linux-kernel - Re: [PATCH] init: Warn on non-existent rdinit

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Date:	Thu, 05 Jan 2012 22:45:29 +0100
From:	Richard Weinberger <richard@....at>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
CC:	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	a.p.zijlstra@...llo.nl, mingo@...e.hu, xiyou.wangcong@...il.com
Subject: Re: [PATCH] init: Warn on non-existent rdinit

Am 05.01.2012 21:53, schrieb Eric W. Biederman:
> Richard Weinberger <richard@....at> writes:
> 
>> Such a warning would have saved me some time...
>> Hopefully this printk() saves someone else's time. :-)
> 
> The warning is wrong if you are not using an initramfs or an initial
> ramdisk.

Gnah, you're so right.
I did not test it without a ramdisk.

> I expect what you want is something like:
> 
> diff --git a/init/main.c b/init/main.c
> index 217ed23..8d53d28 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -830,10 +830,11 @@ static int __init kernel_init(void * unused)
>          * the work
>          */
>  
> -       if (!ramdisk_execute_command)
> +       if (!ramdisk_execute_command &&
> +           (sys_access((const char __user *)"/init", 0) == 0))
>                 ramdisk_execute_command = "/init";
>  
> -       if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
> +       if (!ramdisk_execute_command) {
>                 ramdisk_execute_command = NULL;
>                 prepare_namespace();
>         }

Why ramdisk_execute_command = NULL; in the !ramdisk_execute_command case?

> 
> That way we don't clear ramdisk_execute_command if it was set and
> we complain if we attempt exec the ramdisk_execute_command.

If "/init" does not exist we still don't get a warning.

Thanks,
//richard



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