[Dprobes] 3.6.3/newbie question: dpcc and lookup_symbol()...

[Chris J. <cp...@we...>]

Hi:
Newbie build problem. Thanks for any information! (I have the dprobes
command working at least today).

Using dprobes3.6.3, on redhat7.2 patched to March, lookup_symbol() of
do_fork is failing, although the symbol table loads. I must have built
something incorrectly; or are only certain kernel compile options
supported? 

gdb sources are 5.1-1, built in /usr/src/redhat/BUILD/gdb-5.1

Anomoly during build: during patch-dpcc, c_hll_lang.l and c_hll_lang.y
were identified as already patched.
Otherwise it built cleanly.

Anomoly in cmd/ dir: I did notice that in the cmd/ directory, dprobes
did not build properly due to libbfd.a symbols missing (e.g.
htab_create). I linked explicitly with the libiberty.a and libbfd.a from
the gdb 5.1-1 source to workaround that problem.

[root@sld12 dpcc-1.0.1]# file /usr/src/linux/vmlinux
/usr/src/linux/vmlinux: ELF 32-bit LSB executable, Intel 80386, version
1, statically linked, not stripped
[root@sld12 dpcc-1.0.1]# nm !$ | grep do_fork
nm /usr/src/linux/vmlinux | grep do_fork
c011bcb8 T do_fork

./dpcc kernel-param.dpc
Preprocessing: gcc -E -xc -o /tmp/dpc1YLfjE kernel-param.dpc
Loading symbol file /usr/src/linux/vmlinux
Unable to find function do_fork

2436  open("/usr/src/linux/vmlinux", O_RDONLY) = 6
2436  fcntl64(0x6, 0x3, 0, 0x40015e8c)  = 0
2436  fcntl64(0x6, 0x3, 0xbffff7e8, 0)  = 0
2436  fstat64(6, {st_mode=S_IFREG|0755, st_size=4157609, ...}) = 0
2436  old_mmap(NULL, 4096, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x4001a000
2436  _llseek(6, 0, [0], SEEK_CUR)      = 0
2436  read(6,
"\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\2\0\3\0\1\0\0\0\0P\20\300"..., 4096) =
4096
2436  _llseek(6, 3457024, [3457024], SEEK_SET) = 0
2436  read(6,
"\0\00001.01\0\0\0\10\0\0\0\0\0\0\0\1\0\0\00001.01\0\0\0"..., 4096) =
4096
2436  _llseek(6, 3461120, [3461120], SEEK_SET) = 0
2436  _llseek(6, 0, [0], SEEK_SET)      = 0
2436  read(6,
"\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\2\0\3\0\1\0\0\0\0P\20\300"..., 4096) =
4096
2436  write(2, "Unable to find function do_fork\n", 32) = 32