Re: Illegal use of reserved word in system.h

[Richard B. Johnson]

On Thu, 19 May 2005, Maciej W. Rozycki wrote:

> On Thu, 19 May 2005, Arjan van de Ven wrote:
>
> > > First off, I think we need a system-call that will return some of
> > > the information that now comes from headers. PAGE_SIZE comes to
> > > mind. You need this for mmap() but there doesn't seem to be any
> > > way to get it. getpagesize() 'C' library just returns something
> > > it's swiped from kernel headers when the library was compiled.
> > > There are other things like the following that sometimes need
> >
> > for getpagesize() I can see the point
>
> If that is the case, then that's a bug in that C library, which should be
> reported and fixed.  When starting a program, i.e. as a result of
> execve(), Linux passes the current page size in use in the auxiliary
> vector.  That value should be retrieved and used by a C library for
> platforms that support various page sizes and returned by library calls
> like getconf().  For example glibc gets it right.
>
>  Maciej

Would you please explain 'auxiliary' vector???

According to the documentation, the following information
is passed to a program:

#
#   %edx        Contains a function pointer to be registered with `atexit'.
#               This is how the dynamic linker arranges to have DT_FINI
#               functions called for shared libraries that have been loaded
#               before this code runs.
#
#   %esp        The stack contains the arguments and environment:
#               (%esp)                  argc
#               4(%esp)                 argv[0]
#               ...
#               (4*argc)(%esp)          NULL
#               (4*(argc+1))(%esp)      envp[0]
#               ...
#                                       NULL
#

Now, where is that 'auxiliary vevtor'??? I got a pointer to
something to be executed before calling exit, I have an
argument count, then a bunch of pointers (argv), terminating
with a NULL, then another bunch of pointers (envp) terminating
with a NULL.  Is there something after that??? If so, what's
the contents of this thing?


Cheers,
Dick Johnson
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