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Commit 30d7e0d4 authored by Alon Bar-Lev's avatar Alon Bar-Lev Committed by Linus Torvalds
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[PATCH] Dynamic kernel command-line: common 



Current implementation stores a static command-line buffer allocated to
COMMAND_LINE_SIZE size.  Most architectures stores two copies of this buffer,
one for future reference and one for parameter parsing.

Current kernel command-line size for most architecture is much too small for
module parameters, video settings, initramfs paramters and much more.  The
problem is that setting COMMAND_LINE_SIZE to a grater value, allocates static
buffers.

In order to allow a greater command-line size, these buffers should be
dynamically allocated or marked as init disposable buffers, so unused memory
can be released.

This patch renames the static saved_command_line variable into
boot_command_line adding __initdata attribute, so that it can be disposed
after initialization.  This rename is required so applications that use
saved_command_line will not be affected by this change.

It reintroduces saved_command_line as dynamically allocated buffer to match
the data in boot_command_line.

It also mark secondary command-line buffer as __initdata, and copies it to
dynamically allocated static_command_line buffer components may hold reference
to it after initialization.

This patch is for linux-2.6.20-rc4-mm1 and is divided to target each
architecture.  I could not check this in any architecture so please forgive me
if I got it wrong.

The per-architecture modification is very simple, use boot_command_line in
place of saved_command_line.  The common code is the change into dynamic
command-line.

This patch:

1. Rename saved_command_line into boot_command_line, mark as init
   disposable.

2. Add dynamic allocated saved_command_line.

3. Add dynamic allocated static_command_line.

4. During startup copy: boot_command_line into saved_command_line.  arch
   command_line into static_command_line.

5. Parse static_command_line and not arch command_line, so arch
   command_line may be freed.

Signed-off-by: default avatarAlon Bar-Lev <alon.barlev@gmail.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ian Molton <spyro@f2s.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Kazumoto Kojima <kkojima@rr.iij4u.or.jp>
Cc: Richard Curnow <rc@rc0.org.uk>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Miles Bader <uclinux-v850@lsi.nec.co.jp>
Cc: Chris Zankel <chris@zankel.net>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ff91691b

include/linux/init.h

+3 −2
Original line number Diff line number Diff line
@@ -67,7 +67,8 @@ extern initcall_t __con_initcall_start[], __con_initcall_end[]; 
extern initcall_t __security_initcall_start[], __security_initcall_end[];



/* Defined in init/main.c */

extern char saved_command_line[];

extern char __initdata boot_command_line[];

extern char *saved_command_line;

extern unsigned int reset_devices;



/* used by init/main.c */
@@ -164,7 +165,7 @@ struct obs_kernel_param { 
#define early_param(str, fn)					\

	__setup_param(str, fn, fn, 1)



/* Relies on saved_command_line being set */

/* Relies on boot_command_line being set */

void __init parse_early_param(void);

#endif /* __ASSEMBLY__ */

init/main.c

+24 −5
Original line number Diff line number Diff line
@@ -121,8 +121,12 @@ extern void time_init(void); 
void (*late_time_init)(void);

extern void softirq_init(void);



/* Untouched command line (eg. for /proc) saved by arch-specific code. */

char saved_command_line[COMMAND_LINE_SIZE];

/* Untouched command line saved by arch-specific code. */

char __initdata boot_command_line[COMMAND_LINE_SIZE];

/* Untouched saved command line (eg. for /proc) */

char *saved_command_line;

/* Command line for parameter parsing */

static char *static_command_line;



static char *execute_command;

static char *ramdisk_execute_command;
@@ -399,6 +403,20 @@ static void __init smp_init(void) 


#endif



/*

 * We need to store the untouched command line for future reference.

 * We also need to store the touched command line since the parameter

 * parsing is performed in place, and we should allow a component to

 * store reference of name/value for future reference.

 */

static void __init setup_command_line(char *command_line)

{

	saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);

	static_command_line = alloc_bootmem(strlen (command_line)+1);

	strcpy (saved_command_line, boot_command_line);

	strcpy (static_command_line, command_line);

}



/*

 * We need to finalize in a non-__init function or else race conditions

 * between the root thread and the init thread may cause start_kernel to
@@ -453,7 +471,7 @@ void __init parse_early_param(void) 
		return;



	/* All fall through to do_early_param. */

	strlcpy(tmp_cmdline, saved_command_line, COMMAND_LINE_SIZE);

	strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);

	parse_args("early options", tmp_cmdline, NULL, 0, do_early_param);

	done = 1;

}
@@ -503,6 +521,7 @@ asmlinkage void __init start_kernel(void) 
	printk(KERN_NOTICE);

	printk(linux_banner);

	setup_arch(&command_line);

	setup_command_line(command_line);

	unwind_setup();

	setup_per_cpu_areas();

	smp_prepare_boot_cpu();	/* arch-specific boot-cpu hooks */
@@ -520,9 +539,9 @@ asmlinkage void __init start_kernel(void) 
	preempt_disable();

	build_all_zonelists();

	page_alloc_init();

	printk(KERN_NOTICE "Kernel command line: %s\n", saved_command_line);

	printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);

	parse_early_param();

	parse_args("Booting kernel", command_line, __start___param,

	parse_args("Booting kernel", static_command_line, __start___param,

		   __stop___param - __start___param,

		   &unknown_bootoption);

	if (!irqs_disabled()) {