Systemd spends much time about 30 seconds for every unit

Hi all,

I am working on virtualization on armv8 platform and encountered a complex problem. From the below boot log, we can find:

Every unit init need about 30 seconds.
status_printf function doesn't work. [no status_welcome print and no manager_status_printf print]
I'm trying to use systemd.log_level=debug systemd.log_target=console console=ttymxc0,115200 earlycon=ec_imx6q,0x30860000,115200 to show more debug info, however the boot stoped at systemd[1]: System time before build time, advancing clock.

[    2.478912] systemd[1]: System time before build time, advancing clock.
[    2.499714] systemd[1]: systemd 237 running in system mode. (+PAM -AUDIT -SELINUX +IMA -APPARMOR +SMACK +SYSVINIT +UTMP -LIBCRYPTSETUP -GCRYPT -GNUTLS +ACL +XZ -LZ4 -SECCOMP +BLKID -ELFUTILS +KMOD -ID)
[    2.520807] systemd[1]: Detected architecture arm64.
[   33.892575] systemd[1]: Set hostname to <imx8mqevk>.
[   64.632124] systemd[1]: File /lib/systemd/system/systemd-journald.service:35 configures an IP firewall (IPAddressDeny=any), but the local system does not support BPF/cgroup based firewalling.
[   64.648846] systemd[1]: Proceeding WITHOUT firewalling in effect! (This warning is only shown for the first loaded unit using IP firewalling.)
[   64.771322] random: systemd: uninitialized urandom read (16 bytes read)
[   64.777950] systemd[1]: Reached target Swap.
[   95.329244] random: systemd: uninitialized urandom read (16 bytes read)
[   95.337197] systemd[1]: Created slice User and Session Slice.
[  126.049246] random: systemd: uninitialized urandom read (16 bytes read)
[  126.055962] systemd[1]: Started Dispatch Password Requests to Console Directory Watch.
[  156.769223] random: systemd: uninitialized urandom read (16 bytes read)
[  156.776389] systemd[1]: Created slice System Slice.
[  187.489398] random: systemd: uninitialized urandom read (16 bytes read)
[  187.496097] systemd[1]: Listening on Journal Audit Socket.
[  218.209185] random: systemd: uninitialized urandom read (16 bytes read)
[  218.216387] systemd[1]: Created slice system-getty.slice.
[  248.929177] random: systemd: uninitialized urandom read (16 bytes read)
[  248.936006] systemd[1]: Listening on Journal Socket (/dev/log).
[  279.649275] random: systemd: uninitialized urandom read (16 bytes read)
[  279.655957] systemd[1]: Listening on Network Service Netlink Socket.
[  310.369169] random: systemd: uninitialized urandom read (16 bytes read)
[  310.375751] systemd[1]: Reached target Slices.
[  341.089186] random: systemd: uninitialized urandom read (16 bytes read)
[  341.095860] systemd[1]: Listening on udev Kernel Socket.
[  371.809808] systemd[1]: Created slice system-serial\x2dgetty.slice.
[  402.529343] systemd[1]: Listening on /dev/initctl Compatibility Named Pipe.
[  433.249462] systemd[1]: Listening on Journal Socket.
[  463.971364] systemd[1]: Mounting POSIX Message Queue File System...
[  494.698279] systemd[1]: Mounting Temporary Directory (/tmp)...
[  525.411581] systemd[1]: Starting Remount Root and Kernel File Systems...
[  525.448466] EXT4-fs (mmcblk0p2): re-mounted. Opts: (null)
[  556.138486] systemd[1]: Mounting Kernel Debug File System...
[  586.851539] systemd[1]: Starting Setup Virtual Console...
[  617.571697] systemd[1]: Mounting Huge Pages File System...
[  648.289259] systemd[1]: Reached target Remote File Systems.
[  679.019075] systemd[1]: Starting Load Kernel Modules...
[  709.729485] systemd[1]: Started Forward Password Requests to Wall Directory Watch.
[  740.449217] systemd[1]: Reached target Paths.
[  771.169198] systemd[1]: Reached target Host and Network Name Lookups.
[  801.889470] systemd[1]: Listening on Syslog Socket.
[  832.611466] systemd[1]: Starting Journal Service...

Thank you for your support.

Best regards,
shuyi cheng