Re: Linux Kernel GDB tracepoint module 2010-8-30 release
From: Hui Zhu
Date: Sat Sep 04 2010 - 12:34:47 EST
Hi Frank,
I try systemtrap but got some error:
On Fri, Sep 3, 2010 at 22:05, Frank Ch. Eigler <fche@xxxxxxxxxx> wrote:
>
> Steven <mqyoung@xxxxxxxxx> writes:
>
>> [...]
>> (gdb) trace vfs_readdir
>> Tracepoint 3 at 0xc1175690: file fs/readdir.c, line 23.
>> (gdb) actions
>> Enter actions for tracepoint 3, one per line.
>> End with a line saying just "end".
>> > collect jiffies_64
>> > collect *file
>> > end
>
> By the way, the systemtap equivalent would be:
>
> #! /usr/bin/stap -g
> probe kernel.function("vfs_readdir") {
> println(%{ jiffies_64 %})
> println($file$)
> }
parse error: expected literal string or number
saw: embedded-code at ./1.sh:3:14
source: println(%{ jiffies_64 %})
^
parse error: expected statement
saw: ./1.sh EOF
2 parse error(s).
Pass 1: parse failed. Try again with another '--vp 1' option.
>
>
>> 2) I can not collect local variable, despite I rebuild the kernel with
>> -O0 optimization option. what is the problem? Many thanks
>> -------------------------------------------------------------------
>> (gdb) trace fs/readdir.c:29
>> Tracepoint 2 at 0xc11756ca: file fs/readdir.c, line 29.
>> (gdb) actions
>> Enter actions for tracepoint 2, one per line.
>> End with a line saying just "end".
>> > collect res
>> > end
>
>
> #! /usr/bin/stap
> probe kernel.statement("*@fs/readdir.c:29") {
> println($res)
> }
>
semantic error: not accessible at this address: identifier '$res' at ./1.sh:3:14
source: println($res)
^
Pass 2: analysis failed. Try again with another '--vp 01' option.
[1]+ Done gedit 1.sh
Could you help me with it?
Thanks,
Hui
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