How to know the library name when I already know function name

letuanle · 06-05-2007, 04:42 AM

Dear all,

When I call a function in linux kernel, I want to know what library name contains that function. Please give me the solution.

For example, I want to know the name of library which contains local_bh_enable()

Thank you
Tuan Le

Centinul · 06-06-2007, 01:21 PM

Function: Google
Input: local_bh_enable()
Output: asm/smp.h

In all seriousness, I don't know how you would try and use a function (assuming C) in C without knowing the library you are calling it from. If you don't include the library than you can't call the function.

Do you think you could explain a little more clearly what you are trying to do?

Thanks

letuanle · 06-06-2007, 10:08 PM

Hello Centinul,

It is easy to know which .h file need to include into my source code which calling the local_bh_enable() function. But when I compile, the error occurs (cannot link the library). I need to know the name of library which contains local_bh_enable() to pass to the command line

gcc myproject -lXX

My question is XX = ?

(XX is the name of library which contains local_bh_enable())

Thank you

Tuan Le

The_Nerd · 06-07-2007, 12:03 AM

Do a google search: http://www.google.com/search?client=...utf-8&oe=utf-8

kaz2100 · 06-07-2007, 11:32 PM

Hya,

I had same question a while ago. I did not know the answer. So that, I used "nm" to see. But it did not work on Penguin. It worked with Macintosh.

Also it was not efficient at all....

Happy Penguins!

haxpor · 06-08-2007, 01:51 AM

The library contains in Linux is in Binary Code, so we cannot search it like the header file, I guess the only way we can do is search through the internet.

Any better ideas?

makyo · 06-08-2007, 06:11 AM

Hi.

Quote:

Originally Posted by kaz2100

I had same question a while ago. I did not know the answer. So that, I used "nm" to see. But it did not work on Penguin. It worked with Macintosh.

Also it was not efficient at all....

My experience is different from this. The utility nm has worked on every *nix system I have used. I don't know what Penguin is, however.

What do you mean by not efficient at all? ... cheers, makyo

kaz2100 · 06-08-2007, 08:06 AM

Hya,

My Penguin is etch Debian. 2.6.20.11

Code:

>nm /lib/libm-2.3.6.so
nm: /lib/libm-2.3.6.so: no symbols

It is quite inefficient. Follow links to real one (/usr/lib/libm.so -> /lib/libm.so -> lib/libm-2.3.6.so) on every individual library until I find.

makyo · 06-08-2007, 08:53 AM

Hi.

Quote:

-D
--dynamic
Display the dynamic symbols rather than the normal symbols. This
is only meaningful for dynamic objects, such as certain types of
shared libraries.

-- excerpt from man nm

For example:

Code:

#!/bin/sh

# @(#) s1       Demonstrate nm extraction of symbols from shared libraries.

set -o nounset
echo " sh version: $BASH_VERSION"

LIB=/usr/lib/libm.a
echo
echo " Looking at $LIB:"
nm $LIB 2>/dev/null | head -10

LIB=/lib/libm-2.3.2.so
echo
echo " Looking at $LIB:"
nm -D $LIB 2>/dev/null | head -10

exit 1

Which produces:

Code:

% ./s1
 sh version: 2.05b.0(1)-release

 Looking at /usr/lib/libm.a:

k_standard.o:
         U _LIB_VERSION
         U __assert_fail
         U __copysign
         U __errno_location
00000000 T __kernel_standard
         U __rint
         U fputs
         U fwrite

 Looking at /lib/libm-2.3.2.so:
00000000 A GLIBC_2.0
00000000 A GLIBC_2.1
00000000 A GLIBC_2.2
         w _Jv_RegisterClasses
00021538 D _LIB_VERSION
         U __assert_fail
0000c380 T __clog10
00013090 T __clog10f
0001a7b0 T __clog10l
         w __cxa_finalize

If I understand your comment regarding the inefficiency of following links, that seems to be an issue of the design of library layout, rather than nm. Please clarify if I have not understood correctly ... cheers, makyo