我想在U-Boot和Linux内核中添加自定义的atag变量。
我该如何实现？
有没有添加ATAG变量到U-Boot和Linux的步骤？
如何在U-Boot和Linux内核中添加自定义的ATAG变量？
10
- Prashant Chikhalkar
1
2你可能应该考虑使用设备树。ATAGs已经被弃用了。 - tangrs
3个回答
5
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.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.
- MNW
5
最新的Linux内核试图用设备树来淘汰ATAGS。然而，在setup.h文件中，定义了不同的ATAG值和结构体。要解析这些内容，您需要像以下代码一样添加它们。
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);
这些内容可以在 atags_parse.c 中找到。当然，在 setup.h 中也需要添加它们的值。
u-boot 可能没有那么明确定义，因为它大多数情况下通过内核命令行传递参数，这不是 ARM 特有的。使用 命令参数 或 设备树 可能是首选方法。如果你提供了需要的配置类型示例，其他人可能会给予更好的指导。
- artless noise
1
4
按照以下步骤进行操作:
要实现这个目标，需要修改两个部分。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.
- vishnumotghare
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