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Re: [PATCH tracing/kprobes v2 1/5] tracing/kprobes: Rename special variables syntax
- From: Masami Hiramatsu <mhiramat at redhat dot com>
- To: Frederic Weisbecker <fweisbec at gmail dot com>
- Cc: rostedt at goodmis dot org, Ingo Molnar <mingo at elte dot hu>, lkml <linux-kernel at vger dot kernel dot org>, systemtap <systemtap at sources dot redhat dot com>, DLE <dle-develop at lists dot sourceforge dot net>, Thomas Gleixner <tglx at linutronix dot de>, Arnaldo Carvalho de Melo <acme at redhat dot com>, Mike Galbraith <efault at gmx dot de>, Paul Mackerras <paulus at samba dot org>, Peter Zijlstra <a dot p dot zijlstra at chello dot nl>, Christoph Hellwig <hch at infradead dot org>, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Jim Keniston <jkenisto at us dot ibm dot com>, "Frank Ch. Eigler" <fche at redhat dot com>
- Date: Tue, 06 Oct 2009 21:13:50 -0400
- Subject: Re: [PATCH tracing/kprobes v2 1/5] tracing/kprobes: Rename special variables syntax
- References: <20091002214834.30906.86502.stgit@dhcp-100-2-132.bos.redhat.com> <20091002214842.30906.49220.stgit@dhcp-100-2-132.bos.redhat.com> <20091003015444.GE4828@nowhere> <4AC830F0.2010003@redhat.com> <4ACA25D5.10703@redhat.com> <20091005192609.GB6071@nowhere> <1254787973.13160.195.camel@gandalf.stny.rr.com> <4ACB52F6.7020106@redhat.com> <20091006224755.GC11007@nowhere>
Frederic Weisbecker wrote:
> On Tue, Oct 06, 2009 at 10:23:50AM -0400, Masami Hiramatsu wrote:
>> OK, so here are syntax ideas
>>
>> * current syntax
>> <Ftrace>
>> - $sp_var
>> - %regs
>> - @symbol
>> <Perf>
>> - local_var
>
>
> This one looks good.
> And why not turning @symbol into symbol?
> Then it's up to perf probe to find the right
> target.
Hmm, one big reason for separating local_vars
and others is that I'd like to check whether
perf-probe needs debuginfo or not.
If there is no local_vars, we don't need to
parse debuginfo. Sometimes, it is useful just
for setting up probe points.
> And @ can be used for raw addresses?
Yeah, but @ can be shared with symbols and raw addresses.
If the first char is digit, it's not a symbol.:-)
And also, @symbol actually has its syntax rule.:-)
its real syntax is:
@[MODULE:]SYMBOL[+OFFSET]
or
@ADDRESS (0xNN (base 16) or NN (base 10))
Perhaps, since perf-probe has another syntax rule,
I don't want to confuse users. :-P
Thank you,
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division
e-mail: mhiramat@redhat.com