关于 ld 连接对齐函数 ALIGN() 和 NEXT()

robinswan

SECTIONS
{
        . = 0x00000000;

        . = ALIGN(4);
        .text      :
        {
          cpu/pxa/start.o        (.text)
          *(.text)
        }

        . = ALIGN(4);
        .rodata : { *(.rodata) }

        . = ALIGN(4);
        .data : { *(.data) }

        . = ALIGN(4);
        .got : { *(.got) }

        . = ALIGN(4);
        .bss : { *(.bss) }
}

上面是典型的 linker script 的片段，对于 ALIGN( ) 函数在这里的意义，
请哪位概念清晰的大侠详细说明一下！

kj501

估计应该是指定每个section按多少字节对齐

crquan

from `info ld`:

`ALIGN(EXP)'
     Return the location counter (`.') aligned to the next EXP boundary.
     `ALIGN' doesn't change the value of the location counter--it just
     does arithmetic on it.  Here is an example which aligns the output
     `.data' section to the next `0x2000' byte boundary after the
     preceding section and sets a variable within the section to the
     next `0x8000' boundary after the input sections:
          SECTIONS { ...
            .data ALIGN(0x2000): {
              *(.data)
              variable = ALIGN(0x8000);
            }
          ... }

     The first use of `ALIGN' in this example specifies the location of
     a section because it is used as the optional ADDRESS attribute of
     a section definition (*note Output Section Address:.  The second
     use of `ALIGN' is used to defines the value of a symbol.

     The builtin function `NEXT' is closely related to `ALIGN'.