linux-kernel - Re: [PATCH] x86/intel/quark: Remove lock bit around kernel IMR

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Message-ID: <CAHp75VfYBSz=-BfzYkPMvBooomZUgDGR8bkmrEVOYiqb=6z3qQ@mail.gmail.com>
Date:	Fri, 22 Jan 2016 14:11:30 +0200
From:	Andy Shevchenko <andy.shevchenko@...il.com>
To:	"Bryan O'Donoghue" <pure.logic@...us-software.ie>
Cc:	"x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	stable@...r.kernel.org
Subject: Re: [PATCH] x86/intel/quark: Remove lock bit around kernel IMR

On Fri, Jan 22, 2016 at 1:08 PM, Bryan O'Donoghue
<pure.logic@...us-software.ie> wrote:
> On Thu, 2016-01-21 at 20:44 +0200, Andy Shevchenko wrote:
>> On Thu, Jan 21, 2016 at 4:05 PM, Bryan O'Donoghue
>> <pure.logic@...us-software.ie> wrote:

[]

>> > The solution to this situation is to keep the kernel .text section
>> > IMR lock
>> > bit false. This means that a subsequent kernel will boot and can
>> > tear-down
>> > an existing IMR, while still setting up an IMR around its own .text
>> > section.
>> >
>>
>> Like I said you privately it would be nice to have a knob how to
>> behave.
>
> Ok - that can work. The default ought to be !locked and we can
> parametrize a different behaviour.
>
>
>> My idea is to provide kernel command line imr= and supply imr=lock
>> when user wants to boot kernel locked.
>
> Agreed.
>
>>
>> Optionally: add a warning if imr=lock and kernel build with kexec
>> that
>> might bring issues
>
> This makes sense.
>
>> Optionally: add a kernel config option to boot always in locked mode
>> (should depend on !KEXEC)
>
> Meh. You can still force the state you want with the parameter though.
> I reckon we should skip this change for now.

OK!

P.S. Please, use my @linux.intel.com address in the tags.

-- 
With Best Regards,
Andy Shevchenko