Pra*_*kar 10 arm linux-kernel u-boot
我想atag在U-Boot和Linux内核中添加自定义变量.
我怎样才能实现这一目标？
是否有任何步骤添加ATAG变量U-Boot和Linux？
最新的 Linux 内核正试图用设备树来淘汰ATAGS。但是，setup.h文件定义了不同的ATAG值和结构。要解析这些，你需要添加类似的东西，
static int __init parse_tag_custom(const struct tag *tag)
{
if (tag->hdr.size > CUSTOM_SIZE) {
/* Use, storing or acting on passed values */
tag->u.custom;
}
return 0;
}
__tagtable(ATAG_CUSTOM, parse_tag_custom);
如atags_parse.c 中所示。当然，您需要将这些添加到setup.h 中的值中。
在大多数情况下，u-boot 的定义可能较少，它通过内核命令行传递参数，因为这不是特定于ARM 的。甲命令参数或设备的树可能是优选的方法。如果您举例说明您需要哪种类型的配置，那么有人可能会提供更好的指导。
小智 5
需要U-Boot更改:
A. Make sure the CONFIG_CMDLINE_TAG/CONFIG_SETUP_MEMORY_TAGS/CONFIG_INITRD_TAG are defined in you project definition header file ( u-boot/include/configs/am335x_evm.h ), and we can add our own tag here, eg. CONFIG_CUSTOM_TAG.
B. Add the structure definition you wanna append w/ ATAG in u-boot/include/asm-arm/setup.h, eg.
#define ATAG_CUSTOM 0x5441000a
struct tag_custom{
unsigned char mac_addr[6];
};
C. Add the struct at the tail of "u"...
struct tag {
struct tag_header hdr;
union {
struct tag_core core;
struct tag_mem32 mem;
struct tag_videotext videotext;
struct tag_ramdisk ramdisk;
struct tag_initrd initrd;
struct tag_serialnr serialnr;
struct tag_revision revision;
struct tag_videolfb videolfb;
struct tag_cmdline cmdline;
/*
* Acorn specific
*/
struct tag_acorn acorn;
/*
* DC21285 specific
*/
struct tag_memclk memclk;
/****** INFOTECH Custom TAG ********/
struct tag_custom custom;
} u;
};
D. Add implementation code in lib_arm/bootm.c:
static void setup_custom_tag(bd_t *bd);
static void setup_custom_tag(bd_t *bd) {
params->hdr.tag = ATAG_CUSTOM;
params->hdr.size = tag_size (tag_macaddr);
params->u.custom.cmd =0;
params = tag_next (params);
}
E. Add "#ifdef CONFIG_CUSTOM_TAG / #endif" at every place you change the code.
F. Done of U-Boot modification.
需要Linux更改:
A.在linux/arch/arm/kernel/setup.c中添加解析标记代码:
int cmd;
static int __init parse_tag_custom(const struct tag *tag){
printk("u.custom.cmd=%d\n",tag->u.custom.cmd);
return 0;
}
__tagtable(ATAG_MACADDR, parse_tag_custom);
B.在linux/include/asm-arm/setup.h中将结构声明添加为U-Boot:
#define ATAG_MACADDR 0x5441000a
struct tag_custom {
int cmd;
};
C.在"你"的尾部添加结构...
struct tag {
struct tag_header hdr;
union {
struct tag_core core;
struct tag_mem32 mem;
struct tag_videotext videotext;
struct tag_ramdisk ramdisk;
struct tag_initrd initrd;
struct tag_serialnr serialnr;
struct tag_revision revision;
struct tag_videolfb videolfb;
struct tag_cmdline cmdline;
/*
* Acorn specific
*/
struct tag_acorn acorn;
/*
* DC21285 specific
*/
struct tag_memclk memclk;
/* Add Infotech custom tag */
struct tag_custom custom;
} u;
};
D.完成内核部分.
按照这个程序，
为了实现这个目标，有两个部分需要修改。一个是U-Boot，另一个是Linux 内核。
1. U-Boot changes required :
A. Make sure the CONFIG_CMDLINE_TAG/CONFIG_SETUP_MEMORY_TAGS/CONFIG_INITRD_TAG are defined in you project definition header file ( u-boot/include/configs/am335x_evm.h ), and we can add our own tag here, eg. CONFIG_CUSTOM_TAG.
B. Add the structure definition you wanna append w/ ATAG in u-boot/include/asm-arm/setup.h, eg.
#define ATAG_CUSTOM 0x5441000a
struct tag_custom{
unsigned char mac_addr[6];
};
C. Add the struct at the tail of "u"...
struct tag {
struct tag_header hdr;
union {
struct tag_core core;
struct tag_mem32 mem;
struct tag_videotext videotext;
struct tag_ramdisk ramdisk;
struct tag_initrd initrd;
struct tag_serialnr serialnr;
struct tag_revision revision;
struct tag_videolfb videolfb;
struct tag_cmdline cmdline;
/*
* Acorn specific
*/
struct tag_acorn acorn;
/*
* DC21285 specific
*/
struct tag_memclk memclk;
/****** INFOTECH Custom TAG ********/
struct tag_custom custom;
} u;
};
D. Add implementation code in lib_arm/bootm.c:
static void setup_custom_tag(bd_t *bd);
static void setup_custom_tag(bd_t *bd) {
params->hdr.tag = ATAG_CUSTOM;
params->hdr.size = tag_size (tag_macaddr);
params->u.custom.cmd =0;
params = tag_next (params);
}
E. Add "#ifdef CONFIG_CUSTOM_TAG / #endif" at every place you change the code.
F. Done of U-Boot modification.
2. Linux Changes required:
A. Add parse tag code in linux/arch/arm/kernel/setup.c:
int cmd;
static int __init parse_tag_custom(const struct tag *tag){
printk("u.custom.cmd=%d\n",tag->u.custom.cmd);
return 0;
}
__tagtable(ATAG_MACADDR, parse_tag_custom);
B. Add the structure declaration as U-Boot did in linux/include/asm-arm/setup.h:
#define ATAG_MACADDR 0x5441000a
struct tag_custom {
int cmd;
};
C. Add the struct at the tail of "u"...
struct tag {
struct tag_header hdr;
union {
struct tag_core core;
struct tag_mem32 mem;
struct tag_videotext videotext;
struct tag_ramdisk ramdisk;
struct tag_initrd initrd;
struct tag_serialnr serialnr;
struct tag_revision revision;
struct tag_videolfb videolfb;
struct tag_cmdline cmdline;
/*
* Acorn specific
*/
struct tag_acorn acorn;
/*
* DC21285 specific
*/
struct tag_memclk memclk;
/* Add Infotech custom tag */
struct tag_custom custom;
} u;
};
D. Done w/ Kernel parts.