GNU Info

(ld.info)Output Section Data

---

Next: Output Section Keywords Prev: Input Section Up: SECTIONS

---

Enter node , (file) or (file)node

Output section data
-------------------

   You can include explicit bytes of data in an output section by using
`BYTE', `SHORT', `LONG', `QUAD', or `SQUAD' as an output section
command.  Each keyword is followed by an expression in parentheses
providing the value to store (Note: Expressions).  The value of the
expression is stored at the current value of the location counter.

   The `BYTE', `SHORT', `LONG', and `QUAD' commands store one, two,
four, and eight bytes (respectively).  After storing the bytes, the
location counter is incremented by the number of bytes stored.

   For example, this will store the byte 1 followed by the four byte
value of the symbol `addr':
     BYTE(1)
     LONG(addr)

   When using a 64 bit host or target, `QUAD' and `SQUAD' are the same;
they both store an 8 byte, or 64 bit, value.  When both host and target
are 32 bits, an expression is computed as 32 bits.  In this case `QUAD'
stores a 32 bit value zero extended to 64 bits, and `SQUAD' stores a 32
bit value sign extended to 64 bits.

   If the object file format of the output file has an explicit
endianness, which is the normal case, the value will be stored in that
endianness.  When the object file format does not have an explicit
endianness, as is true of, for example, S-records, the value will be
stored in the endianness of the first input object file.

   Note - these commands only work inside a section description and not
between them, so the following will produce an error from the linker:
     SECTIONS { .text : { *(.text) } LONG(1) .data : { *(.data) } }
   whereas this will work:
     SECTIONS { .text : { *(.text) ; LONG(1) } .data : { *(.data) } }

   You may use the `FILL' command to set the fill pattern for the
current section.  It is followed by an expression in parentheses.  Any
otherwise unspecified regions of memory within the section (for example,
gaps left due to the required alignment of input sections) are filled
with the value of the expression, repeated as necessary.  A `FILL'
statement covers memory locations after the point at which it occurs in
the section definition; by including more than one `FILL' statement,
you can have different fill patterns in different parts of an output
section.

   This example shows how to fill unspecified regions of memory with the
value `0x90':
     FILL(0x90909090)

   The `FILL' command is similar to the `=FILLEXP' output section
attribute, but it only affects the part of the section following the
`FILL' command, rather than the entire section.  If both are used, the
`FILL' command takes precedence.  Note: Output Section Fill, for
details on the fill expression.