Subject: Re: [x86-tip] RSDP changes converted i4790 box SMP -> UP
To: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>,
        Mike Galbraith <mgalbraith@suse.de>,
        LKML <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>
References: <20180111133723.d7x3sekanz5jhut2@gmail.com>
 <1515682631.16805.3.camel@suse.de>
 <20180111150331.7zzkd7awdxele54b@gmail.com>
 <20180111151044.GC6176@hirez.programming.kicks-ass.net>
 <1515694412.7054.10.camel@suse.de> <1515731128.10188.32.camel@suse.de>
 <20180112131144.bkopj2ooslwdyvoz@gmail.com>
 <0af5f083-b659-6c67-1ceb-a2bf9108c879@suse.com>
 <20180115145615.m54ewqg7vmvp4akj@pd.tnic>
 <b2a941a3-ff75-d57a-6dac-9a91fb0f4c31@suse.com>
 <20180115153243.3wst57a2fqin2h37@gmail.com>
From: Juergen Gross <jgross@suse.com>
Message-ID: <c4b9a536-d889-4429-76a5-a9fdd5f6234b@suse.com>
Date: Mon, 15 Jan 2018 16:40:32 +0100
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On 15/01/18 16:32, Ingo Molnar wrote:
> 
> * Juergen Gross <jgross@suse.com> wrote:
> 
>> On 15/01/18 15:56, Borislav Petkov wrote:
>>> On Mon, Jan 15, 2018 at 03:52:25PM +0100, Juergen Gross wrote:
>>>> Ingo, with my finding that above boot failure is related to a bug in
>>>> openSUSE's grub2 (I've verified it soesn't exist in upstream grub2),
>>>
>>> The box I'm seeing this on has SLES12-SP2 grub:
>>>
>>> Version        : 2.02~beta2-115.9.1
>>>
>>> Does it have the same bug?
>>
>> The patch introducing this problem is from 2012. So I guess: yes.
> 
> I suspect this makes it a widespread, unintended ABI. Can we detect and somehow avoid it?
> 
> The boot protocol ABI sucks if it's fragile against such mistakes.

Well, copying sizeof(setup_header) into grub2 and then coyping back just
1024 bytes is plain wrong. It is a miracle nothing broke up to now.


Juergen