From: Kwanghoon Choi <khchoi@ruby.kaist.ac.kr>
To: gcc-help@gcc.gnu.org
Cc: Kwanghoon Choi <khchoi@ruby.kaist.ac.kr>
Subject: Help?
Date: Tue, 02 Jan 2001 18:27:00 -0000 [thread overview]
Message-ID: <Pine.SOL.4.05.10101031040190.23560-100000@ruby.kaist.ac.kr> (raw)
Hello all,
I would like to know the precise sequence of loading and execution of
a given executable. In my specific flatform (the ARM machine, uclinux kernel,
gcc, and glibc), I am using binary executables in a flat form, not like ELF.
The below simple program gets crashed whenever I compile the program with
-lpthread even if the program does not use the thread library. If I omit
the option -lpthread, it works well!
main()
{
int childpid;
if( (childpid = vfork()) == -1 ) {
/* can't vfork */
}
else if(childpid == 0) {
/* child process */
}
else {
/* parent process */
}
}
I know it is foolish to give the option -lpthread in my simple program,
but it is just a test to resolve my questions to be explained.
In order to examine why, I instrumented some printf-like functions into
uclinux kernel sources and glibc sources.
By instrumenting pthread library functions in glibc, I found that
pthread_initialize() gets called before the main() function.
The reason seems to be that the function is declared as this:
static void pthread_initialize(void) __attribute__((constructor));
My execution sequence is like this as far as I know by instrumenting
printf-like functions.
KERNEL : ...
search_binary_handler() // load an executable in a flat form
do_load_flat_binary() // $UCLINUX/fs/binfmt_flat.c
...
wake_up() // the process for the executable
// gets control
???
USER : ???
__libc_start_main // $GLIBC/sysdeps/generic/libc-start.c
// glibc's entry ?
???
pthread_initialize() // $GLIBC/linuxpthread/pthread.c
// pthread initialization
...
main() // user's program
First, I don't know who really calls __libc_start_main() functions. Notice
that it receives several arguments, mostly function pointers.
int __libc_start_main (int (*main) (int, char **, char **), int argc,
char **argv, void (*init) (void), void (*fini) (void),
void (*rtld_fini) (void), void *stack_end)
{
...
}
Second, though I know pthread_initialize() is (indirectly) called in the
__libc_start_main(), I don't know where exectly. The reason is that
pthread_initialize() seems to be called via some function pointer, e.g. init().
Third, I don't know how GCC compiles the functions declared with
__attribute__((constructor)). I would like to know the compilation
strategy specifically in the flat-formed executable.
Although I will check this mailing list reguraly, it would be happy
to forward your reply to khchoi@pllab.kaist.ac.kr.
Thank you for reading my long mail.
Kwanghoon
p.s. I looked around the site of GCC online documentation
( http://www.gnu.org/software/gcc/onlinedocs/ )
but it contains some broken links, e.g. for GCC manual
( http://gcc.gnu.org/onlinedocs/gcc_toc.html )
next reply other threads:[~2001-01-02 18:27 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-01-02 18:27 Kwanghoon Choi [this message]
2001-01-02 19:37 ` Help? Alexandre Oliva
-- strict thread matches above, loose matches on Subject: below --
2018-06-01 15:58 Help!! Tomas Ukkonen
2006-12-26 13:38 help!! manish manish
2006-12-27 17:01 ` help!! Ian Lance Taylor
2006-01-28 5:42 Help? Garvin Pang
2006-01-28 7:41 ` Help? Brian Dessent
2005-06-02 15:54 help_ imacat
2003-07-12 10:05 help? Shen Hui
2003-03-03 17:37 help!!! Jim Frost
2003-03-07 5:46 ` help!!! LLeweLLyn Reese
[not found] <20021204042724.64819.qmail@web15002.mail.bjs.yahoo.com>
2002-12-04 0:16 ` help! Ben Elliston
2002-11-19 10:16 help!!! mingo lu
[not found] <20020617195757.13842.qmail@uwdvg001.cms.usa.net>
2002-06-17 13:05 ` help!! Phil Edwards
2002-04-04 23:41 Help! 朱 少波
2000-05-15 9:15 HELP!!! Michael Michael
2000-05-16 23:27 ` HELP!!! Martin v. Loewis
2000-03-08 14:14 HELP !!! FabrÃcio Souza
2000-03-09 17:00 ` Alexandre Oliva
2000-04-01 0:00 ` Alexandre Oliva
2000-04-01 0:00 ` FabrÃcio Souza
2000-02-24 0:56 Help! 陳鵬升
2000-04-01 0:00 ` Help! 陳鵬升
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=Pine.SOL.4.05.10101031040190.23560-100000@ruby.kaist.ac.kr \
--to=khchoi@ruby.kaist.ac.kr \
--cc=gcc-help@gcc.gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).