安装guest additions需要 kernel headers, openSUSE是没有kernel-headers的，对应的是kernel-devel。
执行zypper install kernel-desktop-devel即可。
paul@localhost:~> sudo zypper install kernel-desktop-devel
Loading repository data...
Reading installed packages...
'kernel-desktop-devel' not found in package names. Trying capabilities.
Resolving package dependencies...
The following 18 NEW packages are going to be installed:
gcc gcc7 glibc-devel kernel-default-devel kernel-devel kernel-macros libasan4
libatomic1 libcilkrts5 libelf-devel libitm1 liblsan0 libmpx2 libmpxwrappers2
libtsan0 libubsan0 linux-glibc-devel zlib-devel
The following recommended package was automatically selected:
gcc
18 new packages to install.
Overall download size: 43.1 MiB. Already cached: 0 B. After the operation,
additional 145.2 MiB will be used.
Continue? [y/n/v/...? shows all options] (y): y
Retrieving package libasan4-7.5.0+r278197-lp152.2.46.x86_64
(1/18), 357.4 KiB ( 1.3 MiB unpacked)
Retrieving: libasan4-7.5.0+r278197-lp152.2.46.x86_64.rpm ......[done (1021 B/s)]
Retrieving package libatomic1-9.2.1+r274709-lp152.1.107.x86_64
(2/18), 22.1 KiB ( 26.1 KiB unpacked)
Retrieving: libatomic1-9.2.1+r274709-lp152.1.107.x86_64.rpm ..............[done]
Retrieving package libcilkrts5-7.5.0+r278197-lp152.2.46.x86_64
(3/18), 60.7 KiB (120.1 KiB unpacked)
Retrieving: libcilkrts5-7.5.0+r278197-lp152.2.46.x86_64.rpm ...[done (1018 B/s)]
Retrieving package libitm1-9.2.1+r274709-lp152.1.107.x86_64
(4/18), 40.3 KiB (110.4 KiB unpacked)
Retrieving: libitm1-9.2.1+r274709-lp152.1.107.x86_64.rpm ....[done (15.0 KiB/s)]
Retrieving package liblsan0-9.2.1+r274709-lp152.1.107.x86_64
(5/18), 147.0 KiB (349.2 KiB unpacked)
Retrieving: liblsan0-9.2.1+r274709-lp152.1.107.x86_64.rpm ..[done (105.9 KiB/s)]
Retrieving package libmpx2-8.2.1+r264010-lp152.2.126.x86_64
(6/18), 19.1 KiB ( 18.3 KiB unpacked)
Retrieving: libmpx2-8.2.1+r264010-lp152.2.126.x86_64.rpm .................[done]
Retrieving package libmpxwrappers2-8.2.1+r264010-lp152.2.126.x86_64
(7/18), 17.8 KiB ( 14.2 KiB unpacked)
Retrieving: libmpxwrappers2-8.2.1+r264010-lp152.2.126.x86_64.r[done (3.8 KiB/s)]
Retrieving package libtsan0-9.2.1+r274709-lp152.1.107.x86_64
(8/18), 298.3 KiB (965.2 KiB unpacked)
Retrieving: libtsan0-9.2.1+r274709-lp152.1.107.x86_64.rpm ...[done (15.1 KiB/s)]
Retrieving package libubsan0-7.5.0+r278197-lp152.2.46.x86_64
(9/18), 134.0 KiB (305.3 KiB unpacked)
Retrieving: libubsan0-7.5.0+r278197-lp152.2.46.x86_64.rpm ................[done]
Retrieving package linux-glibc-devel-5.3-lp152.1.1.x86_64
(10/18), 1.0 MiB ( 4.4 MiB unpacked)
Retrieving: linux-glibc-devel-5.3-lp152.1.1.x86_64.rpm .......[done (1.5 MiB/s)]
Retrieving package glibc-devel-2.26-lp152.25.10.x86_64
(11/18), 754.6 KiB ( 2.9 MiB unpacked)
Retrieving: glibc-devel-2.26-lp152.25.10.x86_64.rpm ......................[done]
Retrieving package zlib-devel-1.2.11-lp152.7.8.x86_64
(12/18), 110.1 KiB (385.9 KiB unpacked)
Retrieving: zlib-devel-1.2.11-lp152.7.8.x86_64.rpm .......................[done]
Retrieving package gcc7-7.5.0+r278197-lp152.2.46.x86_64
(13/18), 19.7 MiB ( 72.7 MiB unpacked)
Retrieving: gcc7-7.5.0+r278197-lp152.2.46.x86_64.rpm .........[done (2.8 MiB/s)]
Retrieving package libelf-devel-0.168-lp152.5.103.x86_64
(14/18), 727.6 KiB ( 2.1 MiB unpacked)
Retrieving: libelf-devel-0.168-lp152.5.103.x86_64.rpm ........[done (1.3 MiB/s)]
Retrieving package gcc-7-lp152.4.114.x86_64
(15/18), 10.1 KiB ( 0 B unpacked)
Retrieving: gcc-7-lp152.4.114.x86_64.rpm .................................[done]
Retrieving package kernel-macros-5.3.18-lp152.20.7.1.noarch
(16/18), 1.6 MiB ( 21.1 KiB unpacked)
Retrieving: kernel-macros-5.3.18-lp152.20.7.1.noarch.rpm ...[done (147.9 KiB/s)]
Retrieving package kernel-devel-5.3.18-lp152.20.7.1.noarch
(17/18), 13.5 MiB ( 54.9 MiB unpacked)
Retrieving: kernel-devel-5.3.18-lp152.20.7.1.noarch.rpm ......[done (2.6 MiB/s)]
Retrieving package kernel-default-devel-5.3.18-lp152.20.7.1.x86_64
(18/18), 4.7 MiB ( 4.6 MiB unpacked)
Retrieving: kernel-default-devel-5.3.18-lp152.20.7.1.x86_64.rp[done (2.3 MiB/s)]
Checking for file conflicts: .............................................[done]
( 1/18) Installing: libasan4-7.5.0+r278197-lp152.2.46.x86_64 .............[done]
( 2/18) Installing: libatomic1-9.2.1+r274709-lp152.1.107.x86_64 ..........[done]
( 3/18) Installing: libcilkrts5-7.5.0+r278197-lp152.2.46.x86_64 ..........[done]
( 4/18) Installing: libitm1-9.2.1+r274709-lp152.1.107.x86_64 .............[done]
( 5/18) Installing: liblsan0-9.2.1+r274709-lp152.1.107.x86_64 ............[done]
( 6/18) Installing: libmpx2-8.2.1+r264010-lp152.2.126.x86_64 .............[done]
( 7/18) Installing: libmpxwrappers2-8.2.1+r264010-lp152.2.126.x86_64 .....[done]
( 8/18) Installing: libtsan0-9.2.1+r274709-lp152.1.107.x86_64 ............[done]
( 9/18) Installing: libubsan0-7.5.0+r278197-lp152.2.46.x86_64 ............[done]
(10/18) Installing: linux-glibc-devel-5.3-lp152.1.1.x86_64 ...............[done]
(11/18) Installing: glibc-devel-2.26-lp152.25.10.x86_64 ..................[done]
(12/18) Installing: zlib-devel-1.2.11-lp152.7.8.x86_64 ...................[done]
(13/18) Installing: gcc7-7.5.0+r278197-lp152.2.46.x86_64 .................[done]
(14/18) Installing: libelf-devel-0.168-lp152.5.103.x86_64 ................[done]
(15/18) Installing: gcc-7-lp152.4.114.x86_64 .............................[done]
(16/18) Installing: kernel-macros-5.3.18-lp152.20.7.1.noarch .............[done]
(17/18) Installing: kernel-devel-5.3.18-lp152.20.7.1.noarch ..............[done]
(18/18) Installing: kernel-default-devel-5.3.18-lp152.20.7.1.x86_64 ......[done]
安装完成后再插入VBoxGuestAdditions.iso，会自动跳出，点击运行安装，完成后重启。
如果是在没有安装kernel devel的情况下运行会提示以下信息。
Verifying archive integrity... All good.
Uncompressing VirtualBox 6.1.0 Guest Additions for Linux........
VirtualBox Guest Additions installer
Copying additional installer modules ...
Installing additional modules ...
VirtualBox Guest Additions: Starting.
VirtualBox Guest Additions: Building the VirtualBox Guest Additions kernel
modules. This may take a while.
VirtualBox Guest Additions: To build modules for other installed kernels, run
VirtualBox Guest Additions: /sbin/rcvboxadd quicksetup
VirtualBox Guest Additions: or
VirtualBox Guest Additions: /sbin/rcvboxadd quicksetup all
VirtualBox Guest Additions: Kernel headers not found for target kernel
5.3.18-lp152.20.7-default. Please install them and execute
/sbin/rcvboxadd setup
VirtualBox Guest Additions: Running kernel modules will not be replaced until
the system is restarted
Press Return to close this window...
按Enter键关闭窗口后 执行命令sudo zypper install kernel-desktop-devel。
安装完成后再执行以下命令重新设置VBoxGuestAdditions.
paul@localhost:~> sudo /sbin/rcvboxadd setup
VirtualBox Guest Additions: Starting.
VirtualBox Guest Additions: Building the VirtualBox Guest Additions kernel
modules. This may take a while.
VirtualBox Guest Additions: To build modules for other installed kernels, run
VirtualBox Guest Additions: /sbin/rcvboxadd quicksetup
VirtualBox Guest Additions: or
VirtualBox Guest Additions: /sbin/rcvboxadd quicksetup all
VirtualBox Guest Additions: Building the modules for kernel
5.3.18-lp152.20.7-default.
dracut: Executing: /usr/bin/dracut -f --kver 5.3.18-lp152.20.7-default
dracut: dracut module 'biosdevname' will not be installed, because command 'biosdevname' could not be found!
dracut: *** Including module: bash ***
dracut: *** Including module: systemd ***
dracut: *** Including module: systemd-initrd ***
dracut: *** Including module: i18n ***
dracut: *** Including module: drm ***
dracut: *** Including module: plymouth ***
dracut: *** Including module: btrfs ***
dracut: *** Including module: kernel-modules ***
dracut: *** Including module: kernel-modules-extra ***
dracut: *** Including module: resume ***
dracut: *** Including module: rootfs-block ***
dracut: *** Including module: suse-btrfs ***
dracut: *** Including module: suse-xfs ***
dracut: *** Including module: terminfo ***
dracut: *** Including module: udev-rules ***
dracut: Skipping udev rule: 40-redhat.rules
dracut: Skipping udev rule: 50-firmware.rules
dracut: Skipping udev rule: 50-udev.rules
dracut: Skipping udev rule: 91-permissions.rules
dracut: Skipping udev rule: 80-drivers-modprobe.rules
dracut: *** Including module: dracut-systemd ***
dracut: *** Including module: haveged ***
dracut: *** Including module: ostree ***
dracut: *** Including module: usrmount ***
dracut: *** Including module: base ***
dracut: *** Including module: fs-lib ***
dracut: *** Including module: shutdown ***
dracut: *** Including module: suse ***
dracut: *** Including module: suse-initrd ***
dracut: *** Including modules done ***
dracut: *** Installing kernel module dependencies ***
dracut: *** Installing kernel module dependencies done ***
dracut: *** Resolving executable dependencies ***
dracut: *** Resolving executable dependencies done ***
dracut: *** Hardlinking files ***
dracut: *** Hardlinking files done ***
dracut: *** Stripping files ***
dracut: *** Stripping files done ***
dracut: *** Generating early-microcode cpio image ***
dracut: *** Constructing GenuineIntel.bin ***
dracut: *** Store current command line parameters ***
dracut: Stored kernel commandline:
dracut: resume=UUID=c847c324-b399-4a7a-b798-499473b55cbe
dracut: root=UUID=908c1b9b-efdb-41b5-b61b-1d956ba19f7d rootfstype=btrfs rootflags=rw,relatime,space_cache,subvolid=268,subvol=/@/.snapshots/1/snapshot,subvol=@/.snapshots/1/snapshot
dracut: *** Creating image file '/boot/initrd-5.3.18-lp152.20.7-default' ***
dracut: *** Creating initramfs image file '/boot/initrd-5.3.18-lp152.20.7-default' done ***
VirtualBox Guest Additions: Running kernel modules will not be replaced until
the system is restarted
完成后重启。
paul@localhost:~> sudo reboot
进入系统后口能自适应窗大小自动调整分辨率，也可以全屏。