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Date:      Tue, 12 Dec 2017 09:32:05 -0800 (PST)
From:      "Rodney W. Grimes" <freebsd@pdx.rh.CN85.dnsmgr.net>
To:        Andriy Gapon <avg@freebsd.org>
Cc:        rgrimes@freebsd.org, Eugene Grosbein <eugen@grosbein.net>, Don Lewis <truckman@freebsd.org>, Alexey Dokuchaev <danfe@freebsd.org>, Konstantin Belousov <kostikbel@gmail.com>, svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Conrad Meyer <cem@freebsd.org>
Subject:   Re: svn commit: r326758 - in head/sys/i386: conf include
Message-ID:  <201712121732.vBCHW5UR087312@pdx.rh.CN85.dnsmgr.net>
In-Reply-To: <9484a39c-21f1-9174-11ce-54088c3f6099@FreeBSD.org>

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> On 12/12/2017 19:01, Rodney W. Grimes wrote:
> > We should probably start looking for those, something someone who is
> > offerring help but doesnt know what they might be good at, but can
> > read C code.  They could be utililized t simply scan through the
> > code looking for this type of thing and bring it to the attention
> > of a area of expertise commiter.
> 
> By the way, there are tools that can analyze binary code (e.g. a kernel binary
> or a module) and determine stack requirements of each function.  I think that
> debug symbols might be required too.

That would be an even better first start, even if it just could
tell us what the local var stack space request of each function
was that might point out some easly low hanging fruit.

Can it also tell us how big the call frame is?

> 
> I am not sure if there are tools that can analyze stack requirements for
> possible call chains rather than individual functions.

Call graphs can be used to find deep chains.  Combine the above
with a call graph and we should be able to come up with some
data.

This also sounds like a good caniate for GSOC, creation
of a call graph with static analysis of local variable size +
call frame size requirements as a O(1) stack space estimator.


-- 
Rod Grimes                                                 rgrimes@freebsd.org



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