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 5571 5563 -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 3041 2972 -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.manda21@xxxxxxxxx>
Reviewed-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
---
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
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