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authorVivek Goyal <vgoyal@in.ibm.com>2005-06-25 14:58:15 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-25 16:24:52 -0700
commitb089f4a68eccd9782c89262c0d7cae146d5a8a40 (patch)
treea84874a801e54dd89e5093392aedf49cece4cb11 /Documentation/kdump/gdbmacros.txt
parenta3ea8ac8468f5c7fc65684331dfba3260d5b2d93 (diff)
downloadop-kernel-dev-b089f4a68eccd9782c89262c0d7cae146d5a8a40.zip
op-kernel-dev-b089f4a68eccd9782c89262c0d7cae146d5a8a40.tar.gz
[PATCH] kdump: Documentation for Kdump
This patch contains the documentation for the kexec based crash dump tool. Quick kdump-howto ================================================================ 1) Download and build kexec-tools. 2) Download and build the latest kexec/kdump (-mm) kernel patchset. Two kernels need to be built in order to get this feature working. A) First kernel: a) Enable "kexec system call" feature: CONFIG_KEXEC=y b) Physical load address (use default): CONFIG_PHYSICAL_START=0x100000 c) Enable "sysfs file system support": CONFIG_SYSFS=y d) Boot into first kernel with the command line parameter "crashkernel=Y@X": For example: "crashkernel=64M@16M". B) Second kernel: a) Enable "kernel crash dumps" feature: CONFIG_CRASH_DUMP=y b) Physical load addreess, use same load address as X in "crashkernel" kernel parameter in d) above, e.g., 16 MB or 0x1000000. CONFIG_PHYSICAL_START=0x1000000 c) Enable "/proc/vmcore support" (Optional, in Pseudo filesystems). CONFIG_PROC_VMCORE=y 3) Boot into the first kernel. 4) Load the second kernel to be booted using: kexec -p <second-kernel> --crash-dump --args-linux --append="root=<root-dev> maxcpus=1 init 1" 5) System reboots into the second kernel when a panic occurs. A module can be written to force the panic, for testing purposes. 6) See Documentation/kdump.txt for how to read the first kernel's memory image and how to analyze it. Signed-off-by: Hariprasad Nellitheertha <hari@in.ibm.com> Signed-off-by: Eric Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: randy_dunlap <rdunlap@xenotime.net> Signed-off-by: Maneesh Soni <maneesh@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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diff --git a/Documentation/kdump/gdbmacros.txt b/Documentation/kdump/gdbmacros.txt
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+#
+# This file contains a few gdb macros (user defined commands) to extract
+# useful information from kernel crashdump (kdump) like stack traces of
+# all the processes or a particular process and trapinfo.
+#
+# These macros can be used by copying this file in .gdbinit (put in home
+# directory or current directory) or by invoking gdb command with
+# --command=<command-file-name> option
+#
+# Credits:
+# Alexander Nyberg <alexn@telia.com>
+# V Srivatsa <vatsa@in.ibm.com>
+# Maneesh Soni <maneesh@in.ibm.com>
+#
+
+define bttnobp
+ set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
+ set $pid_off=((size_t)&((struct task_struct *)0)->pids[1].pid_list.next)
+ set $init_t=&init_task
+ set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
+ while ($next_t != $init_t)
+ set $next_t=(struct task_struct *)$next_t
+ printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm
+ printf "===================\n"
+ set var $stackp = $next_t.thread.esp
+ set var $stack_top = ($stackp & ~4095) + 4096
+
+ while ($stackp < $stack_top)
+ if (*($stackp) > _stext && *($stackp) < _sinittext)
+ info symbol *($stackp)
+ end
+ set $stackp += 4
+ end
+ set $next_th=(((char *)$next_t->pids[1].pid_list.next) - $pid_off)
+ while ($next_th != $next_t)
+ set $next_th=(struct task_struct *)$next_th
+ printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm
+ printf "===================\n"
+ set var $stackp = $next_t.thread.esp
+ set var $stack_top = ($stackp & ~4095) + 4096
+
+ while ($stackp < $stack_top)
+ if (*($stackp) > _stext && *($stackp) < _sinittext)
+ info symbol *($stackp)
+ end
+ set $stackp += 4
+ end
+ set $next_th=(((char *)$next_th->pids[1].pid_list.next) - $pid_off)
+ end
+ set $next_t=(char *)($next_t->tasks.next) - $tasks_off
+ end
+end
+document bttnobp
+ dump all thread stack traces on a kernel compiled with !CONFIG_FRAME_POINTER
+end
+
+define btt
+ set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
+ set $pid_off=((size_t)&((struct task_struct *)0)->pids[1].pid_list.next)
+ set $init_t=&init_task
+ set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
+ while ($next_t != $init_t)
+ set $next_t=(struct task_struct *)$next_t
+ printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm
+ printf "===================\n"
+ set var $stackp = $next_t.thread.esp
+ set var $stack_top = ($stackp & ~4095) + 4096
+ set var $stack_bot = ($stackp & ~4095)
+
+ set $stackp = *($stackp)
+ while (($stackp < $stack_top) && ($stackp > $stack_bot))
+ set var $addr = *($stackp + 4)
+ info symbol $addr
+ set $stackp = *($stackp)
+ end
+
+ set $next_th=(((char *)$next_t->pids[1].pid_list.next) - $pid_off)
+ while ($next_th != $next_t)
+ set $next_th=(struct task_struct *)$next_th
+ printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm
+ printf "===================\n"
+ set var $stackp = $next_t.thread.esp
+ set var $stack_top = ($stackp & ~4095) + 4096
+ set var $stack_bot = ($stackp & ~4095)
+
+ set $stackp = *($stackp)
+ while (($stackp < $stack_top) && ($stackp > $stack_bot))
+ set var $addr = *($stackp + 4)
+ info symbol $addr
+ set $stackp = *($stackp)
+ end
+ set $next_th=(((char *)$next_th->pids[1].pid_list.next) - $pid_off)
+ end
+ set $next_t=(char *)($next_t->tasks.next) - $tasks_off
+ end
+end
+document btt
+ dump all thread stack traces on a kernel compiled with CONFIG_FRAME_POINTER
+end
+
+define btpid
+ set var $pid = $arg0
+ set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
+ set $pid_off=((size_t)&((struct task_struct *)0)->pids[1].pid_list.next)
+ set $init_t=&init_task
+ set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
+ set var $pid_task = 0
+
+ while ($next_t != $init_t)
+ set $next_t=(struct task_struct *)$next_t
+
+ if ($next_t.pid == $pid)
+ set $pid_task = $next_t
+ end
+
+ set $next_th=(((char *)$next_t->pids[1].pid_list.next) - $pid_off)
+ while ($next_th != $next_t)
+ set $next_th=(struct task_struct *)$next_th
+ if ($next_th.pid == $pid)
+ set $pid_task = $next_th
+ end
+ set $next_th=(((char *)$next_th->pids[1].pid_list.next) - $pid_off)
+ end
+ set $next_t=(char *)($next_t->tasks.next) - $tasks_off
+ end
+
+ printf "\npid %d; comm %s:\n", $pid_task.pid, $pid_task.comm
+ printf "===================\n"
+ set var $stackp = $pid_task.thread.esp
+ set var $stack_top = ($stackp & ~4095) + 4096
+ set var $stack_bot = ($stackp & ~4095)
+
+ set $stackp = *($stackp)
+ while (($stackp < $stack_top) && ($stackp > $stack_bot))
+ set var $addr = *($stackp + 4)
+ info symbol $addr
+ set $stackp = *($stackp)
+ end
+end
+document btpid
+ backtrace of pid
+end
+
+
+define trapinfo
+ set var $pid = $arg0
+ set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
+ set $pid_off=((size_t)&((struct task_struct *)0)->pids[1].pid_list.next)
+ set $init_t=&init_task
+ set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
+ set var $pid_task = 0
+
+ while ($next_t != $init_t)
+ set $next_t=(struct task_struct *)$next_t
+
+ if ($next_t.pid == $pid)
+ set $pid_task = $next_t
+ end
+
+ set $next_th=(((char *)$next_t->pids[1].pid_list.next) - $pid_off)
+ while ($next_th != $next_t)
+ set $next_th=(struct task_struct *)$next_th
+ if ($next_th.pid == $pid)
+ set $pid_task = $next_th
+ end
+ set $next_th=(((char *)$next_th->pids[1].pid_list.next) - $pid_off)
+ end
+ set $next_t=(char *)($next_t->tasks.next) - $tasks_off
+ end
+
+ printf "Trapno %ld, cr2 0x%lx, error_code %ld\n", $pid_task.thread.trap_no, \
+ $pid_task.thread.cr2, $pid_task.thread.error_code
+
+end
+document trapinfo
+ Run info threads and lookup pid of thread #1
+ 'trapinfo <pid>' will tell you by which trap & possibly
+ addresthe kernel paniced.
+end
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