linux-kernel - Re: v4.10: kernel stack frame pointer .. has bad value (null)

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Date:   Thu, 9 Mar 2017 16:29:10 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Pavel Machek <pavel@....cz>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Andy Lutomirski <luto@...capital.net>,
        kernel list <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Andrew Lutomirski <luto@...nel.org>,
        Borislav Petkov <bp@...en8.de>,
        Brian Gerst <brgerst@...il.com>,
        Denys Vlasenko <dvlasenk@...hat.com>,
        Peter Anvin <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: v4.10: kernel stack frame pointer .. has bad value (null)

On Wed, Mar 08, 2017 at 10:22:53PM +0100, Pavel Machek wrote:
> 
> Well, I have fast CPUs, but most of the time they just compile
> stuff. Especially bisect is compile-heavy. I suspect going back to
> gcc-3.2 would bring me bigger advantages than CPU upgrade...
> 

But note that 3.2 compiles a distinctly different kernel from something
new and shiny. The kernel uses a lot of GCC features optimistically to
generate different code.

So if by some chance your error depends on one of the new features,
bisecting with some ancient compiler will not work.

And I cannot see that getting any better, only worse.