标签归档：QEMU

虚拟机 img 镜像密码修改

本文介绍使用 libguestfs-tools 修改镜像文件密码的方法。

步骤

# 环境
# CentOS Linux release 7.9.2009 (AltArch)
# 鲲鹏 ARM 服务器

第一步：检查并修改qemu访问虚拟机镜像的权限

修改 qemu 配置文件 /etc/libvirt/qemu.conf，将 user = "root" 和 group = "root" 注释取消，并重启 libvirtd 或重启宿主机。

$ vim /etc/libvirt/qemu.conf
- #user = "root"
- #group = "root"
+ user = "root"
+ group = "root"

systemctl restart libvirtd

第二步：安装工具

# 安装libguestfs-tools
$ yum install libguestfs-tools 
$ systemctl start libvirtd

第三步：修改密码

# 以下两组命令貌似均可，但是实测我的环境仅第二个命令可用

$ virt-customize -a CentOS-7-x86_64-GenericCloud.qcow2 --root-password password:xxx
$ virt-sysprep --root-password password:123456 -a *.qcow2

# 若以下错误
# cannot access storage file (as uid:107, gid:107)permission denied
# 说明您第一步没有做，给一下权限再尝试

# 示例
[root@compute-arm-01 stl]$ virt-sysprep --root-password password:123456 -a bionic-server-cloudimg-arm64.img 
[   0.0] Examining the guest ...
[   5.4] Performing "abrt-data" ...
[   5.4] Performing "backup-files" ...
[   5.8] Performing "bash-history" ...
[   5.9] Performing "blkid-tab" ...
[   5.9] Performing "crash-data" ...
[   6.0] Performing "cron-spool" ...
[   6.0] Performing "dhcp-client-state" ...
[   6.0] Performing "dhcp-server-state" ...
[   6.0] Performing "dovecot-data" ...
[   6.0] Performing "logfiles" ...
[   6.1] Performing "machine-id" ...
[   6.2] Performing "mail-spool" ...
[   6.2] Performing "net-hostname" ...
[   6.2] Performing "net-hwaddr" ...
[   6.3] Performing "pacct-log" ...
[   6.4] Performing "package-manager-cache" ...
[   6.5] Performing "pam-data" ...
[   6.5] Performing "passwd-backups" ...
[   6.5] Performing "puppet-data-log" ...
[   6.6] Performing "rh-subscription-manager" ...
[   6.6] Performing "rhn-systemid" ...
[   6.7] Performing "rpm-db" ...
[   6.8] Performing "samba-db-log" ...
[   6.8] Performing "script" ...
[   6.8] Performing "smolt-uuid" ...
[   6.9] Performing "ssh-hostkeys" ...
[   6.9] Performing "ssh-userdir" ...
[   6.9] Performing "sssd-db-log" ...
[   7.0] Performing "tmp-files" ...
[   7.0] Performing "udev-persistent-net" ...
[   7.1] Performing "utmp" ...
[   7.1] Performing "yum-uuid" ...
[   7.1] Performing "customize" ...
[   7.2] Setting a random seed
virt-sysprep: warning: random seed could not be set for this type of guest
[   7.3] Setting the machine ID in /etc/machine-id
[   7.3] Setting passwords
[   8.7] Performing "lvm-uuids" ...

参考文献

GDB 调试 QEMU 源码跟踪 QMP 协议执行

发表评论

接上文，通过跟踪 libvirt 的源码，找到 virsh domblkinfo 最终是使用 QMP 协议从 QEMU 获取到关键字为 query-block 的数据，其中带有 wr_highest_offset 字段，该字段被 libvirt 认定为磁盘利用率中 Allocation 值的来源。

今天就尝试在 QEMU 中找到获取 wr_highest_offset 字段的方法。

环境准备

QEMU 4.0
Centos
鲲鹏 ARM

首先需要编译 QEMU 加入函数表，重新编译 QEMU在其中加入该字段即可，编译方法可以参考源码目录：

./configure --enable-debug

跟踪前需要定位到 QEMU 中填充该字段的函数，首先在源码中全局搜索 wr_highest_offset ，最终确定 block/qapi.c 文件中的 bdrv_query_bds_stats 函数最有可能是填充该字段的位置，下面就来跟踪这个函数的走向吧。

跟踪记录

一个虚拟机在宿主机中表现为一个 QEMU 的进程，在这里仅保留一个虚拟机，查询该虚拟机状态时 libvirt 回使用 unix socket 的方式发往该进程监听的 unix socket 服务。因此跟踪该虚拟机所在进程即可。

# ps -aux | grep qemu
qemu     2185346  0.6  0.5 3562240 333440 ?      Sl   10:05   2:20 /usr/bin/qemu-system-aarch64 -name guest=instance-000001bb,...imestamp=on
root     2472547  0.0  0.0 110784  2496 pts/3    S+   16:03   0:00 grep --color=auto qemu

GDB 开始跟踪：

gdb qemu-system-aarch64 2185346

在之前找到的目标函数处打上断点：

(gdb) b bdrv_query_bds_stats

之后 c 继续执行，尝试查询一下磁盘状态。

$ virsh domblkinfo 25 vda --human

Breakpoint 1, bdrv_query_bds_stats (bs=0x3b549940, blk_level=true) at /root/stl/qemu-4.0.0/block/qapi.c:509
509         BlockStats *s = NULL;

会发现终端卡住了，此时 gdb 中断了进程，说明我们找对函数了，下面我们继续追踪吧。

发现这个函数是在 qmp_query_blockstats 中被调用多次，最终得出结果。

544     }
(gdb) n
qmp_query_blockstats (has_query_nodes=false, query_nodes=false, errp=0xffffe3963110) at /root/stl/qemu-4.0.0/block/qapi.c:609
609                 s->has_device = true;
(gdb) p s->stats->wr_highest_offset 
$3 = 3072

下面主要就是跟着源码来看了，本文主要是讲了如何使用 GDB 跟踪 QEMU 源码，若有疑问欢迎留言。

参考文献

GDB调试qemu源码纪录

QEMU 编译报错 undefined reference to g_app_info_launch_default_for_uri_finish 解决过程

发表评论

编译 QEMU 时报如下错误：

/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/libgtk-3.so: undefined reference to `g_app_info_launch_default_for_uri_finish'
/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/libgtk-3.so: undefined reference to `g_type_check_instance_is_fundamentally_a'
/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/libgtk-3.so: undefined reference to `g_app_info_launch_default_for_uri_async'
/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/libgtk-3.so: undefined reference to `g_strv_contains'
/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/libgtk-3.so: undefined reference to `g_list_model_get_type'
/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/libgtk-3.so: undefined reference to `g_drive_is_removable'
/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/libgtk-3.so: undefined reference to `g_application_get_resource_base_path'
/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/libgtk-3.so: undefined reference to `g_log_structured_standard'
/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/libgtk-3.so: undefined reference to `g_type_get_instance_count'
/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/libgtk-3.so: undefined reference to `g_list_model_get_n_items'
/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/libgtk-3.so: undefined reference to `g_file_enumerator_iterate'
/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/libgtk-3.so: undefined reference to `g_param_spec_get_name_quark'
/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/libgtk-3.so: undefined reference to `g_list_model_get_item'
collect2: error: ld returned 1 exit status
make[1]: *** [qemu-system-x86_64] Error 1
make: *** [subdir-x86_64-softmmu] Error 2

先看一下报错的动态链接库依赖了哪些库：

$ ldd /lib64/libgtk-3.so       
        linux-vdso.so.1 =>  (0x00007ffc89762000)
        libgdk-3.so.0 => /lib64/libgdk-3.so.0 (0x00007f19938ab000)
        libgmodule-2.0.so.0 => /lib64/libgmodule-2.0.so.0 (0x00007f19936a7000)
        libpangocairo-1.0.so.0 => /lib64/libpangocairo-1.0.so.0 (0x00007f1993499000)
        libX11.so.6 => /lib64/libX11.so.6 (0x00007f199315b000)
        libXi.so.6 => /lib64/libXi.so.6 (0x00007f1992f4b000)
        libXfixes.so.3 => /lib64/libXfixes.so.3 (0x00007f1992d45000)
        libcairo-gobject.so.2 => /lib64/libcairo-gobject.so.2 (0x00007f1992b3c000)
        libcairo.so.2 => /lib64/libcairo.so.2 (0x00007f1992805000)
        libgdk_pixbuf-2.0.so.0 => /lib64/libgdk_pixbuf-2.0.so.0 (0x00007f19925dd000)
        libatk-1.0.so.0 => /lib64/libatk-1.0.so.0 (0x00007f19923b7000)
        libatk-bridge-2.0.so.0 => /lib64/libatk-bridge-2.0.so.0 (0x00007f1992188000)
        libwayland-client.so.0 => /lib64/libwayland-client.so.0 (0x00007f1991f79000)
        libepoxy.so.0 => /lib64/libepoxy.so.0 (0x00007f1991c4d000)
        libpangoft2-1.0.so.0 => /lib64/libpangoft2-1.0.so.0 (0x00007f1991a37000)
        libpango-1.0.so.0 => /lib64/libpango-1.0.so.0 (0x00007f19917f1000)
        libfontconfig.so.1 => /lib64/libfontconfig.so.1 (0x00007f19915af000)
        libgio-2.0.so.0 => /lib64/libgio-2.0.so.0 (0x00007f199120f000)
        libgobject-2.0.so.0 => /lib64/libgobject-2.0.so.0 (0x00007f1990fbe000)
        libglib-2.0.so.0 => /lib64/libglib-2.0.so.0 (0x00007f1990ca8000)
        libm.so.6 => /lib64/libm.so.6 (0x00007f19909a6000)
        libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f199078a000)
        libc.so.6 => /lib64/libc.so.6 (0x00007f19903bc000)
        libXinerama.so.1 => /lib64/libXinerama.so.1 (0x00007f19901b9000)
        libXrandr.so.2 => /lib64/libXrandr.so.2 (0x00007f198ffae000)
        libXcursor.so.1 => /lib64/libXcursor.so.1 (0x00007f198fda3000)
        libXcomposite.so.1 => /lib64/libXcomposite.so.1 (0x00007f198fba0000)
        libXdamage.so.1 => /lib64/libXdamage.so.1 (0x00007f198f99d000)
        libxkbcommon.so.0 => /lib64/libxkbcommon.so.0 (0x00007f198f75d000)
        libwayland-cursor.so.0 => /lib64/libwayland-cursor.so.0 (0x00007f198f555000)
        libwayland-egl.so.1 => /lib64/libwayland-egl.so.1 (0x00007f198f353000)
        libXext.so.6 => /lib64/libXext.so.6 (0x00007f198f141000)
        librt.so.1 => /lib64/librt.so.1 (0x00007f198ef39000)
        libdl.so.2 => /lib64/libdl.so.2 (0x00007f198ed35000)
        libpcre.so.1 => /lib64/libpcre.so.1 (0x00007f198ead3000)
        libfreetype.so.6 => /lib64/libfreetype.so.6 (0x00007f198e814000)
        libxcb.so.1 => /lib64/libxcb.so.1 (0x00007f198e5ec000)
        libpixman-1.so.0 => /lib64/libpixman-1.so.0 (0x00007f198e343000)
        libEGL.so.1 => /lib64/libEGL.so.1 (0x00007f198e12f000)
        libpng15.so.15 => /lib64/libpng15.so.15 (0x00007f198df04000)
        libxcb-shm.so.0 => /lib64/libxcb-shm.so.0 (0x00007f198dd00000)
        libxcb-render.so.0 => /lib64/libxcb-render.so.0 (0x00007f198daf2000)
        libXrender.so.1 => /lib64/libXrender.so.1 (0x00007f198d8e7000)
        libz.so.1 => /lib64/libz.so.1 (0x00007f198d6d1000)
        libGL.so.1 => /lib64/libGL.so.1 (0x00007f198d445000)
        libatspi.so.0 => /lib64/libatspi.so.0 (0x00007f198d214000)
        libdbus-1.so.3 => /lib64/libdbus-1.so.3 (0x00007f198cfc4000)
        libffi.so.6 => /lib64/libffi.so.6 (0x00007f198cdbc000)
        libharfbuzz.so.0 => /lib64/libharfbuzz.so.0 (0x00007f198cb1f000)
        libthai.so.0 => /lib64/libthai.so.0 (0x00007f198c913000)
        libfribidi.so.0 => /lib64/libfribidi.so.0 (0x00007f198c6f7000)
        libexpat.so.1 => /lib64/libexpat.so.1 (0x00007f198c4cd000)
        libuuid.so.1 => /lib64/libuuid.so.1 (0x00007f198c2c8000)
        libselinux.so.1 => /lib64/libselinux.so.1 (0x00007f198c0a1000)
        libresolv.so.2 => /lib64/libresolv.so.2 (0x00007f198be87000)
        libmount.so.1 => /lib64/libmount.so.1 (0x00007f198bc44000)
        libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00007f198ba2e000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f199449d000)
        libbz2.so.1 => /lib64/libbz2.so.1 (0x00007f198b81e000)
        libXau.so.6 => /lib64/libXau.so.6 (0x00007f198b61a000)
        libGLdispatch.so.0 => /lib64/libGLdispatch.so.0 (0x00007f198b364000)
        libGLX.so.0 => /lib64/libGLX.so.0 (0x00007f198b132000)
        libsystemd.so.0 => /lib64/libsystemd.so.0 (0x00007f198af01000)
        libgraphite2.so.3 => /lib64/libgraphite2.so.3 (0x00007f198acd3000)
        libblkid.so.1 => /lib64/libblkid.so.1 (0x00007f198aa93000)
        libcap.so.2 => /lib64/libcap.so.2 (0x00007f198a88e000)
        liblzma.so.5 => /lib64/liblzma.so.5 (0x00007f198a668000)
        liblz4.so.1 => /lib64/liblz4.so.1 (0x00007f198a459000)
        libgcrypt.so.11 => /lib64/libgcrypt.so.11 (0x00007f198a1d8000)
        libgpg-error.so.0 => /lib64/libgpg-error.so.0 (0x00007f1989fd3000)
        libdw.so.1 => /lib64/libdw.so.1 (0x00007f1989d82000)
        libattr.so.1 => /lib64/libattr.so.1 (0x00007f1989b7d000)
        libelf.so.1 => /lib64/libelf.so.1 (0x00007f1989965000)

观察输出，所有依赖的动态链接库都有指向一个内存地址，说明所依赖的链接库都已经被加载入内存，排除了链接库不存在情况，下面就有可能是某个链接库有问题了，接下来做两件事：

使用 objdump -T <lib name and path> ｜grep <funcname> 命令检索报错函数属于哪一个链接库；
使用 find / -name <lib name> 命令查找是否有哪一个报错链接库在系统的动态链接库搜索目录中有多个；

经过一番检索，发现 [libgio-2.0.so](http://libgio-2.0.so) 在系统so检索目录有两个，分别是 /usr/local/lib/libgio-2.0.so 和 /lib64/libgio-2.0.so ，其中 /lib64 为系统默认链接库存放位置，而 /usr/local 为编译安装库的默认安装位置，移除/usr/local/lib/libgio-2.0.so 之后再次尝试编译发现报错减少了。

此时发现系统曾编译安装了 glib ，可能是那时引入了一些错误的 so 库，因此进入编译目录 make uninstall 移除此前安装的错误的库，再次尝试编译发现编译通过。

总结

本次编译错误排查了很久，最后在大佬的协助下终于解决，此类缺少依赖错误排查错误思路可以总结为 检查链接库是否存在 -> 检查是否存在重复链接库 -> 移除错误链接库 。

参考文献

linux查看动态库/程序依赖的库