class: center, middle, title # How does an embedded linux board boot? #### Ryan Gaus --- class: inverted, center, middle, title ## I don't know this stuff. -- ### But hopefully I can at least give you the gist. --- class: inverted, center, middle, title ## Tools --- class: inverted, center, middle, title ### dd if=/oldfile.txt of=/newfile.txt bs=1 --- # dd `dd if=/oldfile.txt of=/newfile.txt bs=1` <div style="float: left;"> <th>/oldfile.txt</th> <table class="memory-map"> <tr> <td><</td> <td>!</td> <td>D</td> <td>O</td> <td>C</td> <td>T</td> <td>Y</td> <td>P</td> </tr> <tr> <td>E</td> <td> </td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> </tr> <tr> <td><</td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> <td> </td> </tr> <tr> <td> </td> <td><</td> <td>h</td> <td>e</td> <td>a</td> <td>d</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>t</td> <td>i</td> <td>t</td> </tr> <tr> <td>l</td> <td>e</td> <td>></td> <td>T</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> </tr> <tr> <td><</td> <td>/</td> <td>t</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> <td>></td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>m</td> <td>e</td> </tr> <tr> <td>t</td> <td>a</td> <td> </td> <td>c</td> <td>h</td> <td>a</td> <td>r</td> <td>s</td> </tr> <tr> <td>e</td> <td>t</td> <td>=</td> <td>"</td> <td>u</td> <td>t</td> <td>f</td> <td>-</td> </tr> <tr> <td>8</td> <td>"</td> <td>></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><</td> <td>s</td> <td>t</td> <td>y</td> <td>l</td> <td>e</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td>@</td> <td>i</td> </tr> <tr> <td>m</td> <td>p</td> <td>o</td> <td>r</td> <td>t</td> <td> </td> <td>u</td> <td>r</td> </tr> </table> </div> <div style="float: right;"> <th>/newfile.txt</th> <table class="memory-map"> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> </table> </div> --- # dd `dd if=/oldfile.txt of=/newfile.txt bs=1` <div style="float: left;"> <th>/oldfile.txt</th> <table class="memory-map"> <tr> <td><</td> <td>!</td> <td>D</td> <td>O</td> <td>C</td> <td>T</td> <td>Y</td> <td>P</td> </tr> <tr> <td>E</td> <td> </td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> </tr> <tr> <td><</td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> <td> </td> </tr> <tr> <td> </td> <td><</td> <td>h</td> <td>e</td> <td>a</td> <td>d</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>t</td> <td>i</td> <td>t</td> </tr> <tr> <td>l</td> <td>e</td> <td>></td> <td>T</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> </tr> <tr> <td><</td> <td>/</td> <td>t</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> <td>></td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>m</td> <td>e</td> </tr> <tr> <td>t</td> <td>a</td> <td> </td> <td>c</td> <td>h</td> <td>a</td> <td>r</td> <td>s</td> </tr> <tr> <td>e</td> <td>t</td> <td>=</td> <td>"</td> <td>u</td> <td>t</td> <td>f</td> <td>-</td> </tr> <tr> <td>8</td> <td>"</td> <td>></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><</td> <td>s</td> <td>t</td> <td>y</td> <td>l</td> <td>e</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td>@</td> <td>i</td> </tr> <tr> <td>m</td> <td>p</td> <td>o</td> <td>r</td> <td>t</td> <td> </td> <td>u</td> <td>r</td> </tr> </table> </div> <div style="float: right;"> <th>/newfile.txt</th> <table class="memory-map"> <tr> <td h><</td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> </table> </div> --- # dd `dd if=/oldfile.txt of=/newfile.txt bs=1` <div style="float: left;"> <th>/oldfile.txt</th> <table class="memory-map"> <tr> <td><</td> <td>!</td> <td>D</td> <td>O</td> <td>C</td> <td>T</td> <td>Y</td> <td>P</td> </tr> <tr> <td>E</td> <td> </td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> </tr> <tr> <td><</td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> <td> </td> </tr> <tr> <td> </td> <td><</td> <td>h</td> <td>e</td> <td>a</td> <td>d</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>t</td> <td>i</td> <td>t</td> </tr> <tr> <td>l</td> <td>e</td> <td>></td> <td>T</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> </tr> <tr> <td><</td> <td>/</td> <td>t</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> <td>></td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>m</td> <td>e</td> </tr> <tr> <td>t</td> <td>a</td> <td> </td> <td>c</td> <td>h</td> <td>a</td> <td>r</td> <td>s</td> </tr> <tr> <td>e</td> <td>t</td> <td>=</td> <td>"</td> <td>u</td> <td>t</td> <td>f</td> <td>-</td> </tr> <tr> <td>8</td> <td>"</td> <td>></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><</td> <td>s</td> <td>t</td> <td>y</td> <td>l</td> <td>e</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td>@</td> <td>i</td> </tr> <tr> <td>m</td> <td>p</td> <td>o</td> <td>r</td> <td>t</td> <td> </td> <td>u</td> <td>r</td> </tr> </table> </div> <div style="float: right;"> <th>/newfile.txt</th> <table class="memory-map"> <tr> <td><</td> <td h>D</td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> </table> </div> --- # dd `dd if=/oldfile.txt of=/newfile.txt bs=1` <div style="float: left;"> <th>/oldfile.txt</th> <table class="memory-map"> <tr> <td><</td> <td>!</td> <td>D</td> <td>O</td> <td>C</td> <td>T</td> <td>Y</td> <td>P</td> </tr> <tr> <td>E</td> <td> </td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> </tr> <tr> <td><</td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> <td> </td> </tr> <tr> <td> </td> <td><</td> <td>h</td> <td>e</td> <td>a</td> <td>d</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>t</td> <td>i</td> <td>t</td> </tr> <tr> <td>l</td> <td>e</td> <td>></td> <td>T</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> </tr> <tr> <td><</td> <td>/</td> <td>t</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> <td>></td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>m</td> <td>e</td> </tr> <tr> <td>t</td> <td>a</td> <td> </td> <td>c</td> <td>h</td> <td>a</td> <td>r</td> <td>s</td> </tr> <tr> <td>e</td> <td>t</td> <td>=</td> <td>"</td> <td>u</td> <td>t</td> <td>f</td> <td>-</td> </tr> <tr> <td>8</td> <td>"</td> <td>></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><</td> <td>s</td> <td>t</td> <td>y</td> <td>l</td> <td>e</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td>@</td> <td>i</td> </tr> <tr> <td>m</td> <td>p</td> <td>o</td> <td>r</td> <td>t</td> <td> </td> <td>u</td> <td>r</td> </tr> </table> </div> <div style="float: right;"> <th>/newfile.txt</th> <table class="memory-map"> <tr> <td><</td> <td>D</td> <td h>O</td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> </table> </div> --- # dd `dd if=/oldfile.txt of=/newfile.txt bs=1` <div style="float: left;"> <th>/oldfile.txt</th> <table class="memory-map"> <tr> <td><</td> <td>!</td> <td>D</td> <td>O</td> <td>C</td> <td>T</td> <td>Y</td> <td>P</td> </tr> <tr> <td>E</td> <td> </td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> </tr> <tr> <td><</td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> <td> </td> </tr> <tr> <td> </td> <td><</td> <td>h</td> <td>e</td> <td>a</td> <td>d</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>t</td> <td>i</td> <td>t</td> </tr> <tr> <td>l</td> <td>e</td> <td>></td> <td>T</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> </tr> <tr> <td><</td> <td>/</td> <td>t</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> <td>></td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>m</td> <td>e</td> </tr> <tr> <td>t</td> <td>a</td> <td> </td> <td>c</td> <td>h</td> <td>a</td> <td>r</td> <td>s</td> </tr> <tr> <td>e</td> <td>t</td> <td>=</td> <td>"</td> <td>u</td> <td>t</td> <td>f</td> <td>-</td> </tr> <tr> <td>8</td> <td>"</td> <td>></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><</td> <td>s</td> <td>t</td> <td>y</td> <td>l</td> <td>e</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td>@</td> <td>i</td> </tr> <tr> <td>m</td> <td>p</td> <td>o</td> <td>r</td> <td>t</td> <td> </td> <td>u</td> <td>r</td> </tr> </table> </div> <div style="float: right;"> <th>/newfile.txt</th> <table class="memory-map"> <tr> <td><</td> <td>!</td> <td>D</td> <td>O</td> <td>C</td> <td>T</td> <td>Y</td> <td>P</td> </tr> <tr> <td>E</td> <td> </td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> </tr> <tr> <td><</td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> <td> </td> </tr> <tr> <td> </td> <td><</td> <td>h</td> <td>e</td> <td>a</td> <td>d</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>t</td> <td>i</td> <td>t</td> </tr> <tr> <td>l</td> <td>e</td> <td>></td> <td>T</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> </tr> <tr> <td><</td> <td>/</td> <td>t</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> <td>></td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>m</td> <td>e</td> </tr> <tr> <td>t</td> <td>a</td> <td> </td> <td>c</td> <td>h</td> <td>a</td> <td>r</td> <td>s</td> </tr> <tr> <td>e</td> <td>t</td> <td>=</td> <td>"</td> <td>u</td> <td>t</td> <td>f</td> <td>-</td> </tr> <tr> <td>8</td> <td>"</td> <td>></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><</td> <td>s</td> <td>t</td> <td>y</td> <td>l</td> <td>e</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td>@</td> <td>i</td> </tr> <tr> <td>m</td> <td>p</td> <td>o</td> <td>r</td> <td>t</td> <td> </td> <td>u</td> <td>r</td> </tr> </table> </div> --- # dd `dd if=/oldfile.txt of=/newfile.txt bs=8` <div style="float: left;"> <th>/oldfile.txt</th> <table class="memory-map"> <tr> <td><</td> <td>!</td> <td>D</td> <td>O</td> <td>C</td> <td>T</td> <td>Y</td> <td>P</td> </tr> <tr> <td>E</td> <td> </td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> </tr> <tr> <td><</td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> <td> </td> </tr> <tr> <td> </td> <td><</td> <td>h</td> <td>e</td> <td>a</td> <td>d</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>t</td> <td>i</td> <td>t</td> </tr> <tr> <td>l</td> <td>e</td> <td>></td> <td>T</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> </tr> <tr> <td><</td> <td>/</td> <td>t</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> <td>></td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>m</td> <td>e</td> </tr> <tr> <td>t</td> <td>a</td> <td> </td> <td>c</td> <td>h</td> <td>a</td> <td>r</td> <td>s</td> </tr> <tr> <td>e</td> <td>t</td> <td>=</td> <td>"</td> <td>u</td> <td>t</td> <td>f</td> <td>-</td> </tr> <tr> <td>8</td> <td>"</td> <td>></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><</td> <td>s</td> <td>t</td> <td>y</td> <td>l</td> <td>e</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td>@</td> <td>i</td> </tr> <tr> <td>m</td> <td>p</td> <td>o</td> <td>r</td> <td>t</td> <td> </td> <td>u</td> <td>r</td> </tr> </table> </div> <div style="float: right;"> <th>/newfile.txt</th> <table class="memory-map"> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> </table> </div> --- # dd `dd if=/oldfile.txt of=/newfile.txt bs=8` <div style="float: left;"> <th>/oldfile.txt</th> <table class="memory-map"> <tr> <td><</td> <td>!</td> <td>D</td> <td>O</td> <td>C</td> <td>T</td> <td>Y</td> <td>P</td> </tr> <tr> <td>E</td> <td> </td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> </tr> <tr> <td><</td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> <td> </td> </tr> <tr> <td> </td> <td><</td> <td>h</td> <td>e</td> <td>a</td> <td>d</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>t</td> <td>i</td> <td>t</td> </tr> <tr> <td>l</td> <td>e</td> <td>></td> <td>T</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> </tr> <tr> <td><</td> <td>/</td> <td>t</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> <td>></td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>m</td> <td>e</td> </tr> <tr> <td>t</td> <td>a</td> <td> </td> <td>c</td> <td>h</td> <td>a</td> <td>r</td> <td>s</td> </tr> <tr> <td>e</td> <td>t</td> <td>=</td> <td>"</td> <td>u</td> <td>t</td> <td>f</td> <td>-</td> </tr> <tr> <td>8</td> <td>"</td> <td>></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><</td> <td>s</td> <td>t</td> <td>y</td> <td>l</td> <td>e</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td>@</td> <td>i</td> </tr> <tr> <td>m</td> <td>p</td> <td>o</td> <td>r</td> <td>t</td> <td> </td> <td>u</td> <td>r</td> </tr> </table> </div> <div style="float: right;"> <th>/newfile.txt</th> <table class="memory-map"> <tr> <td h><</td> <td h>!</td> <td h>D</td> <td h>O</td> <td h>C</td> <td h>T</td> <td h>Y</td> <td h>P</td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> </table> </div> --- # dd `dd if=/oldfile.txt of=/newfile.txt bs=8` <div style="float: left;"> <th>/oldfile.txt</th> <table class="memory-map"> <tr> <td><</td> <td>!</td> <td>D</td> <td>O</td> <td>C</td> <td>T</td> <td>Y</td> <td>P</td> </tr> <tr> <td>E</td> <td> </td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> </tr> <tr> <td><</td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> <td> </td> </tr> <tr> <td> </td> <td><</td> <td>h</td> <td>e</td> <td>a</td> <td>d</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>t</td> <td>i</td> <td>t</td> </tr> <tr> <td>l</td> <td>e</td> <td>></td> <td>T</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> </tr> <tr> <td><</td> <td>/</td> <td>t</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> <td>></td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>m</td> <td>e</td> </tr> <tr> <td>t</td> <td>a</td> <td> </td> <td>c</td> <td>h</td> <td>a</td> <td>r</td> <td>s</td> </tr> <tr> <td>e</td> <td>t</td> <td>=</td> <td>"</td> <td>u</td> <td>t</td> <td>f</td> <td>-</td> </tr> <tr> <td>8</td> <td>"</td> <td>></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><</td> <td>s</td> <td>t</td> <td>y</td> <td>l</td> <td>e</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td>@</td> <td>i</td> </tr> <tr> <td>m</td> <td>p</td> <td>o</td> <td>r</td> <td>t</td> <td> </td> <td>u</td> <td>r</td> </tr> </table> </div> <div style="float: right;"> <th>/newfile.txt</th> <table class="memory-map"> <tr> <td><</td> <td>!</td> <td>D</td> <td>O</td> <td>C</td> <td>T</td> <td>Y</td> <td>P</td> </tr> <tr> <td h>E</td> <td h> </td> <td h>h</td> <td h>t</td> <td h>m</td> <td h>l</td> <td h>></td> <td h> </td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> </table> </div> --- # dd `dd if=/oldfile.txt of=/newfile.txt bs=8` <div style="float: left;"> <th>/oldfile.txt</th> <table class="memory-map"> <tr> <td><</td> <td>!</td> <td>D</td> <td>O</td> <td>C</td> <td>T</td> <td>Y</td> <td>P</td> </tr> <tr> <td>E</td> <td> </td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> </tr> <tr> <td><</td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> <td> </td> </tr> <tr> <td> </td> <td><</td> <td>h</td> <td>e</td> <td>a</td> <td>d</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>t</td> <td>i</td> <td>t</td> </tr> <tr> <td>l</td> <td>e</td> <td>></td> <td>T</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> </tr> <tr> <td><</td> <td>/</td> <td>t</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> <td>></td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>m</td> <td>e</td> </tr> <tr> <td>t</td> <td>a</td> <td> </td> <td>c</td> <td>h</td> <td>a</td> <td>r</td> <td>s</td> </tr> <tr> <td>e</td> <td>t</td> <td>=</td> <td>"</td> <td>u</td> <td>t</td> <td>f</td> <td>-</td> </tr> <tr> <td>8</td> <td>"</td> <td>></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><</td> <td>s</td> <td>t</td> <td>y</td> <td>l</td> <td>e</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td>@</td> <td>i</td> </tr> <tr> <td>m</td> <td>p</td> <td>o</td> <td>r</td> <td>t</td> <td> </td> <td>u</td> <td>r</td> </tr> </table> </div> <div style="float: right;"> <th>/newfile.txt</th> <table class="memory-map"> <tr> <td><</td> <td>!</td> <td>D</td> <td>O</td> <td>C</td> <td>T</td> <td>Y</td> <td>P</td> </tr> <tr> <td>E</td> <td> </td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> </tr> <tr> <td><</td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> <td> </td> </tr> <tr> <td> </td> <td><</td> <td>h</td> <td>e</td> <td>a</td> <td>d</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>t</td> <td>i</td> <td>t</td> </tr> <tr> <td>l</td> <td>e</td> <td>></td> <td>T</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> </tr> <tr> <td><</td> <td>/</td> <td>t</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> <td>></td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>m</td> <td>e</td> </tr> <tr> <td>t</td> <td>a</td> <td> </td> <td>c</td> <td>h</td> <td>a</td> <td>r</td> <td>s</td> </tr> <tr> <td>e</td> <td>t</td> <td>=</td> <td>"</td> <td>u</td> <td>t</td> <td>f</td> <td>-</td> </tr> <tr> <td>8</td> <td>"</td> <td>></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><</td> <td>s</td> <td>t</td> <td>y</td> <td>l</td> <td>e</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td>@</td> <td>i</td> </tr> <tr> <td>m</td> <td>p</td> <td>o</td> <td>r</td> <td>t</td> <td> </td> <td>u</td> <td>r</td> </tr> </table> </div> --- # dd `dd if=/oldfile.txt of=/newfile.txt bs=8 count=2` <div style="float: left;"> <th>/oldfile.txt</th> <table class="memory-map"> <tr> <td><</td> <td>!</td> <td>D</td> <td>O</td> <td>C</td> <td>T</td> <td>Y</td> <td>P</td> </tr> <tr> <td>E</td> <td> </td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> </tr> <tr> <td><</td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> <td> </td> </tr> <tr> <td> </td> <td><</td> <td>h</td> <td>e</td> <td>a</td> <td>d</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>t</td> <td>i</td> <td>t</td> </tr> <tr> <td>l</td> <td>e</td> <td>></td> <td>T</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> </tr> <tr> <td><</td> <td>/</td> <td>t</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> <td>></td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>m</td> <td>e</td> </tr> <tr> <td>t</td> <td>a</td> <td> </td> <td>c</td> <td>h</td> <td>a</td> <td>r</td> <td>s</td> </tr> <tr> <td>e</td> <td>t</td> <td>=</td> <td>"</td> <td>u</td> <td>t</td> <td>f</td> <td>-</td> </tr> <tr> <td>8</td> <td>"</td> <td>></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><</td> <td>s</td> <td>t</td> <td>y</td> <td>l</td> <td>e</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td>@</td> <td>i</td> </tr> <tr> <td>m</td> <td>p</td> <td>o</td> <td>r</td> <td>t</td> <td> </td> <td>u</td> <td>r</td> </tr> </table> </div> <div style="float: right;"> <th>/newfile.txt</th> <table class="memory-map"> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> </table> </div> --- # dd `dd if=/oldfile.txt of=/newfile.txt bs=8 count=2` <div style="float: left;"> <th>/oldfile.txt</th> <table class="memory-map"> <tr> <td><</td> <td>!</td> <td>D</td> <td>O</td> <td>C</td> <td>T</td> <td>Y</td> <td>P</td> </tr> <tr> <td>E</td> <td> </td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> </tr> <tr> <td><</td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> <td> </td> </tr> <tr> <td> </td> <td><</td> <td>h</td> <td>e</td> <td>a</td> <td>d</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>t</td> <td>i</td> <td>t</td> </tr> <tr> <td>l</td> <td>e</td> <td>></td> <td>T</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> </tr> <tr> <td><</td> <td>/</td> <td>t</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> <td>></td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>m</td> <td>e</td> </tr> <tr> <td>t</td> <td>a</td> <td> </td> <td>c</td> <td>h</td> <td>a</td> <td>r</td> <td>s</td> </tr> <tr> <td>e</td> <td>t</td> <td>=</td> <td>"</td> <td>u</td> <td>t</td> <td>f</td> <td>-</td> </tr> <tr> <td>8</td> <td>"</td> <td>></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><</td> <td>s</td> <td>t</td> <td>y</td> <td>l</td> <td>e</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td>@</td> <td>i</td> </tr> <tr> <td>m</td> <td>p</td> <td>o</td> <td>r</td> <td>t</td> <td> </td> <td>u</td> <td>r</td> </tr> </table> </div> <div style="float: right;"> <th>/newfile.txt</th> <table class="memory-map"> <tr> <td h><</td> <td h>!</td> <td h>D</td> <td h>O</td> <td h>C</td> <td h>T</td> <td h>Y</td> <td h>P</td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> </table> </div> --- # dd `dd if=/oldfile.txt of=/newfile.txt bs=8 count=2` <div style="float: left;"> <th>/oldfile.txt</th> <table class="memory-map"> <tr> <td><</td> <td>!</td> <td>D</td> <td>O</td> <td>C</td> <td>T</td> <td>Y</td> <td>P</td> </tr> <tr> <td>E</td> <td> </td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> </tr> <tr> <td><</td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> <td> </td> </tr> <tr> <td> </td> <td><</td> <td>h</td> <td>e</td> <td>a</td> <td>d</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>t</td> <td>i</td> <td>t</td> </tr> <tr> <td>l</td> <td>e</td> <td>></td> <td>T</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> </tr> <tr> <td><</td> <td>/</td> <td>t</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> <td>></td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>m</td> <td>e</td> </tr> <tr> <td>t</td> <td>a</td> <td> </td> <td>c</td> <td>h</td> <td>a</td> <td>r</td> <td>s</td> </tr> <tr> <td>e</td> <td>t</td> <td>=</td> <td>"</td> <td>u</td> <td>t</td> <td>f</td> <td>-</td> </tr> <tr> <td>8</td> <td>"</td> <td>></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><</td> <td>s</td> <td>t</td> <td>y</td> <td>l</td> <td>e</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td>@</td> <td>i</td> </tr> <tr> <td>m</td> <td>p</td> <td>o</td> <td>r</td> <td>t</td> <td> </td> <td>u</td> <td>r</td> </tr> </table> </div> <div style="float: right;"> <th>/newfile.txt</th> <table class="memory-map"> <tr> <td><</td> <td>!</td> <td>D</td> <td>O</td> <td>C</td> <td>T</td> <td>Y</td> <td>P</td> </tr> <tr> <td>E</td> <td> </td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> </table> </div> --- # dd `dd if=/oldfile.txt of=/newfile.txt bs=8 skip=1 count=2` <div style="float: left;"> <th>/oldfile.txt</th> <table class="memory-map"> <tr> <td h><</td> <td h>!</td> <td h>D</td> <td h>O</td> <td h>C</td> <td h>T</td> <td h>Y</td> <td h>P</td> </tr> <tr> <td h>E</td> <td h> </td> <td h>h</td> <td h>t</td> <td h>m</td> <td h>l</td> <td h>></td> <td h> </td> </tr> <tr> <td><</td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> <td> </td> </tr> <tr> <td> </td> <td><</td> <td>h</td> <td>e</td> <td>a</td> <td>d</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>t</td> <td>i</td> <td>t</td> </tr> <tr> <td>l</td> <td>e</td> <td>></td> <td>T</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> </tr> <tr> <td><</td> <td>/</td> <td>t</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> <td>></td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>m</td> <td>e</td> </tr> <tr> <td>t</td> <td>a</td> <td> </td> <td>c</td> <td>h</td> <td>a</td> <td>r</td> <td>s</td> </tr> <tr> <td>e</td> <td>t</td> <td>=</td> <td>"</td> <td>u</td> <td>t</td> <td>f</td> <td>-</td> </tr> <tr> <td>8</td> <td>"</td> <td>></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><</td> <td>s</td> <td>t</td> <td>y</td> <td>l</td> <td>e</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td>@</td> <td>i</td> </tr> <tr> <td>m</td> <td>p</td> <td>o</td> <td>r</td> <td>t</td> <td> </td> <td>u</td> <td>r</td> </tr> </table> </div> <div style="float: right;"> <th>/newfile.txt</th> <table class="memory-map"> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td h><</td> <td h>!</td> <td h>D</td> <td h>O</td> <td h>C</td> <td h>T</td> <td h>Y</td> <td h>P</td> </tr> <tr> <td h>E</td> <td h> </td> <td h>h</td> <td h>t</td> <td h>m</td> <td h>l</td> <td h>></td> <td h> </td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> </table> </div> --- # dd `dd if=/oldfile.txt of=/newfile.txt bs=8 seek=3 count=2` <div style="float: left;"> <th>/oldfile.txt</th> <table class="memory-map"> <tr> <td><</td> <td>!</td> <td>D</td> <td>O</td> <td>C</td> <td>T</td> <td>Y</td> <td>P</td> </tr> <tr> <td>E</td> <td> </td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> </tr> <tr> <td><</td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> <td> </td> </tr> <tr> <td h> </td> <td h><</td> <td h>h</td> <td h>e</td> <td h>a</td> <td h>d</td> <td h>></td> <td h> </td> </tr> <tr> <td h> </td> <td h> </td> <td h> </td> <td h> </td> <td h><</td> <td h>t</td> <td h>i</td> <td h>t</td> </tr> <tr> <td>l</td> <td>e</td> <td>></td> <td>T</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> </tr> <tr> <td><</td> <td>/</td> <td>t</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> <td>></td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>m</td> <td>e</td> </tr> <tr> <td>t</td> <td>a</td> <td> </td> <td>c</td> <td>h</td> <td>a</td> <td>r</td> <td>s</td> </tr> <tr> <td>e</td> <td>t</td> <td>=</td> <td>"</td> <td>u</td> <td>t</td> <td>f</td> <td>-</td> </tr> <tr> <td>8</td> <td>"</td> <td>></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><</td> <td>s</td> <td>t</td> <td>y</td> <td>l</td> <td>e</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td>@</td> <td>i</td> </tr> <tr> <td>m</td> <td>p</td> <td>o</td> <td>r</td> <td>t</td> <td> </td> <td>u</td> <td>r</td> </tr> </table> </div> <div style="float: right;"> <th>/newfile.txt</th> <table class="memory-map"> <tr> <td h> </td> <td h><</td> <td h>h</td> <td h>e</td> <td h>a</td> <td h>d</td> <td h>></td> <td h> </td> </tr> <tr> <td h> </td> <td h> </td> <td h> </td> <td h> </td> <td h><</td> <td h>t</td> <td h>i</td> <td h>t</td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> </table> </div> --- # dd `dd if=/oldfile.txt of=/newfile.txt bs=8 seek=3 skip=5 count=2` <div style="float: left;"> <th>/oldfile.txt</th> <table class="memory-map"> <tr> <td><</td> <td>!</td> <td>D</td> <td>O</td> <td>C</td> <td>T</td> <td>Y</td> <td>P</td> </tr> <tr> <td>E</td> <td> </td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> </tr> <tr> <td><</td> <td>h</td> <td>t</td> <td>m</td> <td>l</td> <td>></td> <td> </td> <td> </td> </tr> <tr> <td h> </td> <td h><</td> <td h>h</td> <td h>e</td> <td h>a</td> <td h>d</td> <td h>></td> <td h> </td> </tr> <tr> <td h> </td> <td h> </td> <td h> </td> <td h> </td> <td h><</td> <td h>t</td> <td h>i</td> <td h>t</td> </tr> <tr> <td>l</td> <td>e</td> <td>></td> <td>T</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> </tr> <tr> <td><</td> <td>/</td> <td>t</td> <td>i</td> <td>t</td> <td>l</td> <td>e</td> <td>></td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td><</td> <td>m</td> <td>e</td> </tr> <tr> <td>t</td> <td>a</td> <td> </td> <td>c</td> <td>h</td> <td>a</td> <td>r</td> <td>s</td> </tr> <tr> <td>e</td> <td>t</td> <td>=</td> <td>"</td> <td>u</td> <td>t</td> <td>f</td> <td>-</td> </tr> <tr> <td>8</td> <td>"</td> <td>></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><</td> <td>s</td> <td>t</td> <td>y</td> <td>l</td> <td>e</td> <td>></td> <td> </td> </tr> <tr> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td>@</td> <td>i</td> </tr> <tr> <td>m</td> <td>p</td> <td>o</td> <td>r</td> <td>t</td> <td> </td> <td>u</td> <td>r</td> </tr> </table> </div> <div style="float: right;"> <th>/newfile.txt</th> <table class="memory-map"> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td h> </td> <td h><</td> <td h>h</td> <td h>e</td> <td h>a</td> <td h>d</td> <td h>></td> <td h> </td> </tr> <tr> <td h> </td> <td h> </td> <td h> </td> <td h> </td> <td h><</td> <td h>t</td> <td h>i</td> <td h>t</td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> </table> </div> --- class: inverted, center, middle, title ## hexdump -C oldfile.txt --- ``` $ hexdump -C oldfile.txt 00000000 3c 21 44 4f 43 54 59 50 45 20 68 74 6d 6c 3e 0a |<!DOCTYPE html>.| 00000010 3c 68 74 6d 6c 3e 0a 20 20 3c 68 65 61 64 3e 0a |<html>. <head>.| 00000020 20 20 20 20 3c 74 69 74 6c 65 3e 54 69 74 6c 65 | <title>Title| 00000030 3c 2f 74 69 74 6c 65 3e 0a 20 20 20 20 3c 6d 65 |</title>. <me| 00000040 74 61 20 63 68 61 72 73 65 74 3d 22 75 74 66 2d |ta charset="utf-| 00000050 38 22 3e 0a 20 20 20 20 3c 73 74 79 6c 65 3e 0a |8">. <style>.| 00000060 20 20 20 20 20 20 40 69 6d 70 6f 72 74 20 75 72 | @import ur| 00000070 6c 28 68 74 74 70 73 3a 2f 2f 66 6f 6e 74 73 2e |l(https://fonts.| 00000080 67 6f 6f 67 6c 65 61 70 69 73 2e 63 6f 6d 2f 63 |googleapis.com/c| 00000090 73 73 3f 66 61 6d 69 6c 79 3d 59 61 6e 6f 6e 65 |ss?family=Yanone| 000000a0 2b 4b 61 66 66 65 65 73 61 74 7a 29 3b 0a 20 20 |+Kaffeesatz);. | 000000b0 20 20 20 20 40 69 6d 70 6f 72 74 20 75 72 6c 28 | @import url(| 000000c0 68 74 74 70 73 3a 2f 2f 66 6f 6e 74 73 2e 67 6f |https://fonts.go| 000000d0 6f 67 6c 65 61 70 69 73 2e 63 6f 6d 2f 63 73 73 |ogleapis.com/css| 000000e0 3f 66 61 6d 69 6c 79 3d 44 72 6f 69 64 2b 53 65 |?family=Droid+Se| 000000f0 72 69 66 3a 34 30 30 2c 37 30 30 2c 34 30 30 69 |rif:400,700,400i| 00000100 74 61 6c 69 63 29 3b 0a 20 20 20 20 20 20 40 69 |talic);. @i| 00000110 6d 70 6f 72 74 20 75 72 6c 28 68 74 74 70 73 3a |mport url(https:| 00000120 2f 2f 66 6f 6e 74 73 2e 67 6f 6f 67 6c 65 61 70 |//fonts.googleap| 00000130 69 73 2e 63 6f 6d 2f 63 73 73 3f 66 61 6d 69 6c |is.com/css?famil| ``` <div style="position: absolute; top: 75px; left: 74px; width: 95px; height: 405px; background-color: red; z-index: 0; opacity: 0.2;"></div> <div style="position: absolute; top: 75px; left: 178px; width: 500px; height: 405px; background-color: green; z-index: 0; opacity: 0.2;"></div> <div style="position: absolute; top: 75px; left: 690px; width: 188px; height: 405px; background-color: royalblue; z-index: 0; opacity: 0.2;"></div> - <span style="color: red;">Location in memory, in hex</span> - <span style="color: green;">Values at each location, in hex (each row is split up into two, 8 byte chunks)</span> - <span style="color: blue;">Display the data values in an ascii representation (enabled with -C)</span> --- ## Display only part of a hexdump ``` $ hexdump -s 54 -n 21 -C oldfile.txt 00000036 65 3e 0a 20 20 20 20 3c 6d 65 74 61 20 63 68 61 |e>. <meta cha| 00000046 72 73 65 74 3d |rset=| 0000004b ``` <div style="position: absolute; top: 156px; left: 176px; width: 60px; height: 20px; background-color: red; z-index: 0; opacity: 0.2;"></div> <div style="position: absolute; top: 156px; left: 238px; width: 60px; height: 20px; background-color: green; z-index: 0; opacity: 0.2;"></div> - <span style="color: red;">-s optionally specifies a number of bytes to skip (works like an offset)</span> </span> - <span style="color: green;">-n optionally specified a number of bytes to display</span> --- class: inverted, center, middle, title ## Flash memory is a bunch of bits ### and what you do with those bits is up to you. (storing things raw? using a filesystem?) --- class: inverted, center, middle, title ### <span></span><</span>/prerequisites<span>></span> --- class: center, middle, title <a target="_blank" href="https://wiki.odroid.com/odroid-xu4/software/partition_table#ubuntu_partition_table">https://wiki.odroid.com/odroid-xu4/software/partition_table#ubuntu_partition_table</a> --- <table class="boot-memory" border="0"> <tr class="empty"><td style="color: rgba(0, 0, 0, 0.5)">Flash Memory</td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="one"><td>512b: fwbl1 (First stage bootloader)</td></tr> <tr class="empty"><td></td></tr> <tr class="two"><td>15872b: spl (U-boot SPL)</td></tr> <tr class="two"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="three"><td>32256b: uboot (bootloader)</td></tr> <tr class="three"><td></td></tr> <tr class="three"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="three" style="background-color: #a641ff;"><td>368128b: Trustzone</td></tr> </table> <p style="position: absolute; top: 70px; left: 640px;">Power On</p> <img style="position: absolute; top: 100px; left: 495px;" src="data:image/svg+xml;charset=utf-8;base64,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" /> -- <p style="position: absolute; top: 145px; left: 540px;">Last instruction of fwbl1: <br/>Jump to spl!</p> <img style="position: absolute; top: 150px; left: 495px;" src="data:image/svg+xml;charset=utf-8;base64,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" /> -- <p style="position: absolute; top: 265px; left: 540px;">Last instruction of spl: <br/>Jump to bootloader!</p> <img style="position: absolute; top: 270px; left: 495px;" src="data:image/svg+xml;charset=utf-8;base64,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" /> <img style="position: absolute; top: 550px; left: 495px;" src="data:image/svg+xml;charset=utf-8;base64,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" /> --- class: inverted, center, middle, title ## Demo - Fused SD Card --- ## NB - Running "bare metal" - Write to a random place in memory? You can! - Each board is different - Different offsets, some load images from filesystems instead (voodoo!) - At the whim of the cpu designer / manufacturer (and they have weird whims) --- <table class="boot-memory" border="0"> <tr class="empty"><td style="color: rgba(0, 0, 0, 0.5)">Flash Memory (continued)</td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="one"><td>1032kb: U-boot environment</td></tr> <tr class="one"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="two"><td>512M: rootfs A (disk partition)</td></tr> <tr class="two"><td></td></tr> <tr class="two"><td></td></tr> <tr class="two"><td></td></tr> <tr class="two"><td></td></tr> <tr class="two"><td></td></tr> <tr class="two"><td></td></tr> <tr class="two"><td></td></tr> <tr class="two"><td></td></tr> <tr class="three"><td>rootfs B (disk partition)</td></tr> <tr class="three"><td></td></tr> <tr class="three"><td></td></tr> </table> <p style="position: absolute; top: 20px; left: 540px;">U-boot: Interpret code in environment:</p> <ol style="position: absolute; top: 60px; left: 540px;"> <li>Look for three things in the rootfs: the kernel binary, the initramfs image, and the device tree</li> </ol> <img style="position: absolute; top: -70px; left: 495px;" src="data:image/svg+xml;charset=utf-8;base64,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" /> <table class="boot-memory" border="0" style="position: absolute; left: 550px; top: 300px; width: 300px;"> <tr class="empty"><td style="color: rgba(0, 0, 0, 0.5)">RAM</td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> </table> --- class: inverted, center, middle, title ## device tree? kernel binary? --- <table class="boot-memory" border="0"> <tr class="empty"><td style="color: rgba(0, 0, 0, 0.5)">Flash Memory (continued)</td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="one"><td>1032kb: U-boot environment</td></tr> <tr class="one"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="two"><td>512M: rootfs A (disk partition)</td></tr> <tr class="two"><td></td></tr> <tr class="two"><td></td></tr> <tr class="two"><td></td></tr> <tr class="two"><td></td></tr> <tr class="two"><td></td></tr> <tr class="two"><td></td></tr> <tr class="two"><td></td></tr> <tr class="two"><td></td></tr> <tr class="three"><td>rootfs B (disk partition)</td></tr> <tr class="three"><td></td></tr> <tr class="three"><td></td></tr> </table> <p style="position: absolute; top: 20px; left: 540px;">U-boot: Interpret code in environment:</p> <ol style="position: absolute; top: 60px; left: 540px;"> <li>Look for three things in the rootfs: the kernel binary, the initramfs image, and the device tree</li> <li>Load the kernel binary, device tree and initramfs into ram</li> </ol> <img style="position: absolute; top: -70px; left: 495px;" src="data:image/svg+xml;charset=utf-8;base64,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" /> <img style="position: absolute; top: 198px; left: 495px;" src="data:image/svg+xml;charset=utf-8;base64,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" /> <table class="boot-memory ram" border="0" style="position: absolute; left: 550px; top: 300px; width: 300px;"> <tr class="empty"><td style="color: rgba(0, 0, 0, 0.5)">RAM</td></tr> <tr class="empty"><td></td></tr> <tr class="two"><td>Kernel Binary (zImage)</td></tr> <tr class="two"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="one"><td>Initramfs</td></tr> <tr class="one"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="three"><td>Device Tree</td></tr> <tr class="three"><td></td></tr> <tr class="three"><td></td></tr> </table> -- <ol style="position: absolute; top: 60px; left: 540px;"> <li>Look for three things in the rootfs: the kernel binary, the initramfs image, and the device tree</li> <li>Load the kernel binary, device tree and initramfs into ram</li> <li>Set bootargs</li> </ol> -- <ol style="position: absolute; top: 60px; left: 540px;"> <li>Look for three things in the rootfs: the kernel binary, the initramfs image, and the device tree</li> <li>Load the kernel binary, device tree and initramfs into ram</li> <li>Set bootargs</li> <li>Boot the kernel, passing pointers<br/>to initramfs and device tree</li> </ol> <img style="position: absolute; top: 198px; left: 495px;" src="data:image/svg+xml;charset=utf-8;base64,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" /> --- class: inverted, center, middle, title ## Demo - Density OS --- <br/> <table class="boot-memory ram" border="0" style="position: absolute; left: 225px;"> <tr class="empty"><td style="color: rgba(0, 0, 0, 0.5)">RAM</td></tr> <tr class="empty"><td></td></tr> <tr class="two"><td>Kernel Binary (zImage)</td></tr> <tr class="two"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="one"><td>Initramfs</td></tr> <tr class="one"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="three"><td>Device Tree</td></tr> <tr class="three"><td></td></tr> <tr class="three"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> </table> --- <br/> <table class="boot-memory ram" border="0" style="position: absolute; left: 225px;"> <tr class="empty"><td style="color: rgba(0, 0, 0, 0.5)">RAM</td></tr> <tr class="empty"><td></td></tr> <tr class="three"><td>FIT Image</td></tr> <tr class="three"><td><small><small>Header: This FIT Image contains as the first item, an initramfs as the second item, and a device tree as the third item.</small></small></td></tr> <tr class="three"><td></td></tr> <tr class="three"><td><small>zImage</small></td></tr> <tr class="three"><td></td></tr> <tr class="three"><td><small>Initramfs</small></td></tr> <tr class="three"><td></td></tr> <tr class="three"><td><small>Device Tree</small></td></tr> <tr class="three"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> <tr class="empty"><td></td></tr> </table> --- class: inverted, center, middle, title ### Look at the source of Density OS (time permitting) --- class: inverted, center, middle, title ## Any questions? Thanks!