basic questions to strace

Lentes, Bernd bernd.lentes at
Fri Oct 7 16:08:41 UTC 2016

----- On Oct 7, 2016, at 3:59 PM, Eugene Syromyatnikov evgsyr at wrote:

>> Starting a process give me this error in the log:
>> traps: nsrexecd[12162] general protection ip:7f085e4cb960 sp:7f085a4e9278
>> error:0 in[7f085e4b9000+18000]
>> It seems that the kernel is stopping the process because of ... what with a
>> signal.
> For debugging segmentation faults, i'd recommend installing debuginfo packages,
> enabling core file saving and then checking them out with gdb, usually it allows
> pinpointing problem rather quickly.

Is that a segmentation fault ?

> Clone is rather comprehensive syscall by means that it is used for several
> different tasks. Which arguments are used depends on flags provided, and strace
> prints only arguments actually used (for brevity, i suppose). Syscall arguments
> parsing for clone call is done as follows (clone.c in strace source):

Ah. So clone is called with all arguments but strace shows just the relevant ?
Does strace have this behaviour also with other system calls ?

>> What means the return code 13025 ? I didn't find anything about it in the net.
>> Is there where i can get further information ?
> On success, clone returns ID of the child process to the parent. You can check
> it out in the "RETURN VALUE" section of the manual.

Sorry, i didn't read completely. Because the return code was != 0, i thought it's an error code.

>> I installed the kernel sources and searched for a file like clone.h or clone.c,
>> but didn't find anything.
> Please check out kernel/fork.c file in kernel tree, it contains
> SYSCALL_DEFINE[56](clone, ...), which calls _do_fork().

I installed the debian-kerbel via apt.
But it didn't install it completely, just downloaded a tar which i need to extract manually.
Why do i have a package management ?


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