Re: RAS trace event proto

[Borislav Petkov <bp@amd64.org>]

On Mon, Feb 20, 2012 at 08:14:28PM -0500, Steven Rostedt wrote:
> On Mon, 2012-02-20 at 15:59 +0100, Borislav Petkov wrote:
> 
> > * I'd like to have conditional printk-ing in trace_mce_record depending
> > on the TP args, Steve probably knows what can be done:
> 
> /me is confused :-)

Yeah, sorry. I'll explain to you in more detail when you get over here
next month :-).

> > 
> > @Steven:
> > 
> > I'd like to do the following:
> > 
> > 	TP_printk("%s, ARG1: %d, ARG2: %c ...", str1, arg1, arg2)
> > 
> > and have it print only the first arg, i.e. the string and drop the rest
> > of the args while still doing the TP_fast_assign into the ring buffer
> > and carrying the stuff to its consumers. Background is that I want to
> > dump the decoded string of a hardware error, if it is decoded, but carry
> > the MCE info to userspace and only dump the fields of the MCE if I
> > haven't managed to decode it, i.e. str1 == "".
> > 
> > So, my question is, can I do something like:
> > 
> > 	TP_printk("%s, ARG1: %d, ARG2: %c ...", __print_conditional(str1, arg1, arg2))
> 
> You want to affect the output of ftrace?
> 
> perf and even trace-cmd do the parsing later and can be overridden.
> Well, perf can be when we finally get it to use the updated trace-cmd
> parser.

Right, that's another possibility. I simply didn't want to burden the
ring buffer with useless stuff we aren't going to use but I guess a
couple of tens of bytes aren't the world :)

Thanks.

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Boris.

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