite()/pwrite64() prototype
once it goes along that path?

You could try an ugly approach and edit your unistd.h and put in
debug lines like this:

#warn got here: __LINE__

and thus see which branch it really gets into.

(save a backup copy of unistd.h first ;-)

Thanks,

Ingo
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