linux-kernel - Re: [PATCH v5 4/9] x86/traps: Enable all exception handler callbacks early

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Message-ID: <20160403141041.GE19007@pd.tnic>
Date:	Sun, 3 Apr 2016 16:10:41 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andy Lutomirski <luto@...nel.org>, X86 ML <x86@...nel.org>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	KVM list <kvm@...r.kernel.org>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	xen-devel <Xen-devel@...ts.xen.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v5 4/9] x86/traps: Enable all exception handler callbacks
 early

On Sun, Apr 03, 2016 at 06:55:00AM -0700, Andy Lutomirski wrote:
> > No, please don't fail at early boot.
> >
> > Early boot is just about the *worst* situation to try to debug odd
> > failures, exactly since things like printk may not be reliable, and
> > things won't get logged etc.
> >
> > So particularly during early boot we should try as hard as possible
> > not to crash - even if it means not being able to log about a problem.
> > At least that way you have a hopefully working machine and can *maybe*
> > debug things.
> >
> 
> In this regard, at least, my patch is the right approach.  Calling the
> handler, whatever it is, is less likely to panic than refusing to call
> it.

Ok, good.

But can we pretty please document this whole situation, i.e., the
fact that we're trying really really hard not to fail early boot for
debuggability reasons - either in the commit message or better in the
code, for future reference. I think this is an important aspect to hold
down.

Thanks.

-- 
Regards/Gruss,
    Boris.

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