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Resolving a dracut error about the systemd-pcrphase module and tpm2-tss - Amazon Linux 2023
CauseResolution

Resolving a dracut error about the systemd-pcrphase module and tpm2-tss

When you rebuild the initramfs on AL2023 (for example, by running sudo dracut --force or as part of a kernel package installation), dracut might fail with the following error:

$ sudo dracut --force
dracut[E]: Module 'systemd-pcrphase' depends on 'tpm2-tss', which can't be installed

This error can occur even when the tpm2-tss package is already installed on your instance.

Cause

The systemd-pcrphase dracut module measures boot phases into a Trusted Platform Module (TPM). In addition to tpm2-tss, the module also requires the tpm2-tools and tpm2-tss-fapi packages to be present before it can be included in the initramfs. These packages are not installed by default on AL2023, so installing tpm2-tss on its own does not resolve the error.

Resolution

Install the missing tpm2 packages, and then rebuild the initramfs.

  1. Install the tpm2-tss-fapi and tpm2-tools packages:

    $ sudo dnf install tpm2-tss-fapi tpm2-tools

  2. Rebuild the initramfs. The command now completes without the systemd-pcrphase error:

    $ sudo dracut --force
Note

AL2023 does not install the tpm2-tools and tpm2-tss-fapi packages by default, and there are no plans to include them in the default AL2023 AMIs. If you need the systemd-pcrphase dracut module, install these packages manually as shown above.