Hi all,
I have asked before few weeks about tracing the execution of the
kernel or debugging it. Unfortunately, I faced some problems in using Kgdb,
especially that the patch was not successful on my redhat 7.3.
Whatever, lets say that kgdb worked successfully, how can I trace the
execution of ?a specific system call? (lets say printf), so I can see how it
works internally. Is there any other utility for that? How can I do that
with kgdb?
Thanx for your help in advance.
Yours,
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On Sun, 6 Jul 2003, Auge Mike wrote:
> Hi all,
>
> I have asked before few weeks about tracing the execution of the
> kernel or debugging it. Unfortunately, I faced some problems in using Kgdb,
> especially that the patch was not successful on my redhat 7.3.
> Whatever, lets say that kgdb worked successfully, how can I trace the
> execution of ?a specific system call? (lets say printf), so I can see how it
> works internally. Is there any other utility for that? How can I do that
> with kgdb?
>
> Thanx for your help in advance.
>
> Yours,
printf() is not a system call. It is some procedure within the
'C' runtime library. Eventually, that library makes a call to
write() which is a kernel system call. You can use strace to see
the execution of all the system calls.
If you want to single-step through the 'C' runtime library, you
need to get their sources and compile them with the '-g' parameter
(for debugging). I don't know why you would want to do that, because
you would then have the sources so you can actually read the source
of what happens with a particular call.
Cheers,
Dick Johnson
Penguin : Linux version 2.4.20 on an i686 machine (797.90 BogoMips).
Why is the government concerned about the lunatic fringe? Think about it.
From: "Auge Mike"
To: [email protected]
Subject: Debugging , Tracing...
On Sun, 06 Jul 2003 23:48:17 +0400, Auge Mike wrote:
>Hi all,
> I have asked before few weeks about tracing the
>execution of the
>kernel or debugging it. Unfortunately, I faced some
>problems in using Kgdb,
>especially that the patch was not successful on my
>redhat 7.3.
Hi, Auge. I think that the kernel execution cannot be
debugged nor traced by gdb (kgdb is just a frontend
for the GNU DeBugger), it can be used to trace/debug
the execution of any other program, including modules.
> Whatever, lets say that kgdb worked
>successfully, how can I trace the
>execution of ?a specific system call? (lets say
>printf), so I can see how it
>works internally. Is there any other utility for
>that? How can I do that
>with kgdb?
Other thing, printf() is not a system call, you use
write() (syscall #4) for printing things in screen.
A recommendation: don't use gdb or kgdb for tracing
programs execution, use "strace [program] [arguments]"
in your console, instead. GDB is useful for debugging
things, like when a program received a SIGSEGV (it
generates a coredump) in a file "core", and you can
debug it for searching the error that caused that
signal.
Strace is a tool that you use for tracing programs
syscalls during it execution.
I hope this will be useful for you.
Regards,
Slack
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