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hello!
i have problems with a kernel module: when i insmod it, i get a segmentation
fault and "Unable to handle kernel paging request at virtual address
00000004" oops, so as far as i understand it, it seems like relocation does
not occur properly.
i can reproduce the problem with the attached simple test code. when i insmod
only hello_module.o it works fine, but when i insmod the result of "ld"
(mod.o) i get the error. so it seems the problem is with the linker. or am i
using wrong compiler / linker flags or doing something stupid?
i compile with "gcc -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer
- -fno-strict-aliasing -mno-abicalls -G 0 -fno-pic -mcpu=r4600 -mips2
- -Wa,--trap -pipe -mlong-calls -I/usr/src/linux/include -O3 -D__KERNEL__
- -DLINUX -DMESSAGES"
and link with "ld -r -o mod.o hello_module.o b.o"
versions:
* au1500 CPU
* kernel version 2.4.21-pre4 from cvs
* gcc version 3.0.4 (also: gcc version 2.95.4)
* GNU ld version 2.12.90.0.1 20020307 Debian/GNU Linux
* insmod version 2.4.15
objdump -x mod.o says:
- ---
mod.o: file format elf32-tradlittlemips
mod.o
architecture: mips:6000, flags 0x00000011:
HAS_RELOC, HAS_SYMS
start address 0x00000000
private flags = 10001001: [abi=O32] [mips2] [not 32bitmode]
Sections:
Idx Name Size VMA LMA File off Algn
0 .reginfo 00000018 00000000 00000000 00000034 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA, LINK_ONCE_SAME_SIZE
1 .text 00000070 00000000 00000000 00000050 2**4
CONTENTS, ALLOC, LOAD, RELOC, READONLY, CODE
2 .rodata 00000030 00000000 00000000 000000c0 2**4
CONTENTS, ALLOC, LOAD, READONLY, DATA
3 .modinfo 0000001c 00000000 00000000 000000f0 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
4 .data 00000000 00000000 00000000 00000110 2**4
CONTENTS, ALLOC, LOAD, DATA
5 .sbss 00000000 00000000 00000000 00000110 2**0
ALLOC
6 .bss 00000000 00000000 00000000 00000110 2**4
ALLOC
7 .comment 00000024 00000000 00000000 00000110 2**0
CONTENTS, READONLY
8 .pdr 00000040 00000000 00000000 00000134 2**2
CONTENTS, RELOC, READONLY
SYMBOL TABLE:
00000000 l d .reginfo 00000000
00000000 l d .text 00000000
00000000 l d *ABS* 00000000
00000000 l d *ABS* 00000000
00000000 l d .rodata 00000000
00000000 l d .modinfo 00000000
00000000 l d .data 00000000
00000000 l d .sbss 00000000
00000000 l d .bss 00000000
00000000 l d .comment 00000000
00000000 l d .pdr 00000000
00000000 l d *ABS* 00000000
00000000 l d *ABS* 00000000
00000000 l d *ABS* 00000000
00000000 l d *ABS* 00000000
00000000 l d *ABS* 00000000
00000000 l df *ABS* 00000000 hello_module.c
00000000 l O .modinfo 0000001b __module_kernel_version
00000000 l df *ABS* 00000000 b.c
00000004 g O .scommon 00000004 b
00000038 g F .text 00000000 cleanup_module
00000000 g F .text 00000000 init_module
00000000 *UND* 00000000 printk
00000004 g O .scommon 00000004 glob_int
RELOCATION RECORDS FOR [.text]:
OFFSET TYPE VALUE
00000008 R_MIPS_HI16 .rodata
0000000c R_MIPS_LO16 .rodata
00000010 R_MIPS_HI16 printk
00000014 R_MIPS_LO16 printk
00000028 R_MIPS_HI16 glob_int
0000002c R_MIPS_LO16 glob_int
00000040 R_MIPS_HI16 .rodata
00000044 R_MIPS_LO16 .rodata
00000048 R_MIPS_HI16 printk
0000004c R_MIPS_LO16 printk
RELOCATION RECORDS FOR [.pdr]:
OFFSET TYPE VALUE
00000000 R_MIPS_32 init_module
00000020 R_MIPS_32 cleanup_module
- ---
thanks for any hints.
btw: this issue is not related to the one i posted about before ("au1500mm
problems") - which is resolved already and was caused by a wrong
initialization of the dual PHY ethernet hardware.
bruno
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int b;
#define MODULE
#include <linux/module.h>
int glob_int;
int init_module(void) {
printk("<1>hello world\n");
glob_int = 0;
return 0;
}
void cleanup_module(void) {
printk("<1>goodby cruel world\n");
}
CC := gcc
CFLAGS := -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer -fno-strict-aliasing -mno-abicalls -G 0 -fno-pic -mcpu=r4600 -mips2 -Wa,--trap -pipe -mlong-calls -I/usr/src/linux/include -O3 -D__KERNEL__ -DLINUX -DMESSAGES
all: hello_module.o b.o
ld -r -o mod.o hello_module.o b.o
clean:
rm hello_module.o b.o
