linux-kernel - Re: [PATCH v5 3/9] x86/head: Move early exception panic code into early_fixup

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Date:	Mon, 4 Apr 2016 08:36:35 -0700
From:	Arjan van de Ven <arjan@...ux.intel.com>
To:	Andy Lutomirski <luto@...capital.net>, Jan Kara <jack@...e.cz>
Cc:	Paolo Bonzini <pbonzini@...hat.com>,
	xen-devel <Xen-devel@...ts.xen.org>,
	Borislav Petkov <bp@...en8.de>, X86 ML <x86@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Petr Mladek <pmladek@...e.cz>, KVM list <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH v5 3/9] x86/head: Move early exception panic code into
 early_fixup_exception

On 4/4/2016 8:32 AM, Andy Lutomirski wrote:
>
> Adding locking would be easy enough, wouldn't it?
>
> But do any platforms really boot a second CPU before switching to real
> printk?  Given that I see all the smpboot stuff in dmesg, I guess real
> printk happens first.  I admit I haven't actually checked.

adding locking also makes things more fragile in terms of getting the last thing out
before you go down in flaming death....

until it's a proven problem, this early, get the message out at all is more important
than getting it out perfectly, sometimes.