linux-kernel - Re: [PATCH 2/5] objtool: Combine '--backtrace' with '--verbose'

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Date:   Wed, 29 Mar 2023 09:25:53 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Josh Poimboeuf <jpoimboe@...nel.org>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Miroslav Benes <mbenes@...e.cz>
Subject: Re: [PATCH 2/5] objtool: Combine '--backtrace' with '--verbose'

On Tue, Mar 28, 2023 at 01:19:21PM -0700, Josh Poimboeuf wrote:
> On Tue, Mar 28, 2023 at 10:07:43AM +0200, Peter Zijlstra wrote:
> > On Mon, Mar 27, 2023 at 09:00:45AM -0700, Josh Poimboeuf wrote:
> > > Get rid of the '--backtrace' option, instead including that
> > > functionality in '--verbose'.  This makes it easy to gather all the
> > > information needed for diagnosing objtool warnings.
> > 
> > Hurmm.. can't we have verbose imply backtrace but keep the separate
> > option? I'm not sure if I always want the objdump thing -- esp with
> > multiple warnings on vmlinux that's going to be really slow -- better to
> > dump the whole of vmlinux.o once at the end.
> 
> That's a good point, vmlinux would be unbearable for multiple warnings.
> 
> We could accumulate a list of affected functions and then supply that to
> objdump-func.sh at the end and dump them all at the same time.
> 
> objdump-func.sh would need to be changed to look for multiple funcs at
> once.
> 
> If I do that, do you still want the separate backtrace option?

For now, lets keep the orthogonal options -- we can always remove it
later if we find they go unused. This automagic stuff is going to take a
bit of getting used to I recon ;-)