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| <h3 class="section">D.15 Library List Format</h3> |
| |
| <p><a name="index-library-list-format_002c-remote-protocol-2531"></a> |
| On some platforms, a dynamic loader (e.g. <samp><span class="file">ld.so</span></samp>) runs in the |
| same process as your application to manage libraries. In this case, |
| <span class="sc">gdb</span> can use the loader's symbol table and normal memory |
| operations to maintain a list of shared libraries. On other |
| platforms, the operating system manages loaded libraries. |
| <span class="sc">gdb</span> can not retrieve the list of currently loaded libraries |
| through memory operations, so it uses the ‘<samp><span class="samp">qXfer:libraries:read</span></samp>’ |
| packet (see <a href="qXfer-library-list-read.html#qXfer-library-list-read">qXfer library list read</a>) instead. The remote stub |
| queries the target's operating system and reports which libraries |
| are loaded. |
| |
| <p>The ‘<samp><span class="samp">qXfer:libraries:read</span></samp>’ packet returns an XML document which |
| lists loaded libraries and their offsets. Each library has an |
| associated name and one or more segment or section base addresses, |
| which report where the library was loaded in memory. |
| |
| <p>For the common case of libraries that are fully linked binaries, the |
| library should have a list of segments. If the target supports |
| dynamic linking of a relocatable object file, its library XML element |
| should instead include a list of allocated sections. The segment or |
| section bases are start addresses, not relocation offsets; they do not |
| depend on the library's link-time base addresses. |
| |
| <p><span class="sc">gdb</span> must be linked with the Expat library to support XML |
| library lists. See <a href="Expat.html#Expat">Expat</a>. |
| |
| <p>A simple memory map, with one loaded library relocated by a single |
| offset, looks like this: |
| |
| <pre class="smallexample"> <library-list> |
| <library name="/lib/libc.so.6"> |
| <segment address="0x10000000"/> |
| </library> |
| </library-list> |
| </pre> |
| <p>Another simple memory map, with one loaded library with three |
| allocated sections (.text, .data, .bss), looks like this: |
| |
| <pre class="smallexample"> <library-list> |
| <library name="sharedlib.o"> |
| <section address="0x10000000"/> |
| <section address="0x20000000"/> |
| <section address="0x30000000"/> |
| </library> |
| </library-list> |
| </pre> |
| <p>The format of a library list is described by this DTD: |
| |
| <pre class="smallexample"> <!-- library-list: Root element with versioning --> |
| <!ELEMENT library-list (library)*> |
| <!ATTLIST library-list version CDATA #FIXED "1.0"> |
| <!ELEMENT library (segment*, section*)> |
| <!ATTLIST library name CDATA #REQUIRED> |
| <!ELEMENT segment EMPTY> |
| <!ATTLIST segment address CDATA #REQUIRED> |
| <!ELEMENT section EMPTY> |
| <!ATTLIST section address CDATA #REQUIRED> |
| </pre> |
| <p>In addition, segments and section descriptors cannot be mixed within a |
| single library element, and you must supply at least one segment or |
| section for each library. |
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