linux-kernel - Re: [PATCH] free initrds boot option

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Message-Id: <20061206163021.f434f09b.akpm@osdl.org>
Date:	Wed, 6 Dec 2006 16:30:21 -0800
From:	Andrew Morton <akpm@...l.org>
To:	Michael Neuling <mikey@...ling.org>
Cc:	linux-kernel@...r.kernel.org, H Peter Anvin <hpa@...or.com>,
	Al Viro <viro@....linux.org.uk>, fastboot@...ts.osdl.org
Subject: Re: [PATCH] free initrds boot option

On Thu, 07 Dec 2006 11:18:43 +1100
Michael Neuling <mikey@...ling.org> wrote:

> Add free_initrd= option to control freeing of initrd memory after
> extraction.  By default, free memory as previously.
> 
> Signed-off-by: Michael Neuling <mikey@...ling.org>
> ---
> Useful for kexec when you want to reuse the same initrd.  Testing on
> POWERPC with CPIOs 
> 
> --- linux-2.6-ozlabs.orig/init/initramfs.c
> +++ linux-2.6-ozlabs/init/initramfs.c
> @@ -487,6 +487,17 @@ static char * __init unpack_to_rootfs(ch
>  	return message;
>  }
>  
> +static int do_free_initrd = 1;
> +
> +int __init free_initrd_param(char *p)
> +{
> +	if (p && strncmp(p, "0", 1) == 0)
> +		do_free_initrd = 0;
> +
> +	return 0;
> +}
> +early_param("free_initrd", free_initrd_param);
> +
>  extern char __initramfs_start[], __initramfs_end[];
>  #ifdef CONFIG_BLK_DEV_INITRD
>  #include <linux/initrd.h>
> @@ -494,10 +505,13 @@ extern char __initramfs_start[], __initr
>  
>  static void __init free_initrd(void)
>  {
> -#ifdef CONFIG_KEXEC
>  	unsigned long crashk_start = (unsigned long)__va(crashk_res.start);
>  	unsigned long crashk_end   = (unsigned long)__va(crashk_res.end);
>  
> +	if (!do_free_initrd)
> +		goto skip;
> +
> +#ifdef CONFIG_KEXEC
>  	/*
>  	 * If the initrd region is overlapped with crashkernel reserved region,
>  	 * free only memory that is not part of crashkernel region.
> @@ -515,7 +529,7 @@ static void __init free_initrd(void)
>  	} else
>  #endif
>  		free_initrd_mem(initrd_start, initrd_end);
> -
> +skip:
>  	initrd_start = 0;
>  	initrd_end = 0;
>  }

I'd have thought that an option `retain_initrd' would make more sense.

Please always update Documentation/kernel-parameters.txt when adding boot
options.

-
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