高通平臺在lk裡識別的屏之後，會通過cmdline向核心傳遞引數

1 cat /proc/cmdline

mdss_mdp.panel=1:dsi:0:qcom,mdss_dsi_nt35532_fhd_video:1:none:cfg:single_dsi 2 drivers\video\msm\mdss\Mdss_mdp.c 在這個函式中用module_param_string來註冊引數

module_param_string(panel, mdss_mdp_panel, MDSS_MAX_PANEL_LEN, 0);

展開這個巨集定義

#define module_param_string(name, string, len, perm)			\
	static const struct kparam_string __param_string_##name		\
		= { len, string };					\
	__module_param_call(MODULE_PARAM_PREFIX, name,			\
			    &param_ops_string,				\
			    .str = &__param_string_##name, perm, -1, 0);\
	__MODULE_PARM_TYPE(name, "string")
 

__module_param_call的巨集定義為

#define __module_param_call(prefix, name, ops, arg, perm, level, flags)	\
	/* Default value instead of permissions? */			\
	static const char __param_str_##name[] = prefix #name; \
	static struct kernel_param __moduleparam_const __param_##name	\
	__used								\
    __attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) \
	= { __param_str_##name, ops, VERIFY_OCTAL_PERMISSIONS(perm),	\
	    level, flags, { arg } }
 

根據這些巨集，最終展開的為

static const char __param_str_panel[] = MODULE_PARAM_PREFIX panel; \
static struct kernel_param __moduleparam_const __param_panel	\
	__used	__attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) = {
.name  = __param_str_panel, 
.ops   = ¶m_ops_string, 
.perm  = VERIFY_OCTAL_PERMISSIONS(0),	
.level = -1, 
.flags = 0,
.str = &__param_string_panel }
 

kernel連線時會將param放到_param段中 MODULE_PARAM_PREFIX的巨集定義為

#ifdef MODULE
#define MODULE_PARAM_PREFIX /* empty */
#else
#define MODULE_PARAM_PREFIX KBUILD_MODNAME "."
#endif

是模組編譯的為空，不是模組編譯的話為 "模組名."
檢視Makefile

obj-$(CONFIG_FB_MSM_MDSS) += mdss-mdp.o

可知模組名為mdss-mdp 所以kernel傳引數的時候，引數名為 mdss-mdp.panel 3 kernel對cmdline的解析 請參考http://blog.csdn.net/skyflying2012/article/details/41142801