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<h3 class="section"><code>.symver</code></h3>



   <p>Use the <code>.symver</code> directive to bind symbols to specific version nodes

within a source file.  This is only supported on ELF platforms, and is

typically used when assembling files to be linked into a shared library. 

There are cases where it may make sense to use this in objects to be bound

into an application itself so as to override a versioned symbol from a

shared library.



   <p>For ELF targets, the <code>.symver</code> directive can be used like this:

<pre class="smallexample">     .symver <var>name</var>, <var>name2@nodename</var>

     </pre>

   If the symbol <var>name</var> is defined within the file

being assembled, the <code>.symver</code> directive effectively creates a symbol

alias with the name <var>name2@nodename</var>, and in fact the main reason that we

just don't try and create a regular alias is that the <var>@</var> character isn't

permitted in symbol names.  The <var>name2</var> part of the name is the actual name

of the symbol by which it will be externally referenced.  The name <var>name</var>

itself is merely a name of convenience that is used so that it is possible to

have definitions for multiple versions of a function within a single source

file, and so that the compiler can unambiguously know which version of a

function is being mentioned.  The <var>nodename</var> portion of the alias should be

the name of a node specified in the version script supplied to the linker when

building a shared library.  If you are attempting to override a versioned

symbol from a shared library, then <var>nodename</var> should correspond to the

nodename of the symbol you are trying to override.



   <p>If the symbol <var>name</var> is not defined within the file being assembled, all

references to <var>name</var> will be changed to <var>name2@nodename</var>.  If no

reference to <var>name</var> is made, <var>name2@nodename</var> will be removed from the

symbol table.



   <p>Another usage of the <code>.symver</code> directive is:

<pre class="smallexample">     .symver <var>name</var>, <var>name2@@nodename</var>

     </pre>

   In this case, the symbol <var>name</var> must exist and be defined within

the file being assembled. It is similar to <var>name2@nodename</var>. The

difference is <var>name2@@nodename</var> will also be used to resolve

references to <var>name2</var> by the linker.



   <p>The third usage of the <code>.symver</code> directive is:

<pre class="smallexample">     .symver <var>name</var>, <var>name2@@@nodename</var>

     </pre>

   When <var>name</var> is not defined within the

file being assembled, it is treated as <var>name2@nodename</var>. When

<var>name</var> is defined within the file being assembled, the symbol

name, <var>name</var>, will be changed to <var>name2@@nodename</var>.



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