linux的arch/arm/kernel/vmlinux.lds，真正内核一切从这里开始

这个vmlinux.lds由arch/arm/kernel/vmlinux.lds.S生成。

piggy.gz的入口定义在这里。

#include <asm-generic/vmlinux.lds.h>
#include <asm/thread_info.h>
#include <asm/memory.h>

OUTPUT_ARCH(arm)
ENTRY(stext)                            /*入口为stext*/

#ifndef __ARMEB__
jiffies = jiffies_64;
#else
jiffies = jiffies_64 + 4;
#endif

SECTIONS
{
#ifdef CONFIG_XIP_KERNEL
. = XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR);
#else
. = PAGE_OFFSET + TEXT_OFFSET;
#endif
.text.head : {                /*第一个段为.text.head，这个定义在arch/arm/kernel/head.S里面*/
_stext = .;
_sinittext = .;
*(.text.head)
}

.init : {               /* Init code and data          */
INIT_TEXT
_einittext = .;
__proc_info_begin = .;
*(.proc.info.init)
__proc_info_end = .;
__arch_info_begin = .;
*(.arch.info.init)
__arch_info_end = .;
__tagtable_begin = .;
*(.taglist.init)
__tagtable_end = .;
. = ALIGN(16);
__setup_start = .;
*(.init.setup)
__setup_end = .;
__early_begin = .;
*(.early_param.init)
__early_end = .;
__initcall_start = .;
INITCALLS
__initcall_end = .;
__con_initcall_start = .;
*(.con_initcall.init)
__con_initcall_end = .;
__security_initcall_start = .;
*(.security_initcall.init)
__security_initcall_end = .;
#ifdef CONFIG_BLK_DEV_INITRD
. = ALIGN(32);
__initramfs_start = .;
usr/built-in.o(.init.ramfs)
__initramfs_end = .;
#endif
. = ALIGN(4096);
__per_cpu_start = .;
*(.data.percpu)
*(.data.percpu.shared_aligned)
__per_cpu_end = .;
#ifndef CONFIG_XIP_KERNEL
__init_begin = _stext;
INIT_DATA
. = ALIGN(4096);
__init_end = .;
#endif
}

/DISCARD/ : {               /* Exit code and data          */
EXIT_TEXT
EXIT_DATA
*(.exitcall.exit)
#ifndef CONFIG_MMU
*(.fixup)
*(__ex_table)
#endif
}

.text : {               /* Real text segment          */
_text = .;          /* Text and read-only data     */
__exception_text_start = .;
*(.exception.text)
__exception_text_end = .;
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
KPROBES_TEXT
#ifdef CONFIG_MMU
*(.fixup)
#endif
*(.gnu.warning)
*(.rodata)
*(.rodata.*)
*(.glue_7)
*(.glue_7t)
*(.got)               /* Global offset table          */
}

RODATA

_etext = .;               /* End of text and rodata section */

#ifdef CONFIG_XIP_KERNEL
__data_loc = ALIGN(4);          /* location in binary */
. = PAGE_OFFSET + TEXT_OFFSET;
#else
. = ALIGN(THREAD_SIZE);
__data_loc = .;
#endif

.data : AT(__data_loc) {
__data_start = .;     /* address in memory */

/*
* first, the init task union, aligned
* to an 8192 byte boundary.
*/
*(.data.init_task)

#ifdef CONFIG_XIP_KERNEL
. = ALIGN(4096);
__init_begin = .;
INIT_DATA
. = ALIGN(4096);
__init_end = .;
#endif

. = ALIGN(4096);
__nosave_begin = .;
*(.data.nosave)
. = ALIGN(4096);
__nosave_end = .;

/*
* then the cacheline aligned data
*/
. = ALIGN(32);
*(.data.cacheline_aligned)

/*
* The exception fixup table (might need resorting at runtime)
*/
. = ALIGN(32);
__start___ex_table = .;
#ifdef CONFIG_MMU
*(__ex_table)
#endif
__stop___ex_table = .;

/*
* and the usual data section
*/
DATA_DATA
CONSTRUCTORS

_edata = .;
}
_edata_loc = __data_loc + SIZEOF(.data);

.bss : {
__bss_start = .;     /* BSS                    */
*(.bss)
*(COMMON)
_end = .;
}
/* Stabs debugging sections.     */
.stab 0 : { *(.stab) }
.stabstr 0 : { *(.stabstr) }
.stab.excl 0 : { *(.stab.excl) }
.stab.exclstr 0 : { *(.stab.exclstr) }
.stab.index 0 : { *(.stab.index) }
.stab.indexstr 0 : { *(.stab.indexstr) }
.comment 0 : { *(.comment) }
}