linux-kernel - Re: [V4 PATCH 4/4] x86/apic: Introduce noextnmi boot option

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Message-ID: <20151005101431.GC23259@nazgul.tnic>
Date:	Mon, 5 Oct 2015 12:14:31 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	河合英宏 / KAWAI，HIDEHIRO 
	<hidehiro.kawai.ez@...achi.com>
Cc:	'Peter Zijlstra' <peterz@...radead.org>,
	Jonathan Corbet <corbet@....net>,
	Ingo Molnar <mingo@...nel.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Vivek Goyal <vgoyal@...hat.com>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>,
	"kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Michal Hocko <mhocko@...nel.org>,
	Ingo Molnar <mingo@...hat.com>,
	平松雅巳 / HIRAMATU，MASAMI 
	<masami.hiramatsu.pt@...achi.com>
Subject: Re: [V4 PATCH 4/4] x86/apic: Introduce noextnmi boot option

On Mon, Oct 05, 2015 at 09:21:02AM +0000, 河合英宏 / KAWAI，HIDEHIRO wrote:
> So, the problem for you is that "noextnmi" option is visible and effective
> in the first kernel, isn't it?

No, such an option shouldn't exist at all. You should be passing
information *in* *a* *different* *manner* to the kdump kernel - not with
a kernel command line option.

I get the feeling I'm starting to sound like a broken record on this
mail thread... :-(

One other thing we could probably try to do is use boot_params which
is, IIUC, passed to the second kernel. So we can add another bit to
boot_params.hdr.loadflags or so and use that. Or something similar.

Not particularly crazy about it but it is still much better than a
command line param...

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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