CentOS 7 ISO镜像定制内核版本

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在一些场景下需要在业务安装之前升级操作系统内核版本，既如此，直接定制内核版本，当操作系统灌装完成时自带高版本内核，效率会更高。

安装依赖

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yum install -y createrepo genisoimage syslinux isomd5sum ncurses-devel bc flex

挂载官方Minimal镜像

这里我们先采用Minimal镜像进行实验

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[root@localhost opt]# cd /opt
[root@localhost opt]# curl -O "https://mirrors.tuna.tsinghua.edu.cn/centos/7.9.2009/isos/x86_64/CentOS-7-x86_64-Minimal-2009.iso"
[root@localhost opt]# mkdir -p /mnt/cdrom

[root@localhost opt]# mount -o loop /opt/CentOS-7-x86_64-Minimal-2009.iso /mnt/cdrom
mount: /dev/loop0 is write-protected, mounting read-only

[root@localhost opt]# ls -lrt /mnt/cdrom/
total 696
-rw-rw-r-- 21 root root   1690 Dec 10  2015 RPM-GPG-KEY-CentOS-Testing-7
-rw-rw-r-- 21 root root   1690 Dec 10  2015 RPM-GPG-KEY-CentOS-7
-rw-rw-r-- 21 root root  18009 Dec 10  2015 GPL
-rw-rw-r-- 21 root root    227 Aug 30  2017 EULA
drwxr-xr-x  2 root root   2048 Oct 27  2020 LiveOS
drwxr-xr-x  3 root root   2048 Oct 27  2020 EFI
drwxr-xr-x  3 root root   2048 Oct 27  2020 images
-rw-r--r--  3 root root     14 Oct 30  2020 CentOS_BuildTag
drwxr-xr-x  2 root root   2048 Nov  3  2020 isolinux
drwxr-xr-x  2 root root 673792 Nov  4  2020 Packages
drwxr-xr-x  2 root root   4096 Nov  4  2020 repodata
-r--r--r--  1 root root   2883 Nov  4  2020 TRANS.TBL

拷贝镜像内容

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[root@localhost opt]# mkdir /ISO
[root@localhost opt]# cp -raf /mnt/cdrom/* /ISO
[root@localhost opt]# ls -lrt /ISO
total 328
-rw-rw-r-- 1 root root   1690 Dec 10  2015 RPM-GPG-KEY-CentOS-Testing-7
-rw-rw-r-- 1 root root   1690 Dec 10  2015 RPM-GPG-KEY-CentOS-7
-rw-rw-r-- 1 root root  18009 Dec 10  2015 GPL
-rw-rw-r-- 1 root root    227 Aug 30  2017 EULA
drwxr-xr-x 2 root root     43 Oct 27  2020 LiveOS
drwxr-xr-x 3 root root     35 Oct 27  2020 EFI
drwxr-xr-x 3 root root     57 Oct 27  2020 images
-rw-r--r-- 1 root root     14 Oct 30  2020 CentOS_BuildTag
drwxr-xr-x 2 root root    198 Nov  3  2020 isolinux
drwxr-xr-x 2 root root 225280 Nov  4  2020 Packages
drwxr-xr-x 2 root root   4096 Nov  4  2020 repodata
-r--r--r-- 1 root root   2883 Nov  4  2020 TRANS.TBL

替换5.15内核包

此前在在CentOS 7上编译和升级Linux内核一文中，介绍了如何编译和升级5.15内核，这里我们就复用。

先看下Minimal镜像中自带的内核相关包

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[root@localhost opt]# cd /ISO/Packages/
[root@localhost Packages]# ls -lrt kernel-*.rpm
-rw-rw-r-- 1 root root 52709940 Oct 20  2020 kernel-3.10.0-1160.el7.x86_64.rpm
-rw-rw-r-- 1 root root  8514900 Oct 20  2020 kernel-tools-3.10.0-1160.el7.x86_64.rpm
-rw-rw-r-- 1 root root  8405528 Oct 20  2020 kernel-tools-libs-3.10.0-1160.el7.x86_64.rpm

删除3.10内核包:

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rm -f kernel-3.10.0-1160.el7.x86_64.rpm

将5.15.145版本内核放入/ISO/Packages/内

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[root@localhost Packages]# ls -lrt kernel-*.rpm
-rw-rw-r-- 1 root root  8514900 Oct 20  2020 kernel-tools-3.10.0-1160.el7.x86_64.rpm
-rw-rw-r-- 1 root root  8405528 Oct 20  2020 kernel-tools-libs-3.10.0-1160.el7.x86_64.rpm
-rw-r--r-- 1 root root 59958256 Dec 23 20:33 kernel-ml-5.15.145-1.el7.x86_64.rpm

编辑引导文件

BIOS引导

编辑isolinux/isolinux.cfg文件，需要修改label linux部分，其中label部分menu default唯一，设置镜像默认进入模式

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label linux
  menu label ^Install CentOS 7.9 (Kernel-5.15.145-1)
  menu default
  kernel vmlinuz
  append initrd=initrd.img inst.stage2=hd:LABEL=CentOS7

label check
  menu label Test this ^media & install CentOS 7
  kernel vmlinuz
  append initrd=initrd.img inst.stage2=hd:LABEL=CentOS\x207\x20x86_64 rd.live.check quiet

menu separator # insert an empty line

EFI引导

编辑EFI/BOOT/grub.cfg文件，修改menuentry ‘Install CentOS 7’部分

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search --no-floppy --set=root -l 'CentOS 7 x86_64'

### BEGIN /etc/grub.d/10_linux ###
menuentry 'Install CentOS 7.9 (Kernel-5.15.145-1)' --class fedora --class gnu-linux --class gnu --class os {
        linuxefi /images/pxeboot/vmlinuz inst.stage2=hd:LABEL=CentOS7 quiet
        initrdefi /images/pxeboot/initrd.img
}

准备comps.xml

在生成安装盘之前，需要注意对comps.xml文件进行修改。这个文件用来告知安装程序anaconda，用户选择了某个组是应该有哪些包需要安装，定义了在安装过程中，包是如何被捆绑在一起的。

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[root@localhost ISO]# ls -lrt /mnt/cdrom/repodata/
total 3055
-rw-r--r-- 2 root root    811 Oct 27  2020 repomd.xml.asc
-rw-r--r-- 2 root root 744670 Oct 30  2020 cca56f3cffa18f1e52302dbfcf2f0250a94c8a37acd8347ed6317cb52c8369dc-c7-x86_64-comps.xml
-rw-r--r-- 2 root root 156763 Oct 30  2020 a4e2b46586aa556c3b6f814dad5b16db5a669984d66b68e873586cd7c7253301-c7-x86_64-comps.xml.gz
-rw-r--r-- 1 root root 232765 Nov  3  2020 95e7738c1060314a439e6970aeebe54ee6a729cc66351fc02edc057a524b0ea3-filelists.xml.gz
-rw-r--r-- 1 root root 312426 Nov  3  2020 91cceb5edd8689502596ad298ec64bad45991dd758a8180bfe18a6d8a3281c28-filelists.sqlite.bz2
-rw-r--r-- 1 root root 205995 Nov  3  2020 6da4a53c1231b84985efc60f9ccac32e6c33c0831d7f352d003fd4bfc39c373a-other.sqlite.bz2
-rw-r--r-- 1 root root 183471 Nov  3  2020 57ae40f3495cc6e04d91b0eb504e740f901c3b48ec2179e3736256db08fa755c-other.xml.gz
-rw-r--r-- 1 root root 409248 Nov  3  2020 136912ae46ca9ed27661ea6528fd544962d83095e3cdbc6149a37ddedf3a153c-primary.xml.gz
-rw-r--r-- 1 root root   3734 Nov  3  2020 repomd.xml
-rw-r--r-- 1 root root   3539 Nov  3  2020 d4de4d1e2d2597c177bb095da8f1ad794d69f76e8ac7ab1ba6340fdd0969e936-c7-minimal-x86_64-comps.xml.gz
-rw-r--r-- 1 root root 851584 Nov  3  2020 b6404d2de68763bab0d9fa3f8e1d6f5bc057b2c4a1919a89cc083d5dbc6efb19-primary.sqlite.bz2
-rw-r--r-- 1 root root  15455 Nov  3  2020 83b61f9495b5f728989499479e928e09851199a8846ea37ce008a3eb79ad84a0-c7-minimal-x86_64-comps.xml
-r--r--r-- 1 root root   3412 Nov  3  2020 TRANS.TBL

拷贝comps.xml，用于二次编辑使用

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[root@localhost ISO]# cp /mnt/cdrom/repodata/*-c7-minimal-x86_64-comps.xml /ISO/comps.xml
[root@localhost ISO]# cat /ISO/comps.xml
  <group>
    <id>core</id>
    <name>Core</name>
      <packagereq type="default">iwl6050-firmware</packagereq>
      <packagereq type="default">iwl7260-firmware</packagereq>
      <packagereq type="default">iwl7265-firmware</packagereq>
      <packagereq type="default">kernel-tools</packagereq>
      <packagereq type="default">libertas-sd8686-firmware</packagereq>
      <packagereq type="default">libertas-sd8787-firmware</packagereq>
      <packagereq type="default">libertas-usb8388-firmware</packagereq>

在kernel-tools处，添加新内核kernel-ml

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<packagereq type="default">iwl7260-firmware</packagereq>
<packagereq type="default">iwl7265-firmware</packagereq>
<packagereq type="default">kernel-ml</packagereq>
<packagereq type="default">kernel-tools</packagereq>
<packagereq type="default">libertas-sd8686-firmware</packagereq>
<packagereq type="default">libertas-sd8787-firmware</packagereq>
<packagereq type="default">libertas-usb8388-firmware</packagereq>

生成repodata

删除旧有的repodata，并通过刚才编辑的comps.xml文件重新生成新的repodata

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[root@localhost ISO]# rm -rf /ISO/repodata/
[root@localhost ISO]# cd /ISO
[root@localhost ISO]# createrepo -g comps.xml .
Spawning worker 0 with 510 pkgs
Spawning worker 1 with 510 pkgs
Spawning worker 2 with 510 pkgs
Spawning worker 3 with 510 pkgs
Spawning worker 4 with 509 pkgs
Spawning worker 5 with 509 pkgs
Spawning worker 6 with 509 pkgs
Spawning worker 7 with 509 pkgs
Workers Finished
Saving Primary metadata
Saving file lists metadata
Saving other metadata
Generating sqlite DBs
Sqlite DBs complete

生成ISO镜像

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[root@localhost ISO]# genisoimage -joliet-long -V CentOS7 -o CentOS-7.9-minimal-kernel-5.15.145.iso -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -R -J -v -cache-inodes -T -eltorito-alt-boot -e images/efiboot.img -no-emul-boot /ISO/
I: -input-charset not specified, using utf-8 (detected in locale settings)
genisoimage 1.1.11 (Linux)
Scanning /ISO/
Scanning /ISO/EFI
Scanning /ISO/EFI/BOOT
Scanning /ISO/EFI/BOOT/fonts
Excluded: /ISO/EFI/BOOT/fonts/TRANS.TBL
Excluded: /ISO/EFI/BOOT/TRANS.TBL
Excluded: /ISO/EFI/TRANS.TBL
Scanning /ISO/images
Scanning /ISO/images/pxeboot
Excluded: /ISO/images/pxeboot/TRANS.TBL
Excluded: /ISO/images/TRANS.TBL
Scanning /ISO/isolinux
Excluded by match: /ISO/isolinux/boot.cat
Excluded: /ISO/isolinux/TRANS.TBL
Scanning /ISO/LiveOS
Excluded: /ISO/LiveOS/TRANS.TBL
Scanning /ISO/Packages
Excluded: /ISO/Packages/TRANS.TBL
Excluded: /ISO/TRANS.TBL
Scanning /ISO/repodata
Using RPM_G000.;1 for  /RPM-GPG-KEY-CentOS-Testing-7 (RPM-GPG-KEY-CentOS-7)
...
...
 96.54% done, estimate finish Sat Dec 30 20:43:01 2023
 97.47% done, estimate finish Sat Dec 30 20:43:01 2023
 98.40% done, estimate finish Sat Dec 30 20:43:01 2023
 99.32% done, estimate finish Sat Dec 30 20:43:01 2023
Total translation table size: 123610
Total rockridge attributes bytes: 54615
Total directory bytes: 92160
Path table size(bytes): 140
Done with: The File(s)                             Block(s)    538383
Writing:   Ending Padblock                         Start Block 538493
Done with: Ending Padblock                         Block(s)    150
Max brk space used a3000
538643 extents written (1052 MB)

查看生成的镜像

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[root@localhost ISO]# ls -lrt *.iso
-rw-r--r-- 1 root root 1103140864 Dec 30 20:43 CentOS-7.9-minimal-kernel-5.15.145.iso

isohybrid则是syslinux的一个组件，可以将ISO镜像转换为可在BIOS和UEFI两种模式下启动的混合镜像。

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[root@localhost ISO]# isohybrid CentOS-7.9-minimal-kernel-5.15.145.iso
isohybrid: Warning: more than 1024 cylinders: 1053
isohybrid: Not all BIOSes will be able to boot this device

使用implantisomd5校验并写入md5值

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[root@localhost ISO]# implantisomd5 CentOS-7.9-minimal-kernel-5.15.145.iso
Inserting md5sum into iso image...
md5 = 25fdb7ee106de8b70c21100818b3d17a
Inserting fragment md5sums into iso image...
fragmd5 = 3a2efaa40d6c802865f4e1cdbb9e61b2737baa1815ab83dd2238fb77e335
frags = 20
Setting supported flag to 0

版本验证

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[root@192 develop]# uname -a
Linux 192.168.126.141 5.15.145-1.el7.x86_64 #1 SMP Sat Dec 23 12:17:11 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux

DVD版本镜像处理

上面Minimal镜像的处理，如果使用DVD版本，则处理时略有部分不同，首先看一下DVD版本相关的kernel包

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[root@localhost Packages]# ls -lrt kernel-*.rpm
-rw-rw-r-- 1 root root 52709940 Oct 20  2020 kernel-3.10.0-1160.el7.x86_64.rpm
-rw-rw-r-- 1 root root 18858740 Oct 20  2020 kernel-debug-devel-3.10.0-1160.el7.x86_64.rpm
-rw-rw-r-- 1 root root 18787608 Oct 20  2020 kernel-devel-3.10.0-1160.el7.x86_64.rpm
-rw-rw-r-- 1 root root  9449344 Oct 20  2020 kernel-headers-3.10.0-1160.el7.x86_64.rpm
-rw-rw-r-- 1 root root  8514900 Oct 20  2020 kernel-tools-3.10.0-1160.el7.x86_64.rpm
-rw-rw-r-- 1 root root  8405528 Oct 20  2020 kernel-tools-libs-3.10.0-1160.el7.x86_64.rpm
-rw-rw-r-- 1 root root  8413796 Oct 20  2020 kernel-abi-whitelists-3.10.0-1160.el7.noarch.rpm

相比Minimal镜像多出不少，因此需要将kernel-devel也做处理

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[root@localhost Packages]# rm -f kernel-3.10.0-1160.el7.x86_64.rpm kernel-devel-3.10.0-1160.el7.x86_64.rpm

将5.15.145版本内核和devel包放入/ISO/Packages/内

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[root@localhost Packages]# ls -lrt kernel-*.rpm
-rw-rw-r-- 1 root root 18858740 Oct 20  2020 kernel-debug-devel-3.10.0-1160.el7.x86_64.rpm
-rw-rw-r-- 1 root root  9449344 Oct 20  2020 kernel-headers-3.10.0-1160.el7.x86_64.rpm
-rw-rw-r-- 1 root root  8514900 Oct 20  2020 kernel-tools-3.10.0-1160.el7.x86_64.rpm
-rw-rw-r-- 1 root root  8405528 Oct 20  2020 kernel-tools-libs-3.10.0-1160.el7.x86_64.rpm
-rw-rw-r-- 1 root root  8413796 Oct 20  2020 kernel-abi-whitelists-3.10.0-1160.el7.noarch.rpm
-rw-r--r-- 1 root root 59958256 Dec 23 20:33 kernel-ml-5.15.145-1.el7.x86_64.rpm
-rw-r--r-- 1 root root 14438184 Dec 23 20:33 kernel-ml-devel-5.15.145-1.el7.x86_64.rpm

在编辑comps.xml文件时也有不同，需要在kernel-tools处同时添加kernel-ml、kernel-ml-devel

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[root@localhost Packages]# cp /mnt/cdrom/repodata/*-c7-x86_64-comps.xml /ISO/comps.xml

      <packagereq type="default">iwl6050-firmware</packagereq>
      <packagereq type="default">iwl7260-firmware</packagereq>
      <packagereq type="default">kernel-ml</packagereq>
      <packagereq type="default">kernel-ml-devel</packagereq>
      <packagereq type="default">kernel-tools</packagereq>
      <packagereq type="default">libsysfs</packagereq>
      <packagereq type="default">linux-firmware</packagereq>

另外DVD版本中携带了vdo相关包，其中vdo-6.1.3.23和kmod-kvdo-6.1.3.23依赖内核kernel-3.10.0-1160

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Running transaction
  Installing : kernel-3.10.0-1160.105.1.el7.x86_64                                 1/5 
  Installing : kmod-kvdo-6.1.3.23-5.el7.x86_64                                     2/5 
  Installing : libyaml-0.1.4-11.el7_0.x86_64                                       3/5 
  Installing : PyYAML-3.10-11.el7.x86_64                                           4/5 
  Installing : vdo-6.1.3.23-5.el7.x86_64                                           5/5

因此需要将comps.xml中如下两行删除

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<packagereq type="default">kmod-kvdo</packagereq>
<packagereq type="default">vdo</packagereq>

否则在DVD版本采用Gnome Desktop或者Server with GUI时会出现Error checking software selection。

其他步骤则与Minimal镜像一样，制作完毕后安装即可。

参考

1、https://access.redhat.com/documentation/zh-cn/red_hat_enterprise_linux/7/html/storage_administration_guide/vdo-integration
2、https://wiki.syslinux.org/wiki/index.php?title=Isohybrid
3、https://linux.die.net/man/1/implantisomd5
4、https://fedoraproject.org/wiki/How_to_use_and_edit_comps.xml_for_package_groups

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