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 <body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
 <a name="Builtin-Functions"></a>
 <div class="header">
 <p>
 Previous: <a href="Expression-Section.html#Expression-Section" accesskey="p" rel="prev">Expression Section</a>, Up: <a href="Expressions.html#Expressions" accesskey="u" rel="up">Expressions</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="LD-Index.html#LD-Index" title="Index" rel="index">Index</a>]</p>
 </div>
 <hr>
 <a name="Builtin-Functions-1"></a>
 <h4 class="subsection">3.10.9 Builtin Functions</h4>
 <a name="index-functions-in-expressions"></a>
 <p>The linker script language includes a number of builtin functions for
 use in linker script expressions.
 </p>
 <dl compact="compact">
 <dt><code>ABSOLUTE(<var>exp</var>)</code></dt>
 <dd><a name="index-ABSOLUTE_0028exp_0029"></a>
 <a name="index-expression_002c-absolute"></a>
 <p>Return the absolute (non-relocatable, as opposed to non-negative) value
 of the expression <var>exp</var>.  Primarily useful to assign an absolute
 value to a symbol within a section definition, where symbol values are
 normally section relative.  See <a href="Expression-Section.html#Expression-Section">Expression Section</a>.
 </p>
 </dd>
 <dt><code>ADDR(<var>section</var>)</code></dt>
 <dd><a name="index-ADDR_0028section_0029"></a>
 <a name="index-section-address-in-expression"></a>
 <p>Return the address (VMA) of the named <var>section</var>.  Your
 script must previously have defined the location of that section.  In
 the following example, <code>start_of_output_1</code>, <code>symbol_1</code> and
 <code>symbol_2</code> are assigned equivalent values, except that
 <code>symbol_1</code> will be relative to the <code>.output1</code> section while
 the other two will be absolute:
 </p><div class="smallexample">
 <pre class="smallexample">SECTIONS { &hellip;
   .output1 :
     {
     start_of_output_1 = ABSOLUTE(.);
     &hellip;
     }
   .output :
     {
     symbol_1 = ADDR(.output1);
     symbol_2 = start_of_output_1;
     }
 &hellip; }
 </pre></div>

 </dd>
 <dt><code>ALIGN(<var>align</var>)</code></dt>
 <dt><code>ALIGN(<var>exp</var>,<var>align</var>)</code></dt>
 <dd><a name="index-ALIGN_0028align_0029"></a>
 <a name="index-ALIGN_0028exp_002calign_0029"></a>
 <a name="index-round-up-location-counter"></a>
 <a name="index-align-location-counter"></a>
 <a name="index-round-up-expression"></a>
 <a name="index-align-expression"></a>
 <p>Return the location counter (<code>.</code>) or arbitrary expression aligned
 to the next <var>align</var> boundary.  The single operand <code>ALIGN</code>
 doesn&rsquo;t change the value of the location counter&mdash;it just does
 arithmetic on it.  The two operand <code>ALIGN</code> allows an arbitrary
 expression to be aligned upwards (<code>ALIGN(<var>align</var>)</code> is
 equivalent to <code>ALIGN(., <var>align</var>)</code>).
 </p>
 <p>Here is an example which aligns the output <code>.data</code> section to the
 next <code>0x2000</code> byte boundary after the preceding section and sets a
 variable within the section to the next <code>0x8000</code> boundary after the
 input sections:
 </p><div class="smallexample">
 <pre class="smallexample">SECTIONS { &hellip;
   .data ALIGN(0x2000): {
     *(.data)
     variable = ALIGN(0x8000);
   }
 &hellip; }
 </pre></div>
 <p>The first use of <code>ALIGN</code> in this example specifies the location of
 a section because it is used as the optional <var>address</var> attribute of
 a section definition (see <a href="Output-Section-Address.html#Output-Section-Address">Output Section Address</a>).  The second use
 of <code>ALIGN</code> is used to defines the value of a symbol.
 </p>
 <p>The builtin function <code>NEXT</code> is closely related to <code>ALIGN</code>.
 </p>
 </dd>
 <dt><code>ALIGNOF(<var>section</var>)</code></dt>
 <dd><a name="index-ALIGNOF_0028section_0029"></a>
 <a name="index-section-alignment"></a>
 <p>Return the alignment in bytes of the named <var>section</var>, if that section has
 been allocated.  If the section has not been allocated when this is
 evaluated, the linker will report an error. In the following example,
 the alignment of the <code>.output</code> section is stored as the first
 value in that section.
 </p><div class="smallexample">
 <pre class="smallexample">SECTIONS{ &hellip;
   .output {
     LONG (ALIGNOF (.output))
     &hellip;
     }
 &hellip; }
 </pre></div>

 </dd>
 <dt><code>BLOCK(<var>exp</var>)</code></dt>
 <dd><a name="index-BLOCK_0028exp_0029"></a>
 <p>This is a synonym for <code>ALIGN</code>, for compatibility with older linker
 scripts.  It is most often seen when setting the address of an output
 section.
 </p>
 </dd>
 <dt><code>DATA_SEGMENT_ALIGN(<var>maxpagesize</var>, <var>commonpagesize</var>)</code></dt>
 <dd><a name="index-DATA_005fSEGMENT_005fALIGN_0028maxpagesize_002c-commonpagesize_0029"></a>
 <p>This is equivalent to either
 </p><div class="smallexample">
 <pre class="smallexample">(ALIGN(<var>maxpagesize</var>) + (. &amp; (<var>maxpagesize</var> - 1)))
 </pre></div>
 <p>or
 </p><div class="smallexample">
 <pre class="smallexample">(ALIGN(<var>maxpagesize</var>) + (. &amp; (<var>maxpagesize</var> - <var>commonpagesize</var>)))
 </pre></div>
 <p>depending on whether the latter uses fewer <var>commonpagesize</var> sized pages
 for the data segment (area between the result of this expression and
 <code>DATA_SEGMENT_END</code>) than the former or not.
 If the latter form is used, it means <var>commonpagesize</var> bytes of runtime
 memory will be saved at the expense of up to <var>commonpagesize</var> wasted
 bytes in the on-disk file.
 </p>
 <p>This expression can only be used directly in <code>SECTIONS</code> commands, not in
 any output section descriptions and only once in the linker script.
 <var>commonpagesize</var> should be less or equal to <var>maxpagesize</var> and should
 be the system page size the object wants to be optimized for (while still
 working on system page sizes up to <var>maxpagesize</var>).
 </p>
 <p>Example:
 </p><div class="smallexample">
 <pre class="smallexample">  . = DATA_SEGMENT_ALIGN(0x10000, 0x2000);
 </pre></div>

 </dd>
 <dt><code>DATA_SEGMENT_END(<var>exp</var>)</code></dt>
 <dd><a name="index-DATA_005fSEGMENT_005fEND_0028exp_0029"></a>
 <p>This defines the end of data segment for <code>DATA_SEGMENT_ALIGN</code>
 evaluation purposes.
 </p>
 <div class="smallexample">
 <pre class="smallexample">  . = DATA_SEGMENT_END(.);
 </pre></div>

 </dd>
 <dt><code>DATA_SEGMENT_RELRO_END(<var>offset</var>, <var>exp</var>)</code></dt>
 <dd><a name="index-DATA_005fSEGMENT_005fRELRO_005fEND_0028offset_002c-exp_0029"></a>
 <p>This defines the end of the <code>PT_GNU_RELRO</code> segment when
 &lsquo;<samp>-z relro</samp>&rsquo; option is used.  Second argument is returned.
 When &lsquo;<samp>-z relro</samp>&rsquo; option is not present, <code>DATA_SEGMENT_RELRO_END</code>
 does nothing, otherwise <code>DATA_SEGMENT_ALIGN</code> is padded so that
 <var>exp</var> + <var>offset</var> is aligned to the most commonly used page
 boundary for particular target.  If present in the linker script,
 it must always come in between <code>DATA_SEGMENT_ALIGN</code> and
 <code>DATA_SEGMENT_END</code>.
 </p>
 <div class="smallexample">
 <pre class="smallexample">  . = DATA_SEGMENT_RELRO_END(24, .);
 </pre></div>

 </dd>
 <dt><code>DEFINED(<var>symbol</var>)</code></dt>
 <dd><a name="index-DEFINED_0028symbol_0029"></a>
 <a name="index-symbol-defaults"></a>
 <p>Return 1 if <var>symbol</var> is in the linker global symbol table and is
 defined before the statement using DEFINED in the script, otherwise
 return 0.  You can use this function to provide
 default values for symbols.  For example, the following script fragment
 shows how to set a global symbol &lsquo;<samp>begin</samp>&rsquo; to the first location in
 the &lsquo;<samp>.text</samp>&rsquo; section&mdash;but if a symbol called &lsquo;<samp>begin</samp>&rsquo; already
 existed, its value is preserved:
 </p>
 <div class="smallexample">
 <pre class="smallexample">SECTIONS { &hellip;
   .text : {
     begin = DEFINED(begin) ? begin : . ;
     &hellip;
   }
   &hellip;
 }
 </pre></div>

 </dd>
 <dt><code>LENGTH(<var>memory</var>)</code></dt>
 <dd><a name="index-LENGTH_0028memory_0029"></a>
 <p>Return the length of the memory region named <var>memory</var>.
 </p>
 </dd>
 <dt><code>LOADADDR(<var>section</var>)</code></dt>
 <dd><a name="index-LOADADDR_0028section_0029"></a>
 <a name="index-section-load-address-in-expression"></a>
 <p>Return the absolute LMA of the named <var>section</var>.  (see <a href="Output-Section-LMA.html#Output-Section-LMA">Output Section LMA</a>).
 </p>
 </dd>
 <dt><code>LOG2CEIL(<var>exp</var>)</code></dt>
 <dd><a name="index-LOG2CEIL_0028exp_0029"></a>
 <p>Return the binary logarithm of <var>exp</var> rounded towards infinity.
 <code>LOG2CEIL(0)</code> returns 0.
 </p>
 <a name="index-MAX"></a>
 </dd>
 <dt><code>MAX(<var>exp1</var>, <var>exp2</var>)</code></dt>
 <dd><p>Returns the maximum of <var>exp1</var> and <var>exp2</var>.
 </p>
 <a name="index-MIN"></a>
 </dd>
 <dt><code>MIN(<var>exp1</var>, <var>exp2</var>)</code></dt>
 <dd><p>Returns the minimum of <var>exp1</var> and <var>exp2</var>.
 </p>
 </dd>
 <dt><code>NEXT(<var>exp</var>)</code></dt>
 <dd><a name="index-NEXT_0028exp_0029"></a>
 <a name="index-unallocated-address_002c-next"></a>
 <p>Return the next unallocated address that is a multiple of <var>exp</var>.
 This function is closely related to <code>ALIGN(<var>exp</var>)</code>; unless you
 use the <code>MEMORY</code> command to define discontinuous memory for the
 output file, the two functions are equivalent.
 </p>
 </dd>
 <dt><code>ORIGIN(<var>memory</var>)</code></dt>
 <dd><a name="index-ORIGIN_0028memory_0029"></a>
 <p>Return the origin of the memory region named <var>memory</var>.
 </p>
 </dd>
 <dt><code>SEGMENT_START(<var>segment</var>, <var>default</var>)</code></dt>
 <dd><a name="index-SEGMENT_005fSTART_0028segment_002c-default_0029"></a>
 <p>Return the base address of the named <var>segment</var>.  If an explicit
 value has already been given for this segment (with a command-line
 &lsquo;<samp>-T</samp>&rsquo; option) then that value will be returned otherwise the value
 will be <var>default</var>.  At present, the &lsquo;<samp>-T</samp>&rsquo; command-line option
 can only be used to set the base address for the &ldquo;text&rdquo;, &ldquo;data&rdquo;, and
 &ldquo;bss&rdquo; sections, but you can use <code>SEGMENT_START</code> with any segment
 name.
 </p>
 </dd>
 <dt><code>SIZEOF(<var>section</var>)</code></dt>
 <dd><a name="index-SIZEOF_0028section_0029"></a>
 <a name="index-section-size"></a>
 <p>Return the size in bytes of the named <var>section</var>, if that section has
 been allocated.  If the section has not been allocated when this is
 evaluated, the linker will report an error.  In the following example,
 <code>symbol_1</code> and <code>symbol_2</code> are assigned identical values:
 </p><div class="smallexample">
 <pre class="smallexample">SECTIONS{ &hellip;
   .output {
     .start = . ;
     &hellip;
     .end = . ;
     }
   symbol_1 = .end - .start ;
   symbol_2 = SIZEOF(.output);
 &hellip; }
 </pre></div>

 </dd>
 <dt><code>SIZEOF_HEADERS</code></dt>
 <dt><code>sizeof_headers</code></dt>
 <dd><a name="index-SIZEOF_005fHEADERS"></a>
 <a name="index-header-size"></a>
 <p>Return the size in bytes of the output file&rsquo;s headers.  This is
 information which appears at the start of the output file.  You can use
 this number when setting the start address of the first section, if you
 choose, to facilitate paging.
 </p>
 <a name="index-not-enough-room-for-program-headers"></a>
 <a name="index-program-headers_002c-not-enough-room"></a>
 <p>When producing an ELF output file, if the linker script uses the
 <code>SIZEOF_HEADERS</code> builtin function, the linker must compute the
 number of program headers before it has determined all the section
 addresses and sizes.  If the linker later discovers that it needs
 additional program headers, it will report an error &lsquo;<samp>not enough
 room for program headers</samp>&rsquo;.  To avoid this error, you must avoid using
 the <code>SIZEOF_HEADERS</code> function, or you must rework your linker
 script to avoid forcing the linker to use additional program headers, or
 you must define the program headers yourself using the <code>PHDRS</code>
 command (see <a href="PHDRS.html#PHDRS">PHDRS</a>).
 </p></dd>
 </dl>

 <hr>
 <div class="header">
 <p>
 Previous: <a href="Expression-Section.html#Expression-Section" accesskey="p" rel="prev">Expression Section</a>, Up: <a href="Expressions.html#Expressions" accesskey="u" rel="up">Expressions</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="LD-Index.html#LD-Index" title="Index" rel="index">Index</a>]</p>
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	<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
	<a name="Builtin-Functions"></a>
	<div class="header">
	<p>
	Previous: <a href="Expression-Section.html#Expression-Section" accesskey="p" rel="prev">Expression Section</a>, Up: <a href="Expressions.html#Expressions" accesskey="u" rel="up">Expressions</a>   [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="LD-Index.html#LD-Index" title="Index" rel="index">Index</a>]</p>
	</div>
	<hr>
	<a name="Builtin-Functions-1"></a>
	<h4 class="subsection">3.10.9 Builtin Functions</h4>
	<a name="index-functions-in-expressions"></a>
	<p>The linker script language includes a number of builtin functions for
	use in linker script expressions.
	</p>
	<dl compact="compact">
	<dt><code>ABSOLUTE(<var>exp</var>)</code></dt>
	<dd><a name="index-ABSOLUTE_0028exp_0029"></a>
	<a name="index-expression_002c-absolute"></a>
	<p>Return the absolute (non-relocatable, as opposed to non-negative) value
	of the expression <var>exp</var>. Primarily useful to assign an absolute
	value to a symbol within a section definition, where symbol values are
	normally section relative. See <a href="Expression-Section.html#Expression-Section">Expression Section</a>.
	</p>
	</dd>
	<dt><code>ADDR(<var>section</var>)</code></dt>
	<dd><a name="index-ADDR_0028section_0029"></a>
	<a name="index-section-address-in-expression"></a>
	<p>Return the address (VMA) of the named <var>section</var>. Your
	script must previously have defined the location of that section. In
	the following example, <code>start_of_output_1</code>, <code>symbol_1</code> and
	<code>symbol_2</code> are assigned equivalent values, except that
	<code>symbol_1</code> will be relative to the <code>.output1</code> section while
	the other two will be absolute:
	</p><div class="smallexample">
	<pre class="smallexample">SECTIONS { …
	.output1 :
	{
	start_of_output_1 = ABSOLUTE(.);
	…
	}
	.output :
	{
	symbol_1 = ADDR(.output1);
	symbol_2 = start_of_output_1;
	}
	… }
	</pre></div>

	</dd>
	<dt><code>ALIGN(<var>align</var>)</code></dt>
	<dt><code>ALIGN(<var>exp</var>,<var>align</var>)</code></dt>
	<dd><a name="index-ALIGN_0028align_0029"></a>
	<a name="index-ALIGN_0028exp_002calign_0029"></a>
	<a name="index-round-up-location-counter"></a>
	<a name="index-align-location-counter"></a>
	<a name="index-round-up-expression"></a>
	<a name="index-align-expression"></a>
	<p>Return the location counter (<code>.</code>) or arbitrary expression aligned
	to the next <var>align</var> boundary. The single operand <code>ALIGN</code>
	doesn’t change the value of the location counter—it just does
	arithmetic on it. The two operand <code>ALIGN</code> allows an arbitrary
	expression to be aligned upwards (<code>ALIGN(<var>align</var>)</code> is
	equivalent to <code>ALIGN(., <var>align</var>)</code>).
	</p>
	<p>Here is an example which aligns the output <code>.data</code> section to the
	next <code>0x2000</code> byte boundary after the preceding section and sets a
	variable within the section to the next <code>0x8000</code> boundary after the
	input sections:
	</p><div class="smallexample">
	<pre class="smallexample">SECTIONS { …
	.data ALIGN(0x2000): {
	*(.data)
	variable = ALIGN(0x8000);
	}
	… }
	</pre></div>
	<p>The first use of <code>ALIGN</code> in this example specifies the location of
	a section because it is used as the optional <var>address</var> attribute of
	a section definition (see <a href="Output-Section-Address.html#Output-Section-Address">Output Section Address</a>). The second use
	of <code>ALIGN</code> is used to defines the value of a symbol.
	</p>
	<p>The builtin function <code>NEXT</code> is closely related to <code>ALIGN</code>.
	</p>
	</dd>
	<dt><code>ALIGNOF(<var>section</var>)</code></dt>
	<dd><a name="index-ALIGNOF_0028section_0029"></a>
	<a name="index-section-alignment"></a>
	<p>Return the alignment in bytes of the named <var>section</var>, if that section has
	been allocated. If the section has not been allocated when this is
	evaluated, the linker will report an error. In the following example,
	the alignment of the <code>.output</code> section is stored as the first
	value in that section.
	</p><div class="smallexample">
	<pre class="smallexample">SECTIONS{ …
	.output {
	LONG (ALIGNOF (.output))
	…
	}
	… }
	</pre></div>

	</dd>
	<dt><code>BLOCK(<var>exp</var>)</code></dt>
	<dd><a name="index-BLOCK_0028exp_0029"></a>
	<p>This is a synonym for <code>ALIGN</code>, for compatibility with older linker
	scripts. It is most often seen when setting the address of an output
	section.
	</p>
	</dd>
	<dt><code>DATA_SEGMENT_ALIGN(<var>maxpagesize</var>, <var>commonpagesize</var>)</code></dt>
	<dd><a name="index-DATA_005fSEGMENT_005fALIGN_0028maxpagesize_002c-commonpagesize_0029"></a>
	<p>This is equivalent to either
	</p><div class="smallexample">
	<pre class="smallexample">(ALIGN(<var>maxpagesize</var>) + (. & (<var>maxpagesize</var> - 1)))
	</pre></div>
	<p>or
	</p><div class="smallexample">
	<pre class="smallexample">(ALIGN(<var>maxpagesize</var>) + (. & (<var>maxpagesize</var> - <var>commonpagesize</var>)))
	</pre></div>
	<p>depending on whether the latter uses fewer <var>commonpagesize</var> sized pages
	for the data segment (area between the result of this expression and
	<code>DATA_SEGMENT_END</code>) than the former or not.
	If the latter form is used, it means <var>commonpagesize</var> bytes of runtime
	memory will be saved at the expense of up to <var>commonpagesize</var> wasted
	bytes in the on-disk file.
	</p>
	<p>This expression can only be used directly in <code>SECTIONS</code> commands, not in
	any output section descriptions and only once in the linker script.
	<var>commonpagesize</var> should be less or equal to <var>maxpagesize</var> and should
	be the system page size the object wants to be optimized for (while still
	working on system page sizes up to <var>maxpagesize</var>).
	</p>
	<p>Example:
	</p><div class="smallexample">
	<pre class="smallexample"> . = DATA_SEGMENT_ALIGN(0x10000, 0x2000);
	</pre></div>

	</dd>
	<dt><code>DATA_SEGMENT_END(<var>exp</var>)</code></dt>
	<dd><a name="index-DATA_005fSEGMENT_005fEND_0028exp_0029"></a>
	<p>This defines the end of data segment for <code>DATA_SEGMENT_ALIGN</code>
	evaluation purposes.
	</p>
	<div class="smallexample">
	<pre class="smallexample"> . = DATA_SEGMENT_END(.);
	</pre></div>

	</dd>
	<dt><code>DATA_SEGMENT_RELRO_END(<var>offset</var>, <var>exp</var>)</code></dt>
	<dd><a name="index-DATA_005fSEGMENT_005fRELRO_005fEND_0028offset_002c-exp_0029"></a>
	<p>This defines the end of the <code>PT_GNU_RELRO</code> segment when
	‘<samp>-z relro</samp>’ option is used. Second argument is returned.
	When ‘<samp>-z relro</samp>’ option is not present, <code>DATA_SEGMENT_RELRO_END</code>
	does nothing, otherwise <code>DATA_SEGMENT_ALIGN</code> is padded so that
	<var>exp</var> + <var>offset</var> is aligned to the most commonly used page
	boundary for particular target. If present in the linker script,
	it must always come in between <code>DATA_SEGMENT_ALIGN</code> and
	<code>DATA_SEGMENT_END</code>.
	</p>
	<div class="smallexample">
	<pre class="smallexample"> . = DATA_SEGMENT_RELRO_END(24, .);
	</pre></div>

	</dd>
	<dt><code>DEFINED(<var>symbol</var>)</code></dt>
	<dd><a name="index-DEFINED_0028symbol_0029"></a>
	<a name="index-symbol-defaults"></a>
	<p>Return 1 if <var>symbol</var> is in the linker global symbol table and is
	defined before the statement using DEFINED in the script, otherwise
	return 0. You can use this function to provide
	default values for symbols. For example, the following script fragment
	shows how to set a global symbol ‘<samp>begin</samp>’ to the first location in
	the ‘<samp>.text</samp>’ section—but if a symbol called ‘<samp>begin</samp>’ already
	existed, its value is preserved:
	</p>
	<div class="smallexample">
	<pre class="smallexample">SECTIONS { …
	.text : {
	begin = DEFINED(begin) ? begin : . ;
	…
	}
	…
	}
	</pre></div>

	</dd>
	<dt><code>LENGTH(<var>memory</var>)</code></dt>
	<dd><a name="index-LENGTH_0028memory_0029"></a>
	<p>Return the length of the memory region named <var>memory</var>.
	</p>
	</dd>
	<dt><code>LOADADDR(<var>section</var>)</code></dt>
	<dd><a name="index-LOADADDR_0028section_0029"></a>
	<a name="index-section-load-address-in-expression"></a>
	<p>Return the absolute LMA of the named <var>section</var>. (see <a href="Output-Section-LMA.html#Output-Section-LMA">Output Section LMA</a>).
	</p>
	</dd>
	<dt><code>LOG2CEIL(<var>exp</var>)</code></dt>
	<dd><a name="index-LOG2CEIL_0028exp_0029"></a>
	<p>Return the binary logarithm of <var>exp</var> rounded towards infinity.
	<code>LOG2CEIL(0)</code> returns 0.
	</p>
	<a name="index-MAX"></a>
	</dd>
	<dt><code>MAX(<var>exp1</var>, <var>exp2</var>)</code></dt>
	<dd><p>Returns the maximum of <var>exp1</var> and <var>exp2</var>.
	</p>
	<a name="index-MIN"></a>
	</dd>
	<dt><code>MIN(<var>exp1</var>, <var>exp2</var>)</code></dt>
	<dd><p>Returns the minimum of <var>exp1</var> and <var>exp2</var>.
	</p>
	</dd>
	<dt><code>NEXT(<var>exp</var>)</code></dt>
	<dd><a name="index-NEXT_0028exp_0029"></a>
	<a name="index-unallocated-address_002c-next"></a>
	<p>Return the next unallocated address that is a multiple of <var>exp</var>.
	This function is closely related to <code>ALIGN(<var>exp</var>)</code>; unless you
	use the <code>MEMORY</code> command to define discontinuous memory for the
	output file, the two functions are equivalent.
	</p>
	</dd>
	<dt><code>ORIGIN(<var>memory</var>)</code></dt>
	<dd><a name="index-ORIGIN_0028memory_0029"></a>
	<p>Return the origin of the memory region named <var>memory</var>.
	</p>
	</dd>
	<dt><code>SEGMENT_START(<var>segment</var>, <var>default</var>)</code></dt>
	<dd><a name="index-SEGMENT_005fSTART_0028segment_002c-default_0029"></a>
	<p>Return the base address of the named <var>segment</var>. If an explicit
	value has already been given for this segment (with a command-line
	‘<samp>-T</samp>’ option) then that value will be returned otherwise the value
	will be <var>default</var>. At present, the ‘<samp>-T</samp>’ command-line option
	can only be used to set the base address for the “text”, “data”, and
	“bss” sections, but you can use <code>SEGMENT_START</code> with any segment
	name.
	</p>
	</dd>
	<dt><code>SIZEOF(<var>section</var>)</code></dt>
	<dd><a name="index-SIZEOF_0028section_0029"></a>
	<a name="index-section-size"></a>
	<p>Return the size in bytes of the named <var>section</var>, if that section has
	been allocated. If the section has not been allocated when this is
	evaluated, the linker will report an error. In the following example,
	<code>symbol_1</code> and <code>symbol_2</code> are assigned identical values:
	</p><div class="smallexample">
	<pre class="smallexample">SECTIONS{ …
	.output {
	.start = . ;
	…
	.end = . ;
	}
	symbol_1 = .end - .start ;
	symbol_2 = SIZEOF(.output);
	… }
	</pre></div>

	</dd>
	<dt><code>SIZEOF_HEADERS</code></dt>
	<dt><code>sizeof_headers</code></dt>
	<dd><a name="index-SIZEOF_005fHEADERS"></a>
	<a name="index-header-size"></a>
	<p>Return the size in bytes of the output file’s headers. This is
	information which appears at the start of the output file. You can use
	this number when setting the start address of the first section, if you
	choose, to facilitate paging.
	</p>
	<a name="index-not-enough-room-for-program-headers"></a>
	<a name="index-program-headers_002c-not-enough-room"></a>
	<p>When producing an ELF output file, if the linker script uses the
	<code>SIZEOF_HEADERS</code> builtin function, the linker must compute the
	number of program headers before it has determined all the section
	addresses and sizes. If the linker later discovers that it needs
	additional program headers, it will report an error ‘<samp>not enough
	room for program headers</samp>’. To avoid this error, you must avoid using
	the <code>SIZEOF_HEADERS</code> function, or you must rework your linker
	script to avoid forcing the linker to use additional program headers, or
	you must define the program headers yourself using the <code>PHDRS</code>
	command (see <a href="PHDRS.html#PHDRS">PHDRS</a>).
	</p></dd>
	</dl>

	<hr>
	<div class="header">
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