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Re: pthread_t ids of threads not showed by "thread info"
On Mon, 26 Apr 2010 10:38:09 +0200, Stefano Sabatini wrote:
> $ cd /usr/lib/debug/lib
> $ cd
> $ nm -S libpthread-2.10.2.so | grep __stack_user
> 00017160 00000008 b __GI___stack_user
> 00017160 00000008 b __stack_user
> $ nm -S libpthread-2.10.2.so | grep stack_used
> 0001511c 00000008 d stack_used
You should have DWARFs symbols. The ELF symbols are not enough for structures
derefencing.
readelf -wi /usr/lib/debug/lib64/libpthread.so.0.debug
[ formatted a bit ]
<1><9304>: Abbrev Number: 111 (DW_TAG_variable)
<9305> DW_AT_name : (indirect string, offset: 0x300b): __stack_user
<930f> DW_AT_type : <0x461b>
<9313> DW_AT_external : 1
<9314> DW_AT_location : 9 byte block: 3 80 b2 21 0 0 0 0 0 (DW_OP_addr: 21b280)
<1><461b>: Abbrev Number: 3 (DW_TAG_typedef)
<461c> DW_AT_name : (indirect string, offset: 0x7f8): list_t
<4622> DW_AT_type : <0x45f0>
<1><45f0>: Abbrev Number: 14 (DW_TAG_structure_type)
<45f1> DW_AT_name : (indirect string, offset: 0x2469): list_head
<45f5> DW_AT_byte_size : 16
<2><45fc>: Abbrev Number: 11 (DW_TAG_member)
<45fd> DW_AT_name : (indirect string, offset: 0x169d): next
<4603> DW_AT_type : <0x4615>
<4607> DW_AT_data_member_location: 0
<2><4608>: Abbrev Number: 11 (DW_TAG_member)
<4609> DW_AT_name : (indirect string, offset: 0x1303): prev
<460f> DW_AT_type : <0x4615>
<4613> DW_AT_data_member_location: 8
Anyway these symbols are not required for the right way of traversing this
list. For that purpose (as being used for native non-core `info threads') GDB
just calls functions provided by /lib64/libthread_db.so.1 . You can check glibc
sources for nptl_db/td_ta_thr_iter.c . nptl_db uses simple ELF symbols not
requiring the debuginfo files, like this one:
$ gdb -q -ex 'p *(int *)_thread_db_pthread_list' -ex q /lib64/libpthread.so.0
$1 = 128
> I'm currently stucked with this, I really cannot say if it is a
> problem with what I'm doing or with some debian specific issue.
If Debian GDB cannot find the symbols guessing Debian probably has more light
(smaller) debug info packages.
Regards,
Jan