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-rw-r--r--en_US.ISO8859-1/books/developers-handbook/kerneldebug/chapter.sgml81
-rw-r--r--en_US.ISO8859-1/books/handbook/kerneldebug/chapter.sgml81
2 files changed, 118 insertions, 44 deletions
diff --git a/en_US.ISO8859-1/books/developers-handbook/kerneldebug/chapter.sgml b/en_US.ISO8859-1/books/developers-handbook/kerneldebug/chapter.sgml
index 4cf1b19f75..70efe283f2 100644
--- a/en_US.ISO8859-1/books/developers-handbook/kerneldebug/chapter.sgml
+++ b/en_US.ISO8859-1/books/developers-handbook/kerneldebug/chapter.sgml
@@ -1,7 +1,7 @@
<!--
The FreeBSD Documentation Project
- $FreeBSD: doc/en_US.ISO_8859-1/books/handbook/kerneldebug/chapter.sgml,v 1.25 2000/07/14 21:57:34 ben Exp $
+ $FreeBSD: doc/en_US.ISO_8859-1/books/handbook/kerneldebug/chapter.sgml,v 1.26 2000/11/07 09:08:11 jkoshy Exp $
-->
<chapter id="kerneldebug">
@@ -554,33 +554,70 @@ Debugger (msg=0xf01b0383 "Boot flags requested debugger")
full access to the source, running it in gud-mode inside an Emacs window
(which gives you an automatic source code display in another Emacs
window) etc.</para>
+ </sect1>
+
+ <sect1>
+ <title>Debugging Loadable Modules Using GDB</title>
- <para>Remote GDB can also be used to debug LKMs. First build the LKM with
- debugging symbols:</para>
+ <para>When debugging a panic that occurred within a module, or
+ using remote GDB against a machine that uses dynamic modules,
+ you need to tell GDB how to obtain symbol information for those
+ modules.</para>
- <screen>&prompt.root; <userinput>cd /usr/src/lkm/linux</userinput>
+ <para>First, you need to build the module(s) with debugging
+ information:</para>
+
+ <screen>&prompt.root; <userinput>cd /sys/modules/linux</userinput>
&prompt.root; <userinput>make clean; make COPTS=-g</userinput></screen>
- <para>Then install this version of the module on the target machine, load
- it and use <command>modstat</command> to find out where it was
- loaded:</para>
-
- <screen>&prompt.root; <userinput>linux</userinput>
-&prompt.root; <userinput>modstat</userinput>
-Type Id Off Loadaddr Size Info Rev Module Name
-EXEC 0 4 f5109000 001c f510f010 1 linux_mod</screen>
-
- <para>Take the load address of the module and add 0x20 (probably to
- account for the a.out header). This is the address that the module code
- was relocated to. Use the <command>add-symbol-file</command> command in
- GDB to tell the debugger about the module:</para>
-
- <screen><prompt>(kgdb)</prompt> <userinput>add-symbol-file /usr/src/lkm/linux/linux_mod.o 0xf5109020</userinput>
-add symbol table from file "/usr/src/lkm/linux/linux_mod.o" at
-text_addr = 0xf5109020? (y or n) <userinput>y</userinput>
+ <para>If you are using remote GDB, you can run
+ <command>kldstat</command> on the target machine to find out
+ where the module was loaded:</para>
+
+ <screen>&prompt.root; <userinput>kldstat</userinput>
+Id Refs Address Size Name
+ 1 4 0xc0100000 1c1678 kernel
+ 2 1 0xc0a9e000 6000 linprocfs.ko
+ 3 1 0xc0ad7000 2000 warp_saver.ko
+ 4 1 0xc0adc000 11000 linux.ko
+</screen>
+
+ <para>If you are debugging a crash dump, you'll need to walk the
+ <literal>linker_files</literal> list, starting at
+ <literal>linker_files->tqh_first</literal> and following the
+ <literal>link.tqe_next</literal> pointers until you find the
+ entry with the <literal>filename</literal> you are looking for.
+ The <literal>address</literal> member of that entry is the load
+ address of the module.</para>
+
+ <para>Next, you need to find out the offset of the text section
+ within the module:</para>
+
+ <screen>&prompt.root; <userinput>objdump --section-headers /sys/modules/linux/linux.ko | grep text</userinput>
+ 3 .rel.text 000016e0 000038e0 000038e0 000038e0 2**2
+ 10 .text 00007f34 000062d0 000062d0 000062d0 2**2</screen>
+
+ <para>The one you want is the <literal>.text</literal> section,
+ section 10 in the above example. The fourth numerical field
+ (sixth field overall) is the offset in hex of the text section
+ within the file (0x62d0 in our example). Add this to the load
+ address reported by <command>kldstat</command> to obtain the
+ address of the module text in memory.</para>
+
+ <para>Take the load address of the module (as reported by
+ <command>kldstat</command>) and add the offset of the text
+ section within the module (0x62d0 + 0xc0adc000 = c0ae22d0 in our
+ example). This is the address that the module code was
+ relocated to. Use the <command>add-symbol-file</command>
+ command in GDB to tell the debugger about the module:</para>
+
+ <screen><prompt>(kgdb)</prompt> <userinput>add-symbol-file /sys/modules/linux/linux.ko 0xc0ae22d0</userinput>
+add symbol table from file "/sys/modules/linux/linux.ko" at text_addr = 0xc0ae22d0?
+(y or n) <userinput>y</userinput>
+Reading symbols from /sys/modules/linux/linux.ko...done.
<prompt>(kgdb)</prompt></screen>
- <para>You now have access to all the symbols in the LKM.</para>
+ <para>You now have access to all the symbols in the module.</para>
</sect1>
<sect1>
diff --git a/en_US.ISO8859-1/books/handbook/kerneldebug/chapter.sgml b/en_US.ISO8859-1/books/handbook/kerneldebug/chapter.sgml
index 4cf1b19f75..70efe283f2 100644
--- a/en_US.ISO8859-1/books/handbook/kerneldebug/chapter.sgml
+++ b/en_US.ISO8859-1/books/handbook/kerneldebug/chapter.sgml
@@ -1,7 +1,7 @@
<!--
The FreeBSD Documentation Project
- $FreeBSD: doc/en_US.ISO_8859-1/books/handbook/kerneldebug/chapter.sgml,v 1.25 2000/07/14 21:57:34 ben Exp $
+ $FreeBSD: doc/en_US.ISO_8859-1/books/handbook/kerneldebug/chapter.sgml,v 1.26 2000/11/07 09:08:11 jkoshy Exp $
-->
<chapter id="kerneldebug">
@@ -554,33 +554,70 @@ Debugger (msg=0xf01b0383 "Boot flags requested debugger")
full access to the source, running it in gud-mode inside an Emacs window
(which gives you an automatic source code display in another Emacs
window) etc.</para>
+ </sect1>
+
+ <sect1>
+ <title>Debugging Loadable Modules Using GDB</title>
- <para>Remote GDB can also be used to debug LKMs. First build the LKM with
- debugging symbols:</para>
+ <para>When debugging a panic that occurred within a module, or
+ using remote GDB against a machine that uses dynamic modules,
+ you need to tell GDB how to obtain symbol information for those
+ modules.</para>
- <screen>&prompt.root; <userinput>cd /usr/src/lkm/linux</userinput>
+ <para>First, you need to build the module(s) with debugging
+ information:</para>
+
+ <screen>&prompt.root; <userinput>cd /sys/modules/linux</userinput>
&prompt.root; <userinput>make clean; make COPTS=-g</userinput></screen>
- <para>Then install this version of the module on the target machine, load
- it and use <command>modstat</command> to find out where it was
- loaded:</para>
-
- <screen>&prompt.root; <userinput>linux</userinput>
-&prompt.root; <userinput>modstat</userinput>
-Type Id Off Loadaddr Size Info Rev Module Name
-EXEC 0 4 f5109000 001c f510f010 1 linux_mod</screen>
-
- <para>Take the load address of the module and add 0x20 (probably to
- account for the a.out header). This is the address that the module code
- was relocated to. Use the <command>add-symbol-file</command> command in
- GDB to tell the debugger about the module:</para>
-
- <screen><prompt>(kgdb)</prompt> <userinput>add-symbol-file /usr/src/lkm/linux/linux_mod.o 0xf5109020</userinput>
-add symbol table from file "/usr/src/lkm/linux/linux_mod.o" at
-text_addr = 0xf5109020? (y or n) <userinput>y</userinput>
+ <para>If you are using remote GDB, you can run
+ <command>kldstat</command> on the target machine to find out
+ where the module was loaded:</para>
+
+ <screen>&prompt.root; <userinput>kldstat</userinput>
+Id Refs Address Size Name
+ 1 4 0xc0100000 1c1678 kernel
+ 2 1 0xc0a9e000 6000 linprocfs.ko
+ 3 1 0xc0ad7000 2000 warp_saver.ko
+ 4 1 0xc0adc000 11000 linux.ko
+</screen>
+
+ <para>If you are debugging a crash dump, you'll need to walk the
+ <literal>linker_files</literal> list, starting at
+ <literal>linker_files->tqh_first</literal> and following the
+ <literal>link.tqe_next</literal> pointers until you find the
+ entry with the <literal>filename</literal> you are looking for.
+ The <literal>address</literal> member of that entry is the load
+ address of the module.</para>
+
+ <para>Next, you need to find out the offset of the text section
+ within the module:</para>
+
+ <screen>&prompt.root; <userinput>objdump --section-headers /sys/modules/linux/linux.ko | grep text</userinput>
+ 3 .rel.text 000016e0 000038e0 000038e0 000038e0 2**2
+ 10 .text 00007f34 000062d0 000062d0 000062d0 2**2</screen>
+
+ <para>The one you want is the <literal>.text</literal> section,
+ section 10 in the above example. The fourth numerical field
+ (sixth field overall) is the offset in hex of the text section
+ within the file (0x62d0 in our example). Add this to the load
+ address reported by <command>kldstat</command> to obtain the
+ address of the module text in memory.</para>
+
+ <para>Take the load address of the module (as reported by
+ <command>kldstat</command>) and add the offset of the text
+ section within the module (0x62d0 + 0xc0adc000 = c0ae22d0 in our
+ example). This is the address that the module code was
+ relocated to. Use the <command>add-symbol-file</command>
+ command in GDB to tell the debugger about the module:</para>
+
+ <screen><prompt>(kgdb)</prompt> <userinput>add-symbol-file /sys/modules/linux/linux.ko 0xc0ae22d0</userinput>
+add symbol table from file "/sys/modules/linux/linux.ko" at text_addr = 0xc0ae22d0?
+(y or n) <userinput>y</userinput>
+Reading symbols from /sys/modules/linux/linux.ko...done.
<prompt>(kgdb)</prompt></screen>
- <para>You now have access to all the symbols in the LKM.</para>
+ <para>You now have access to all the symbols in the module.</para>
</sect1>
<sect1>