Not only does the root filesystem needs to be configured, but the Linux kernel also needs to be specifically configured with all the features required by systemd. There is an extensive list of kernel configuration variables in the systemd source README file. As an example, to extend the minimal kernel configuration that we will introduce in the Reducing the Linux kernel image size recipe later in this chapter, for the Wandboard to support systemd, we would need to add the following configuration changes in the arch/arm/configs/wandboard-custom-minimal_defconfig file:

+CONFIG_FHANDLE=y 
+CONFIG_CGROUPS=y 
+CONFIG_SECCOMP=y 
+CONFIG_NET=y 
+CONFIG_UNIX=y 
+CONFIG_INET=y 
+CONFIG_AUTOFS4_FS=y 
+CONFIG_TMPFS=y 
+CONFIG_TMPFS_POSIX_ACL=y 
+CONFIG_SCHEDSTATS=y 
-# CONFIG_PROC_SYSCTL is not set 
-# CONFIG_PROC_PAGE_MONITOR is not set 
-# CONFIG_SYSFS is not set 

The default kernel configuration provided for the Wandboard will launch a core-image-minimal image of systemd just fine.