CentOS7でcrashコマンドを実行し、ライブカーネルの状態を見られるようになるまでの準備（メモ）。
パッケージのインストール
crashコマンド
yumで普通に入る。
# yum install crash
Loaded plugins: fastestmirror
base | 3.6 kB 00:00
epel/x86_64/metalink | 6.3 kB 00:00
epel | 4.4 kB 00:00
extras | 3.4 kB 00:00
updates | 3.4 kB 00:00
epel/x86_64/primary_db | 3.3 MB 00:00
(1/2): epel/x86_64/updateinfo | 35 kB 00:00
(2/2): epel/x86_64/pkgtags | 1.3 MB 00:00
Loading mirror speeds from cached hostfile
* base: mirrors.hust.edu.cn
* epel: mirrors.yun-idc.com
* extras: ftp.tsukuba.wide.ad.jp
* updates: mirrors.yun-idc.com
Resolving Dependencies
--> Running transaction check
---> Package crash.x86_64 0:7.0.2-7.el7_0.1 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
================================================================================
Package Arch Version Repository Size
================================================================================
Installing:
crash x86_64 7.0.2-7.el7_0.1 updates 2.5 M
Transaction Summary
================================================================================
Install 1 Package
Total download size: 2.5 M
Installed size: 7.0 M
Is this ok [y/d/N]: y
Downloading packages:
crash-7.0.2-7.el7_0.1.x86_64.rpm | 2.5 MB 00:00
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Installing : crash-7.0.2-7.el7_0.1.x86_64 1/1
Verifying : crash-7.0.2-7.el7_0.1.x86_64 1/1
Installed:
crash.x86_64 0:7.0.2-7.el7_0.1
Complete!
kernel-debuginfo
カーネルのシンボル情報とか、vmlinuxとかのパッケージ。
CentOSのdebuginfoレポジトリに入っている。
CentOS7では、レポジトリ定義は既に "/etc/yum.repos.d/CentOS-Base.repo" 内にあり、disableされているだけ。--enablerepoを渡して有効にしてあげる。
# yum install --enablerepo=base-debuginfo kernel-debuginfo-`uname -r`
Loaded plugins: fastestmirror
base-debuginfo | 2.5 kB 00:00
base-debuginfo/x86_64/primary_db | 465 kB 00:01
Loading mirror speeds from cached hostfile
* base: mirrors.hust.edu.cn
* epel: mirrors.yun-idc.com
* extras: ftp.tsukuba.wide.ad.jp
* updates: mirrors.yun-idc.com
======================== N/S matched: kernel-debuginfo =========================
kernel-debuginfo-common-x86_64.x86_64 : Kernel source files used by
: kernel-debuginfo packages
kernel-debuginfo.x86_64 : Debug information for package kernel
Name and summary matches only, use "search all" for everything.
[root@localhost yum.repos.d]# yum install --enablerepo=base-debuginfo kernel-deb
uginfo
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: mirrors.hust.edu.cn
* epel: mirrors.yun-idc.com
* extras: ftp.tsukuba.wide.ad.jp
* updates: mirrors.yun-idc.com
Resolving Dependencies
--> Running transaction check
---> Package kernel-debuginfo.x86_64 0:3.10.0-123.8.1.el7 will be installed
--> Processing Dependency: kernel-debuginfo-common-x86_64 = 3.10.0-123.8.1.el7 for package: kernel-debuginfo-3.10.0-123.8.1.el7.x86_64
--> Running transaction check
---> Package kernel-debuginfo-common-x86_64.x86_64 0:3.10.0-123.8.1.el7 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
================================================================================
Package Arch Version Repository Size
================================================================================
Installing:
kernel-debuginfo x86_64 3.10.0-123.8.1.el7 base-debuginfo 247 M
Installing for dependencies:
kernel-debuginfo-common-x86_64 x86_64 3.10.0-123.8.1.el7 base-debuginfo 39 M
Transaction Summary
================================================================================
Install 1 Package (+1 Dependent package)
Total download size: 286 M
Installed size: 1.3 G
Is this ok [y/d/N]: y
Downloading packages:
warning: /var/cache/yum/x86_64/7/base-debuginfo/packages/kernel-debuginfo-common-x86_64-3.10.0-123.8.1.el7.x86_64.rpm: Header V3 RSA/SHA256 Signature, key ID b6792c39: NOKEY
Public key for kernel-debuginfo-common-x86_64-3.10.0-123.8.1.el7.x86_64.rpm is not installed
(1/2): kernel-debuginfo-common-x86_64-3.10.0-123.8.1.el7.x | 39 MB 00:46
(2/2): kernel-debuginfo-3.10.0-123.8.1.el7.x86_64.rpm | 247 MB 04:55
--------------------------------------------------------------------------------
Total 989 kB/s | 286 MB 04:55
Retrieving key from file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-Debug-7
Importing GPG key 0xB6792C39:
Userid : "CentOS-7 Debug (CentOS-7 Debuginfo RPMS) <security@centos.org>"
Fingerprint: 759d 690f 6099 2d52 6a35 8cbd d0f2 5a3c b679 2c39
Package : centos-release-7-0.1406.el7.centos.2.5.x86_64 (@updates)
From : /etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-Debug-7
Is this ok [y/N]: y
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Installing : kernel-debuginfo-common-x86_64-3.10.0-123.8.1.el7.x86_64 1/2
Installing : kernel-debuginfo-3.10.0-123.8.1.el7.x86_64 2/2
Verifying : kernel-debuginfo-common-x86_64-3.10.0-123.8.1.el7.x86_64 1/2
Verifying : kernel-debuginfo-3.10.0-123.8.1.el7.x86_64 2/2
Installed:
kernel-debuginfo.x86_64 0:3.10.0-123.8.1.el7
Dependency Installed:
kernel-debuginfo-common-x86_64.x86_64 0:3.10.0-123.8.1.el7
Complete!
結構大きい。
Total download size: 286 M
Installed size: 1.3 G
起動してみる
実行中のカーネルバージョン（unamer -r）と、上でインストールした kernel-debuginfo のバージョンが一致していれば、引数不要。
# crash
crash 7.0.2-7.el7_0.1
Copyright (C) 2002-2013 Red Hat, Inc.
Copyright (C) 2004, 2005, 2006, 2010 IBM Corporation
Copyright (C) 1999-2006 Hewlett-Packard Co
Copyright (C) 2005, 2006, 2011, 2012 Fujitsu Limited
Copyright (C) 2006, 2007 VA Linux Systems Japan K.K.
Copyright (C) 2005, 2011 NEC Corporation
Copyright (C) 1999, 2002, 2007 Silicon Graphics, Inc.
Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc.
This program is free software, covered by the GNU General Public License,
and you are welcome to change it and/or distribute copies of it under
certain conditions. Enter "help copying" to see the conditions.
This program has absolutely no warranty. Enter "help warranty" for details.
GNU gdb (GDB) 7.6
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-unknown-linux-gnu"...
KERNEL: /usr/lib/debug/lib/modules/3.10.0-123.8.1.el7.x86_64/vmlinux
DUMPFILE: /dev/crash
CPUS: 1
DATE: Thu Oct 9 13:09:22 2014
UPTIME: 16:55:43
LOAD AVERAGE: 0.16, 0.05, 0.06
TASKS: 280
NODENAME: localhost.localdomain
RELEASE: 3.10.0-123.8.1.el7.x86_64
VERSION: #1 SMP Mon Sep 22 19:06:58 UTC 2014
MACHINE: x86_64 (3392 Mhz)
MEMORY: 1 GB
PID: 5644
COMMAND: "crash"
TASK: ffff88003af78b60 [THREAD_INFO: ffff88001382c000]
CPU: 0
STATE: TASK_RUNNING (ACTIVE)
crash> bt -t
PID: 5644 TASK: ffff88003af78b60 CPU: 0 COMMAND: "crash"
START: __schedule at ffffffff815e75dd
[ffff88001382df08] vfs_read at ffffffff811af54c
[ffff88001382df38] sys_read at ffffffff811b0078
[ffff88001382df80] system_call_fastpath at ffffffff815f2a59
RIP: 00007fc7087d3850 RSP: 00007fffd0b45f00 RFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffffff815f2a59 RCX: 00000000000001f8
RDX: 0000000000001000 RSI: 0000000000e84fc0 RDI: 0000000000000004
RBP: 0000000000000004 R8: 000000001382d000 R9: 0000000000000002
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000e84fc0
R13: 0000000000e84fc0 R14: 0000000000001000 R15: 0000000000001000
ORIG_RAX: 0000000000000000 CS: 0033 SS: 002b
crash> quit
参考リンク
crashコマンドの使い方など。