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    SubjectRe: NULL pointer dereference with pre 2.1.37-4
    Linus Torvalds writes:
    >
    > Ho humm..

    The mailing list seems to be down right now...
    Mail Queue (1 request)
    --Q-ID-- --Size-- -----Q-Time----- ------------Sender/Recipient------------
    TAA07689 5 Tue May 6 19:09 wwc
    (Deferred: Connection refused by vger.rutgers.edu.)
    Majordomo@vger.rutgers.edu
    ... since about 12 hours.

    > What version of "objcopy" are people using? The more I look at the panics
    > with "Code: 00 00 00 00 ...", the more I feel that they are the result of
    > the ".text.lock" segment of the kernel simply missing.

    It was both 2.8 and 2.7.0.9 (aka 970202). The .text.lock segment is present.
    > objdump --headers vmlinux

    vmlinux: file format elf32-i386

    Sections:
    Idx Name Size VMA LMA File off Algn
    0 .text 000bfac6 c0100000 c0100000 00001000 2**4
    CONTENTS, ALLOC, LOAD, READONLY, CODE
    1 .text.lock 0000120e c01bfac6 c01bfac6 000f8000 2**0
    CONTENTS, READONLY
    2 .rodata 00017cbd c01c0cd4 c01c0cd4 000c0cd4 2**2
    CONTENTS, ALLOC, LOAD, READONLY, DATA
    3 .kstrtab 00002f94 c01d8991 c01d8991 000d8991 2**0
    CONTENTS, ALLOC, LOAD, READONLY, DATA
    4 __ex_table 000016e8 c01db930 c01db930 000db930 2**2
    CONTENTS, ALLOC, LOAD, READONLY, DATA
    5 __ksymtab 00000fb0 c01dd018 c01dd018 000dd018 2**2
    CONTENTS, ALLOC, LOAD, READONLY, DATA
    6 .data 000125c8 c01ddfd0 c01ddfd0 000ddfd0 2**4
    CONTENTS, ALLOC, LOAD, DATA
    7 .text.init 00006581 c01f1000 c01f1000 000f1000 2**2
    CONTENTS, ALLOC, LOAD, READONLY, CODE
    8 .data.init 0000007c c01f7584 c01f7584 000f7584 2**2
    CONTENTS, ALLOC, LOAD, DATA
    9 .bss 0003a990 c01f8000 c01f8000 000f8000 2**3
    ALLOC
    10 .stab 00014910 00000000 00000000 000f9210 2**2
    CONTENTS, READONLY, DEBUGGING
    11 .stabstr 0000ef58 00000000 00000000 0010db20 2**0
    CONTENTS, READONLY, DEBUGGING
    12 .comment 000013c4 00000000 00000000 0011ca78 2**0
    CONTENTS, READONLY
    13 .note 000013c4 000013c4 000013c4 0011de3c 2**0
    CONTENTS, READONLY

    However the FileOffset of the .text.lock is not 00101000 as in your
    example but 2**0
    CONTENTS, READONLY
    2 .rodata 00017cbd c01c0cd4 c01c0cd4 000c0cd4 2**2
    CONTENTS, ALLOC, LOAD, READONLY, DATA
    3 .kstrtab 00002f94 c01d8991 c01d8991 000d8991 2**0
    CONTENTS, ALLOC, LOAD, READONLY, DATA
    4 __ex_table 000016e8 c01db930 c01db930 000db930 2**2
    CONTENTS, ALLOC, LOAD, READONLY, DATA
    5 __ksymtab 00000fb0 c01dd018 c01dd018 000dd018 2**2
    CONTENTS, ALLOC, LOAD, READONLY, DATA
    6 .data 000125c8 c01ddfd0 c01ddfd0 000ddfd0 2**4
    CONTENTS, ALLOC, LOAD, DATA
    7 .text.init 00006581 c01f1000 c01f1000 000f1000 2**2
    CONTENTS, ALLOC, LOAD, READONLY, CODE
    8 .data.init 0000007c c01f7584 c01f7584 000f7584 2**2
    CONTENTS, ALLOC, LOAD, DATA
    9 .bss 0003a990 c01f8000 c01f8000 000f8000 2**3
    ALLOC
    10 .stab 00014910 00000000 00000000 000f9210 2**2
    CONTENTS, READONLY, DEBUGGING
    11 .stabstr 0000ef58 00000000 00000000 0010db20 2**0
    CONTENTS, READONLY, DEBUGGING
    12 .comment 000013c4 00000000 00000000 0011ca78 2**0
    CONTENTS, READONLY
    13 .note 000013c4 000013c4 000013c4 0011de3c 2**0
    CONTENTS, READONLY

    However the FileOffset of the .text.lock is not 00101000 as in your
    example but 000f8000.

    > 1 .text.lock 00001223 c01c5a57 c01c5a57 00101000 2**0
    > CONTENTS, READONLY

    Does the

    : current->tss.cr3 = 00101000, %cr3 = 00101000

    of the crashlogs indicate that the .text.lock segment is searched
    there?

    Wolfgang
    (trying to have a clue ,-)

    --
    _/ _/ _/ _/ _/_/_/ . Wolfgang Wander HERMES Collaboration
    _/ _/ _/ _/ _/ . DESY Hamburg Email: Wolfgang.Wander@desy.de
    _/_/_/ _/_/_/ _/ . Notkestr. 85 Tel: +49 40 8998 4638 Fax: -4034
    _/_/_/ _/_/_/ _/_/_/ . 22603 Hamburg http://www-hermes.desy.de/wander.html


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