Mirror of the gdb mailing list
 help / color / mirror / Atom feed
From: Bjoern Doebel <bjoern.doebel@gmail.com>
To: Tom Frank <gdbhelper@gmail.com>
Cc: gdb@sourceware.org
Subject: Re: How can I explain for this? what is __kernel_vsyscall () ?
Date: Wed, 11 Jul 2012 10:38:00 -0000	[thread overview]
Message-ID: <CAGLi7wpmUQRvvVbWNcFdiDJdoiXLygCvDCszDEF5F0UOGJtzpA@mail.gmail.com> (raw)
In-Reply-To: <CAMHBcgoGHAh6i4-HoUBURaNvViY6CmarRge_-rKyZd7hFqO00A@mail.gmail.com>

2012/7/11 Tom Frank <gdbhelper@gmail.com>:
> I debug a multithreads  programme  with gdb,as it runs  I  use the
> 'info threads' command, and find that  most of the threads running at
> __kernel_vsyscall () function
>
> as below:
>
>   6    Thread 0xb61e4b90 (LWP 322) 0x008e7402 in __kernel_vsyscall ()
>   5    Thread 0xb6be5b90 (LWP 320) 0x008e7402 in __kernel_vsyscall ()
>   4    Thread 0xb7fe7b90 (LWP 318) 0x008e7402 in __kernel_vsyscall ()
>   3    Thread 0xb75e6b90 (LWP 316) 0x008e7402 in __kernel_vsyscall ()
> * 1    Thread 0xb7fe86d0 (LWP 312) 0x0074c2b8 in clone () from
> /lib/i686/nosegneg/libc.so.6
>
>
>
> what is __kernel_vsyscall (),  why most threads's frame  is in that  step ?

__kernel_vsyscall() is Linux' system call entry point and the threads
you are looking at seem to be blocking in such a syscall. To find out
which it is, you might want to have a look at their EAX register
(assuming you're on x86).

Bjoern


      reply	other threads:[~2012-07-11 10:38 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-07-11 10:12 Tom Frank
2012-07-11 10:38 ` Bjoern Doebel [this message]

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=CAGLi7wpmUQRvvVbWNcFdiDJdoiXLygCvDCszDEF5F0UOGJtzpA@mail.gmail.com \
    --to=bjoern.doebel@gmail.com \
    --cc=gdb@sourceware.org \
    --cc=gdbhelper@gmail.com \
    /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