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For AKS-CC, after these changes:

  • The Guest image file is 2Mi smaller.
  • 10 of the units printed by "systemd-analyze blame" have been removed.
  • The number of units loaded by systemd is smaller by 74.

For AKS-Kata, after these changes:

  • The Guest image file is 2Mi smaller.
  • 4 of the units printed by "systemd-analyze blame" have been removed.
  • The number of units loaded by systemd is smaller by 63.

Apparently there was a typo in that file name - the actual name is:

systemd-tmpfiles-clean.timer

systemd-tmpfiles-clean.timer will be deleted in a future commit.

Signed-off-by: Dan Mihai <[email protected]>
Delete systemd *.timer files, in addition to *.service and *.socket.

Signed-off-by: Dan Mihai <[email protected]>
Delete:
- systemd-tmpfiles-clean.timer
- systemd-tmpfiles-clean.service
- systemd-tmpfiles-setup-dev.service
- systemd-tmpfiles-setup-dev-early.service
- systemd-tmpfiles

systemd-tmpfiles-setup.service was already deleted.

Signed-off-by: Dan Mihai <[email protected]>
Delete *.path files, in addition to *.service, *.socket, and *.timer.

Signed-off-by: Dan Mihai <[email protected]>
Delete:
- systemd-ask-password-console.path
- systemd-ask-password-console.service
- systemd-ask-password-wall.path
- systemd-ask-password-wall.service
- systemd-tty-ask-password-agent

Passwords are not used on Kata Guest VMs.

Signed-off-by: Dan Mihai <[email protected]>
Delete systemd binaries that have the same name as unit files
that are being deleted.

The following binaries get deleted after this change:
- systemd-journald
- systemd-random-seed
- systemd-timesyncd
- systemd-update-utmp

Signed-off-by: Dan Mihai <[email protected]>
Delete:
- [email protected]
- systemd-pcrfs-root.service
- systemd-pcrlock-firmware-code.service
- systemd-pcrlock-firmware-config.service
- systemd-pcrlock-file-system.service
- systemd-pcrlock-machine-id.service
- systemd-pcrlock-make-policy.service
- systemd-pcrlock-secureboot-authority.service
- systemd-pcrlock-secureboot-policy.service
- systemd-pcrmachine.service
- systemd-pcrphase.service
- systemd-pcrphase-initrd.service
- systemd-pcrphase-sysinit.service
- systemd-pcrextend.socket
- [email protected]
- systemd-pcrextend

PCRs are not used on the Guest VMs.

Signed-off-by: Dan Mihai <[email protected]>
Delete:
- systemd-journald-audit.socket
- systemd-journal-catalog-update.service
- systemd-journal-flush.service
- [email protected]
- [email protected]
- journalctl

Other journal files were already deleted.

Signed-off-by: Dan Mihai <[email protected]>
Delete blk-availability.service and the blkdeactivate binary. They
are not needed on the Guest VMs.

Signed-off-by: Dan Mihai <[email protected]>
Not needed on a Kata Guest VM.

Signed-off-by: Dan Mihai <[email protected]>
Deleted files:
- systemd-logind.service
- systemd-logind

Not needed on the Guest VM.

Signed-off-by: Dan Mihai <[email protected]>
Not needed on Guest VMs.

Deleting this service disables modprobe@efi_pstore.service too.

Signed-off-by: Dan Mihai <[email protected]>
Deleted files:
- systemd-sysupdate.service
- systemd-sysupdate.timer
- systemd-sysupdate-reboot.timer
- systemd-sysupdate-reboot.service
- systemd-sysupdate

Guest VMs are not being updated this way.

Signed-off-by: Dan Mihai <[email protected]>
Delete:
- systemd-network-generator.service
- systemd-network-generator

Generating network configuration based on kernel command line arguments
is currently not supported for Guest VMs.

Signed-off-by: Dan Mihai <[email protected]>
Deleted files:
- systemd-tpm2-setup.service
- systemd-tpm2-setup-early.service
- systemd-tpm2-setup

TPM is not used on Guest VMs.

Signed-off-by: Dan Mihai <[email protected]>
Delete *.mount files in addition to other systemd files.

Signed-off-by: Dan Mihai <[email protected]>
There are no userspace filesystems on the Guest VMs, so no need to mount
the FUSE control filesystem.

Note that the FUSE protocol used by virtio-fs uses a server on the
Host, and doesn't depend on the FUSE control filesystem on the Guest.

Without sys-fs-fuse-connections.mount, [email protected] gets
disabled too.

Signed-off-by: Dan Mihai <[email protected]>
This mount was not functional due to missing CONFIG_CONFIGFS_FS in the
Guest kernel.

Deleting sys-kernel-config.mount also disables [email protected].

Signed-off-by: Dan Mihai <[email protected]>
Delete:
- systemd-update-utmp-runlevel.service
- systemd-update-utmp
in addition to systemd-update-utmp.service that was already deleted
before this commit.

systemd-update-utmp-runlevel.service depends on /var/log/wtmp. However,
systemd-tmpfiles-setup.service was already deleted, so /var/log/wtmp
was not present.

Signed-off-by: Dan Mihai <[email protected]>
Deleted files:
- systemd-vconsole-setup.service
- systemd-vconsole-setup

The Guest VM doesn't use virtual consoles.

Signed-off-by: Dan Mihai <[email protected]>
@danmihai1 danmihai1 requested review from a team as code owners January 29, 2025 02:33
@danmihai1 danmihai1 added the upstream/not-needed PRs that will not be upstreamed (e.g. internal) label Jan 29, 2025
@manuelh-dev manuelh-dev merged commit 08aceb8 into msft-main Feb 5, 2025
48 of 59 checks passed
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3 participants