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| <h3 class="section">E.16 Memory Map Format</h3> |
| |
| <p><a name="index-memory-map-format-3633"></a> |
| To be able to write into flash memory, <span class="sc">gdb</span> needs to obtain a |
| memory map from the target. This section describes the format of the |
| memory map. |
| |
| <p>The memory map is obtained using the ‘<samp><span class="samp">qXfer:memory-map:read</span></samp>’ |
| (see <a href="qXfer-memory-map-read.html#qXfer-memory-map-read">qXfer memory map read</a>) packet and is an XML document that |
| lists memory regions. |
| |
| <p><span class="sc">gdb</span> must be linked with the Expat library to support XML |
| memory maps. See <a href="Expat.html#Expat">Expat</a>. |
| |
| <p>The top-level structure of the document is shown below: |
| |
| <pre class="smallexample"> <?xml version="1.0"?> |
| <!DOCTYPE memory-map |
| PUBLIC "+//IDN gnu.org//DTD GDB Memory Map V1.0//EN" |
| "http://sourceware.org/gdb/gdb-memory-map.dtd"> |
| <memory-map> |
| region... |
| </memory-map> |
| </pre> |
| <p>Each region can be either: |
| |
| <ul> |
| <li>A region of RAM starting at <var>addr</var> and extending for <var>length</var> |
| bytes from there: |
| |
| <pre class="smallexample"> <memory type="ram" start="<var>addr</var>" length="<var>length</var>"/> |
| </pre> |
| <li>A region of read-only memory: |
| |
| <pre class="smallexample"> <memory type="rom" start="<var>addr</var>" length="<var>length</var>"/> |
| </pre> |
| <li>A region of flash memory, with erasure blocks <var>blocksize</var> |
| bytes in length: |
| |
| <pre class="smallexample"> <memory type="flash" start="<var>addr</var>" length="<var>length</var>"> |
| <property name="blocksize"><var>blocksize</var></property> |
| </memory> |
| </pre> |
| </ul> |
| |
| <p>Regions must not overlap. <span class="sc">gdb</span> assumes that areas of memory not covered |
| by the memory map are RAM, and uses the ordinary ‘<samp><span class="samp">M</span></samp>’ and ‘<samp><span class="samp">X</span></samp>’ |
| packets to write to addresses in such ranges. |
| |
| <p>The formal DTD for memory map format is given below: |
| |
| <pre class="smallexample"> <!-- ................................................... --> |
| <!-- Memory Map XML DTD ................................ --> |
| <!-- File: memory-map.dtd .............................. --> |
| <!-- .................................... .............. --> |
| <!-- memory-map.dtd --> |
| <!-- memory-map: Root element with versioning --> |
| <!ELEMENT memory-map (memory)*> |
| <!ATTLIST memory-map version CDATA #FIXED "1.0.0"> |
| <!ELEMENT memory (property)*> |
| <!-- memory: Specifies a memory region, |
| and its type, or device. --> |
| <!ATTLIST memory type (ram|rom|flash) #REQUIRED |
| start CDATA #REQUIRED |
| length CDATA #REQUIRED> |
| <!-- property: Generic attribute tag --> |
| <!ELEMENT property (#PCDATA | property)*> |
| <!ATTLIST property name (blocksize) #REQUIRED> |
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