Thiemo Seufer wrote:
Gregor Waltz wrote:
Atsushi Nemoto wrote:
On Fri, 11 Jan 2008 12:49:49 -0500, Gregor Waltz <gregor.waltz@xxxxxxxxxxx> wrote:
I built linux-2.6.23.9 with the above, but the results are still the
same and the EPC is not in System.map.
Are you searching the exact EPC value in System.map?
Usually you should find a function symbol which contains the EPC value in it.
Or you can do "mipsel-linux-objdump -d vmlinux" and search the EPC value.
The current error is:
Exception! EPC=80026290 CAUSE=00000020(Sys)
80026290 0000000c syscall
80026290 is not in System.map, however, the objdump is much more
informative and does contain that value. That particular syscall is in:
8002628c <kernel_execve>:
8002628c: 24020fab li v0,4011
80026290: 0000000c syscall
80026294: 00401821 move v1,v0
80026298: 14e00003 bnez a3,800262a8 <kernel_execve+0x1c>
8002629c: 00000000 nop
800262a0: 03e00008 jr ra
800262a4: 00601021 move v0,v1
800262a8: 03e00008 jr ra
800262ac: 00031023 negu v0,v1
Does that provide any clues?
The kernel failed to set up the general exception handler correctly.
It should have done that before attempting to start the first kernel
thread.
Thiemo
From where in the kernel image should execution begin?
Presuming that the output of "objdump -d" reflects the disassembled
binary from the beginning in order, it looks like my 2.6 kernel is
running straight into run_init_process as the first real code executed.
From what I have seen in the kernel code, run_init_process should be
jumped to far later in the boot process. If what I am thinking is
correct, then it also explains why the failure happens in kernel_execve.
I have also included the start of my working kernel, which has _ftext
with non-zero data as its first entry. Is the _ftext the ELF header or
some other info for the boot loader?
Thanks
linux-2.6.23.9/vmlinux: file format elf32-tradlittlemips
Disassembly of section .text:
80020000 <run_init_process-0x400>:
...
80020400 <run_init_process>:
80020400: 3c028033 lui v0,0x8033
80020404: 3c068033 lui a2,0x8033
80020408: 244594dc addiu a1,v0,-27428
8002040c: 24c69450 addiu a2,a2,-27568
80020410: 080098a3 j 8002628c <kernel_execve> //
Should this be happening already?
80020414: ac4494dc sw a0,-27428(v0)
80020418 <init_post>:
run_init_process is from linux-2.6.23.9/init/main.c
Our working kernel starts differently:
linux-2.4.12/vmlinux: file format elf32-tradlittlemips
Disassembly of section .text:
80020000 <_ftext>:
80020000: 26 80 01 3c 14 42 3d ac 02 80 08 3c 80 04 08 25
&..<.B=....<...%
80020010: 08 00 00 01 00 00 00 00 00 00 00 00 00 00 00 00
................
...
80020298 <except_vec2_generic>:
80020298: 401a8000 mfc0 k0,$16
8002029c: 241bfff8 li k1,-8
800202a0: 035bd024 and k0,k0,k1
800202a4: 375a0002 ori k0,k0,0x2
800202a8: 409a8000 mtc0 k0,$16
...
800202b8: 0800b248 j 8002c920 <cache_parity_error>
800202bc: 00000000 nop
800202c0 <except_vec4>:
