Issue
On a Linux 2.4.25 system I have two loadable kernel modules, com20020 and xsoe. These modules should be independent of each other, but /proc/modules has the lines
xsoe 4528 0 (unused)
com20020 10112 0 [xsoe]
- saying that xsoe is referring to com20020. Perhaps there is a programming error so that xsoe inadvertently uses a symbol from com20020. How can I find the cause of this dependency (preferably without unloading com20020)? (depmod -n offers no clue.)
Solution
I looked at /proc/ksyms for suspicious symbols in com20020 which might also appear in the source of xsoe; eventually I saw the line
d129e694 debug [com20020]
there. Both the sources of com20020 and xsoe had the definitions unsigned debug; MODULE_PARM(debug, "i"); and in the outputs of nm com20020.o and nm xsoe.o the symbol appeared as common:
00000004 C debug
The cure was to define the object debug to have internal linkage (storage-class
static).
The search for common symbols could be automated with a bash command like
join -j 3 <(nm com20020.o) <(nm xsoe.o)|grep C$
Answered By - Armali
