[PATCH 1/3] kernel: Add a new config option to remove command line parsing
This patch introduces CONFIG_CMDLINE_PARSE option which conditionally compiles
the support for parsing kernel command line arguments. The corresponding
functions that actually do the parsing will be compiled out.
This is used when no parameters will be specified neither at compile time nor at
boot time.
Bloat-o-meter output (compared to the preivous version in which builtin cmdline
was also set to 'Y'):
add/remove: 0/8 grow/shrink: 0/6 up/down: 0/-3669 (-3669)
function old new delta
load_module 55715563 -8
parse_early_param 54 44 -10
parse_early_options 33 5 -28
initcall_level_names 32 - -32
kernel_init_freeable 413 360 -53
unknown_module_param_cb 60 - -60
setup_arch 30412972 -69
set_init_arg 73 - -73
repair_env_string 81 - -81
start_kernel 857 759 -98
do_early_param 117 --117
unknown_bootoption 366 --366
parse_args 626 --626
builtin_cmdline 2048 - -2048
Signed-off-by: Iulia Manda iulia.mand...@gmail.com
Reviewed-by: Josh Triplett j...@joshtriplett.org
---
arch/x86/Kconfig| 15 +++
include/linux/moduleparam.h | 14 ++
kernel/params.c | 2 ++
3 files changed, 31 insertions(+)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index c2fb8a8..f1e02ea 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2003,8 +2003,23 @@ config COMPAT_VDSO
If unsure, say N: if you are compiling your own kernel, you
are unlikely to be using a buggy version of glibc.
+config CMDLINE_PARSE
+ bool Enable support for command line parsing
+ default y
+ ---help---
+ With this option set to 'Y', kernel parameters, both the ones
+ passed at boot time and at compile time are parsed.
+
+ If you say no here, all the kernel parameters' values will be set
+ to their defaults at compile time, in order to make constant
+ folding possible.
+
+ Systems with no space constraints should leave this option set to
+ 'Y'.
+
config CMDLINE_BOOL
bool Built-in kernel command line
+ depends on CMDLINE_PARSE
---help---
Allow for specifying boot arguments to the kernel at
build time. On some systems (e.g. embedded ones), it is
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index 1c9effa..f97397c 100644
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -350,6 +350,7 @@ extern bool parameq(const char *name1, const char *name2);
*/
extern bool parameqn(const char *name1, const char *name2, size_t n);
+#ifdef CONFIG_CMDLINE_PARSE
/* Called on module insert or kernel boot */
extern char *parse_args(const char *name,
char *args,
@@ -359,6 +360,19 @@ extern char *parse_args(const char *name,
s16 level_max,
int (*unknown)(char *param, char *val,
const char *doing));
+#else
+static inline char *parse_args(const char *name,
+ char *args,
+ const struct kernel_param *params,
+ unsigned num,
+ s16 level_min,
+ s16 level_max,
+ int (*unknown)(char *param, char *val,
+ const char *doing))
+{
+return NULL;
+}
+#endif
/* Called by module remove. */
#ifdef CONFIG_SYSFS
diff --git a/kernel/params.c b/kernel/params.c
index 728e05b..d3bfe47 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -93,6 +93,7 @@ static void param_check_unsafe(const struct kernel_param *kp)
}
}
+#ifdef CONFIG_CMDLINE_PARSE
static int parse_one(char *param,
char *val,
const char *doing,
@@ -239,6 +240,7 @@ char *parse_args(const char *doing,
/* All parsed OK. */
return NULL;
}
+#endif
/* Lazy bastard, eh? */
#define STANDARD_PARAM_DEF(name, type, format, strtolfn) \
--
1.9.1
--
To unsubscribe from this list: send the line unsubscribe linux-embedded in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH 3/3] init: Set initcall_debug to a default value
Test the previously implemented macros on initcall_debug parameter, after
setting CONFIG_CMDLINE_PARSE to 'n'.
This change is a first example for how knowing the values of kernel parameters
at build time can allow GCC constant folding and result in an actually
relevant decrease in size. Other types of parameters also need to be handled.
Also, at the moment this would only work with default values. For being able
to change those defaults and still know their values at compile time, a
pre-compiled stand-alone parser should be run on those variables. This will be
discussed in a following patch.
The variable corresponding to initcall_debug kernel parameter is set by default
to false. Even though DEFINE_CORE_PARAM resumes to nothing when
CONFIG_CMDLINE_PARSE is not set, we need to use it in main.c so that it is
still defined when this option is 'y'.
Bloat-o-meter output:
add/remove: 0/3 grow/shrink: 0/9 up/down: 0/-385 (-385)
function old new delta
initcall_debug 1 - -1
pm_init 105 100 -5
__param_str_initcall_debug15 - -15
__param_initcall_debug16 - -16
syscore_suspend 247 224 -23
syscore_resume 175 152 -23
syscore_shutdown 80 55 -25
pci_fixup_device 235 198 -37
async_synchronize_cookie_domain 162 116 -46
async_run_entry_fn 178 127 -51
device_shutdown 256 204 -52
do_one_initcall 339 248 -91
Signed-off-by: Iulia Manda iulia.mand...@gmail.com
Reviewed-by: Josh Triplett j...@joshtriplett.org
---
include/linux/init.h | 3 ++-
init/main.c | 3 +--
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/linux/init.h b/include/linux/init.h
index 2df8e8d..d53f28d 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -3,6 +3,7 @@
#include linux/compiler.h
#include linux/types.h
+#include linux/params.h
/* These macros are used to mark some functions or
* initialized data (doesn't apply to uninitialized data)
@@ -155,7 +156,7 @@ int __init init_rootfs(void);
extern void (*late_time_init)(void);
-extern bool initcall_debug;
+DECLARE_CORE_PARAM(initcall_debug, false, bool);
#endif
diff --git a/init/main.c b/init/main.c
index 6f0f1c5f..85e9001 100644
--- a/init/main.c
+++ b/init/main.c
@@ -685,8 +685,7 @@ static void __init do_ctors(void)
#endif
}
-bool initcall_debug;
-core_param(initcall_debug, initcall_debug, bool, 0644);
+DEFINE_CORE_PARAM(initcall_debug, initcall_debug, false, bool, 0644);
#ifdef CONFIG_KALLSYMS
struct blacklist_entry {
--
1.9.1
--
To unsubscribe from this list: send the line unsubscribe linux-embedded in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH 2/3] linux: Add macros that define and declare a core_param variable
This patch introduces two macros for kernel command line arguments subsequently defined as core parameters: * DECLARE_CORE_PARAM - declares an extern variable in case CMDLINE_PARSE is set. In the other case it will make the variable a static constant asigned with a default value to enable constant folding; * DEFINE_CORE_PARAM - defines a core_param variable if CMDLINE_PARSE is set. In the other case it leaves the definition to be handled by DECLARE_CORE_PARAM macro. Introducing a new header file for the declaration of kernel parameters seemed to be the best option, because it solves the circular includes problem. Any other proposal that would be fit for this case is welcomed. Signed-off-by: Iulia Manda iulia.mand...@gmail.com Reviewed-by: Josh Triplett j...@joshtriplett.org --- include/linux/moduleparam.h | 9 + include/linux/params.h | 12 2 files changed, 21 insertions(+) create mode 100644 include/linux/params.h diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h index f97397c..17efa97 100644 --- a/include/linux/moduleparam.h +++ b/include/linux/moduleparam.h @@ -310,6 +310,15 @@ static inline void __kernel_param_unlock(void) #define core_param(name, var, type, perm) \ param_check_##type(name, (var)); \ __module_param_call(, name, param_ops_##type, var, perm, -1, 0) + +#ifdef CONFIG_CMDLINE_PARSE +#define DEFINE_CORE_PARAM(name, var, val, type, perm) \ +type var = val; \ +core_param(name, var, type, perm) +#else +#define DEFINE_CORE_PARAM(name, var, val, type, perm) +#endif + #endif /* !MODULE */ /** diff --git a/include/linux/params.h b/include/linux/params.h new file mode 100644 index 000..c1ee6ff --- /dev/null +++ b/include/linux/params.h @@ -0,0 +1,12 @@ +#ifndef _LINUX_PARAMS_H +#define _LINUX_PARAMS_H + +#ifdef CONFIG_CMDLINE_PARSE +#define DECLARE_CORE_PARAM(var, val, type) \ +extern type var +#else +#define DECLARE_CORE_PARAM(var, val, type) \ +static const type var = val +#endif + +#endif /* _LINUX_PARAMS_H */ -- 1.9.1 -- To unsubscribe from this list: send the line unsubscribe linux-embedded in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
