我想在U-Boot和Linux内核中添加自定义的atag变量
我怎样才能做到这一点？
是否有任何程序可以在ATAG和U-Boot中添加Linux变量？
答案 0 :(得分：5)
需要更改U-Boot：
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：
一个。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中。在linux / include / asm-arm / setup.h中添加结构声明为U-Boot：
#define ATAG_MACADDR 0x5441000a
struct tag_custom {
int cmd;
};
℃。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。用内核部件完成。
答案 1 :(得分：4)
最新的Linux内核试图用设备树淘汰 ATAGS 。但是，setup.h文件定义了不同的 ATAG 值和结构。要解析这些，您需要添加类似的内容，
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);
在atags_parse.c中找到。当然，您需要将这些添加到 setup.h 中的值。
u-boot 的定义可能较少，因为它通过内核命令行传递参数，因为它不是 ARM 特定的。 命令参数或设备树可能是首选方法。如果您举例说明了您需要什么类型的配置，那么有人可能会提供更好的指导。
答案 2 :(得分：4)
按照此程序
为实现这一目标，需要修改2个部分。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.