Shared Library Issue HP UX

Thread Tools Search this Thread
Operating Systems HP-UX Shared Library Issue HP UX
# 1  
Old 08-07-2009
Shared Library Issue HP UX

I have never seen this issue before, but here is what is happening. I link an executable against two dynamic mlib libraries veclib and lapack. We place a newer version of these libraries in a write only directory and point the shlib_path at that directory. When the executable runs, it gets a page I/O modification error. The odd thing is we tracked it down to the executable modifying the two shared libraries. If the directory is writable the executable succeeds and the modification times on the shared libraries change. I don't have any idea why an executable would do anything to change a shared library at runtime or fail when it can't. Does anyone have any idea why this would occur. Is it that it is not the same library linked against. I didn't think this mattered for shared libraries as long as the calling convention is the same. So I am looking to try and figure out what weird behind the scenes thing is going on here. Thanks for any insight.
# 2  
Old 08-07-2009
I would question what odd thing dld has been asked to do.... it sounds like running code is attempting to write read-only memory.

what does the output of ldd show for one of the libraries?
# 3  
Old 08-08-2009
not ldd

I have already done an ldd and chatr, it depends on the libraries, the code hasn't changed in a long time, just a different setup it is being linked in. So are there any other thoughts out there?

---------- Post updated 08-08-09 at 08:11 AM ---------- Previous update was 08-07-09 at 07:06 PM ----------

Just wanted to see if anyone new out there had any thoughts on this issue.
# 4  
Old 08-11-2009
More information

I have tracked this issue to being something about memory locking over NFS. As soon as the process goes to mlockall, we update the modification time on the shared library. And if the shared library is read only, we get a Page I/O modification error. If I put the libraries local to the machine, it doesn't happen. So it seems to be some sort of NFS conflict. Has anyone seen this type of thing before?

---------- Post updated at 05:51 PM ---------- Previous update was at 06:35 AM ----------

found I was able to reproduce the symptom with just a hello world type of app.
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>

void main()
printf("hello world\n");

linked by the following
cc hello_world.c -o hello_world -L/opt/mlib/lib/pa2.0 -lveclib -llapack -Wl,s+

our home directories are NFS mounted so if I copy pa2.0 to /home/mine/pa2.0 and check the timestamp then
change my SHLIB_PATH EV to point to /home/mine/pa2.0
the timestamps change from the original copy after I run hello_world.
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. AIX

Add shared members from library to same library in a different directory

I'm trying to install libiconv to AIX 7.1 from an rpm off of the perzl site. The rpm appears to install but I get this error message. add shr4.o shared members from /usr/lib/libiconv.a to /opt/freeware/lib/libiconv.a add shr.o shared members from /usr/lib/libiconv.a to ... (5 Replies)
Discussion started by: kneemoe
5 Replies

2. Programming

Shared library with acces to shared memory.

Hello. I am new to this forum and I would like to ask for advice about low level POSIX programming. I have to implement a POSIX compliant C shared library. A file will have some variables and the shared library will have some functions which need those variables. There is one special... (5 Replies)
Discussion started by: iamjag
5 Replies

3. OS X (Apple)

Linking to a shared library

I'm trying to get Valgrind to work with an openmpi application in OS X. However I want to hardcode the path to a shared library called into my application so that it is available at runtime. In Linux this is relatively simple, I would just add the option... (0 Replies)
Discussion started by: Valgrinder
0 Replies

4. UNIX for Dummies Questions & Answers

Overhead of using a shared library

Hi, I found a very strange thing when I linked my executable with a shared library. That is the executable only references a small function of the shared library, and the size of this function is only hundred bytes, but when I check the /proc/pid/smaps, I found that the 'Rss' of this shared... (8 Replies)
Discussion started by: Dongping84
8 Replies

5. Shell Programming and Scripting

How to change a Makefile from building static library to shared library?

Hi: I have a library that it only offers Makefile for building static library. It built libxxx.a file. How do I in any way build a shared library? (either changin the Makefile or direct script or command to build shared library) Thanks. (1 Reply)
Discussion started by: cpthk
1 Replies

6. Programming

Shared memory for shared library

I am writing a shared library in Linux (but compatible with other UNIXes) and I want to allow multiple instances to share a piece of memory -- 1 byte is enough. What's the "best" way to do this? I want to optimize for speed and portability. Obviously, I'll have to worry about mutual exclusion. (0 Replies)
Discussion started by: otheus
0 Replies

7. Programming

Using funcion in a shared library

Is there any way in C to access a function in C shared library. I have used dlopen to access /load the c shared library but unable to use the function in the shared object. Thanks in advance :b: (1 Reply)
Discussion started by: yhacks
1 Replies

8. Programming

Shared memory in shared library

I need to create a shared library to access an in memory DB. The DB is not huge, but big enough to make it cumbersome to carry around in every single process using the shared library. Luckily, it is pretty static information, so I don't need to worry much about synchronizing the data between... (12 Replies)
Discussion started by: DreamWarrior
12 Replies

9. UNIX for Advanced & Expert Users

shared library

What is the primary difference between static library and dynamic library? and how to write static shared library? (1 Reply)
Discussion started by: areef4u
1 Replies

10. Programming

Shared Library

hello all I want to work in shared libraries how can i work in Linux Environment ? (2 Replies)
Discussion started by: rajashekaran
2 Replies
Login or Register to Ask a Question