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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html><head> <title></title> <link rel="stylesheet" media="screen" type="text/css" href="./style.css" /> <link rel="stylesheet" media="screen" type="text/css" href="./design.css" /> <link rel="stylesheet" media="print" type="text/css" href="./print.css" /> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /></head><body><a href=start.html>start</a></br><div class="toc"><div class="tocheader toctoggle" id="toc__header">Table of Contents</div><div id="toc__inside"><ul class="toc"><li class="level1"><div class="li"><span class="li"><a href="#gdb_debug_snippets" class="toc">GDB Debug Snippets</a></span></div><ul class="toc"><li class="clear"><ul class="toc"><li class="level3"><div class="li"><span class="li"><a href="#dump_peripheral_registers" class="toc">Dump Peripheral Registers</a></span></div></li><li class="level3"><div class="li"><span class="li"><a href="#dump_kernel_log_buffer" class="toc">Dump Kernel Log Buffer</a></span></div></li></ul></li></ul></li></ul></div></div><h1><a name="gdb_debug_snippets" id="gdb_debug_snippets">GDB Debug Snippets</a></h1><div class="level1"><p> Debugging with gdb can be augmented greatly via the user of gdb scripts. The <a href="http://sources.redhat.com/gdb/current/onlinedocs/gdb_toc.html" class="urlextern" title="http://sources.redhat.com/gdb/current/onlinedocs/gdb_toc.html" rel="nofollow">GDB manual</a> covers all of this in depth, so this document will contain a bunch of useful snippets.</p><p>To load a script at runtime, you can name it <code>.gdbinit</code> and place it in the directory you execute gdb. Another way is to use the <code>-x</code> option and specify the script to load automatically.</p><p>Note that some of these may make sense only when running with <a href="kgdb.html" class="wikilink1" title="kgdb.html">kgdb</a>.</p></div><!-- SECTION [1-543] --><h3><a name="dump_peripheral_registers" id="dump_peripheral_registers">Dump Peripheral Registers</a></h3><div class="level3"><pre class="code">define info-uart # only show read-destructive registers if user requests them ... set $UART_DESTROY = ($argc > 1) set $UART_BASE = $arg0 set $UART_RBR = $UART_BASE + 0x0000 set $UART_DLL = $UART_BASE + 0x0000 set $UART_IER = $UART_BASE + 0x0004 set $UART_DLH = $UART_BASE + 0x0004 set $UART_IIR = $UART_BASE + 0x0008 set $UART_LCR = $UART_BASE + 0x000C set $UART_MCR = $UART_BASE + 0x0010 set $UART_LSR = $UART_BASE + 0x0014 set $UART_SCR = $UART_BASE + 0x001C set $UART_GCTL = $UART_BASE + 0x0024 set $UART_LCR_VAL = *(unsigned short*)$UART_LCR set $UART_LCR_DLAB_0 = 0xF7 set $UART_LCR_DLAB_1 = 0xFF printf "Showing UART Registers at 0x%X\n", $UART_BASE set *(unsigned short*)$UART_LCR = $UART_LCR_VAL & $UART_LCR_DLAB_0 printf " RBR: " x/1th $UART_RBR printf " IER: " x/1th $UART_IER set *(unsigned short*)$UART_LCR = $UART_LCR_VAL & $UART_LCR_DLAB_1 printf " DLL: " x/1th $UART_DLL printf " DLH: " x/1th $UART_DLH set *(unsigned short*)$UART_LCR = $UART_LCR_VAL if $UART_DESTROY printf " IIR: " x/1th $UART_IIR else printf " IIR: <skipped destructive read>" end printf " LCR: " x/1th $UART_LCR printf " MCR: " x/1th $UART_MCR if $UART_DESTROY printf " LSR: " x/1th $UART_LSR else printf " LSR: <skipped destructive read>" end printf " SCR: " x/1th $UART_SCR printf " GCTL: " x/1th $UART_GCTLenddefine info-uart0 set $UART0_BASE = 0xFFC00400 info-uart $UART0_BASE ($argc > 0)enddefine info-uart1 set $UART1_BASE = 0xFFC02000 info-uart $UART1_BASE ($argc > 0)end</pre></div><!-- SECTION [544-2305] --><h3><a name="dump_kernel_log_buffer" id="dump_kernel_log_buffer">Dump Kernel Log Buffer</a></h3><div class="level3"><p> The kernel stores all of its printk() output in a circular buffer, so displaying this buffer properly requires a bit more work than just writing it as a string from the start.</p><pre class="code">define dump-dmesg set $start = log_start set $end = log_end set $buf = log_buf set $mask = log_buf_len - 1 while ($start != $end) set $c = $buf[$start & $mask] set $start = $start + 1 printf "%c", $c end printf "\n"end</pre></div><!-- SECTION [2306-] --></body></html>⌨️ 快捷键说明
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