linux-kernel - Re: [PATCH v5] init: Disable defaults if init= fails

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Date:	Tue, 30 Sep 2014 21:53:56 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Rob Landley <rob@...dley.net>
Cc:	frowand.list@...il.com, Andrew Morton <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Chuck Ebbert <cebbert.lkml@...il.com>,
	Randy Dunlap <rdunlap@...radead.org>,
	Shuah Khan <shuah.kh@...sung.com>,
	Rusty Russell <rusty@...tcorp.com.au>
Subject: Re: [PATCH v5] init: Disable defaults if init= fails

On Tue, Sep 30, 2014 at 8:16 PM, Rob Landley <rob@...dley.net> wrote:
> On 09/30/14 20:52, Frank Rowand wrote:
>> On 9/30/2014 5:58 PM, Rob Landley wrote:
>>> If you're going to argue that it should "default y", that's a defensible
>>> choice. But please don't argue for kernel config symbols with a negative
>>> meaning or we'll start having allyesconfig_n brain damage too...
>>
>> Yes, "default y" is a valid answer to my request.
>
> Works for me.
>
>>>> Instead of using a config option, would adding another kernel
>>>> command line option, such as 'init_fail_is_fatal', work for
>>>> your needs?
>>>
>>> That was the previous series of patches you ignored, which added code so
>>> you can provide _extra_ kernel commands to tell it _not_ to do stuff.
>>> The patches did not generate noticeable enthusiasm.
>>
>> But there also was not a strong push back either.  Just Chuck's suggestion
>> of an alternate syntax, and your suggestion of instead using a config
>> option (and possibly immediately deprecating the config option).
>>
>> You could as easily frame the argument that the added code was to
>> tell the kernel to "_do_ stuff" (panic) instead of "_not_ do stuff".
>> But that is just semantics on my part; whatever.
>>
>> I thought the general trend was to try to avoid adding config options.
>> The strictinit method seems fine to me.
>
> Embedded guys care:
>
> http://elinux.org/Linux_Tiny
>
> http://lkml.iu.edu//hypermail/linux/kernel/1409.2/03763.html
>
>>>> I have a feeling this has already been proposed,
>>>> as the 'strictinit' option mentioned in the changes from v3
>>>> below might be the same concept?
>>>
>>> That was it, yes.
>>>
>>> Having to get your kernel config right (and your kernel command line
>>> right) in order for your system to boot is not really a new concept, is
>>> it? You can still specify "init=/bin/sh" if you want that. (I do it all
>>> the time when I need to edit a system I haven't bothered to look up the
>>> root password to.)
>>
>> Yes, of course I can.  So it falls back to personal preference (as I said,
>> I like that some failed boots will drop into a shell without having to
>> change the kernel command line).
>
> The config option lets it do that. Default Y preserves the old behavior.

I significantly prefer default N.  Scripts that play with init= really
don't want the fallback, and I can imagine contexts in which it could
be a security problem.

--Andy
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