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
Penguin : Linux version 2.6.11.9 on an i686 machine (5537.79 BogoMips).
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