While trimming the kernel size to try kexec on real hardware with only
12 MiB of RAM, I got several weird crashes and lock-ups indicating memory
corruption somewhere (illegal instructions, BUG()s for incorrect magics in
fresh lock objects, ...).
As I also got complaints about overlapping sections from strip, I switched
from the good old gcc 4.1.2 20061115 (prerelease) (Ubuntu 4.1.1-21)
and binutils 2.18.0.20080103 to gcc 4.6.3 and binutils 2.22, but apart
from fixing the overlapping sections, it still didn't work.
After lots of serial debugging, I ended up bisecting the configs, and it
turned out that CONFIG_XZ_DEC was the difference between a working
and non-working kernel.
However, just disabling CONFIG_XZ_DEC on one of my defconfigs
still gave a working kernel. So there must be a deeper issue.
It seems like non-working kernel have lost the CONTENTS, LOAD,
READONLY, and DATA attributes of the __modver section:
vmlinux.ok5: file format elf32-m68k
Sections:
Idx Name Size VMA LMA File off Algn
0 .text 0014986c 00001000 00001000 00001000 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
1 __ex_table 000022b8 0014a870 0014a870 0014a870 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
2 .rodata 0003a900 0014d000 0014d000 0014d000 2**4
CONTENTS, ALLOC, LOAD, READONLY, DATA
3 __param 000002f0 00187900 00187900 00187900 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
4 __modver 00000410 00187bf0 00187bf0 00187bf0 2**1
CONTENTS, ALLOC, LOAD, READONLY, DATA
5 .data 000137c0 00188000 00188000 00188000 2**4
CONTENTS, ALLOC, LOAD, DATA
6 .bss 0001b040 0019b7c0 0019b7c0 0019b7c0 2**4
ALLOC
7 .init.text 0000db5e 001b7000 001b7000 0019d000 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
8 .init.data 00003004 001c4b60 001c4b60 001aab60 2**2
CONTENTS, ALLOC, LOAD, DATA
9 .m68k_fixup 00000908 001c7b64 001c7b64 001adb64 2**0
CONTENTS, ALLOC, LOAD, DATA
10 .notes 00000024 001c846c 001c846c 001ae46c 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
11 .init_end 00000b70 001c8490 001c8490 001ae490 2**0
ALLOC
12 .comment 00000011 00000000 00000000 001ae490 2**0
CONTENTS, READONLY
vmlinux.crash5: file format elf32-m68k
Sections:
Idx Name Size VMA LMA File off Algn
0 .text 00147824 00001000 00001000 00001000 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
1 __ex_table 000022b8 00148830 00148830 00148830 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
2 .rodata 0003a770 0014b000 0014b000 0014b000 2**4
CONTENTS, ALLOC, LOAD, READONLY, DATA
3 __param 000002f0 00185770 00185770 00185770 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
4 __modver 000005a0 00185a60 00185a60 00185a60 2**0
ALLOC
5 .data 000137a0 00186000 00186000 00186000 2**4
CONTENTS, ALLOC, LOAD, DATA
6 .bss 0001b040 001997a0 001997a0 001997a0 2**4
ALLOC
7 .init.text 0000db5e 001b5000 001b5000 0019b000 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
8 .init.data 00003004 001c2b60 001c2b60 001a8b60 2**2
CONTENTS, ALLOC, LOAD, DATA
9 .m68k_fixup 00000908 001c5b64 001c5b64 001abb64 2**0
CONTENTS, ALLOC, LOAD, DATA
10 .notes 00000024 001c646c 001c646c 001ac46c 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
11 .init_end 00000b70 001c6490 001c6490 001ac490 2**0
ALLOC
12 .comment 00000011 00000000 00000000 001ac490 2**0
CONTENTS, READONLY
Does anyone have a clue? Who controls the presence of these
attributes?
Thanks in advance!
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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