Missing kernel module builtin TPM in Buster installer

[Sébastien BRUCKERT <sebastien.bruckert@smile.fr>]

Hello,

I am currently trying to install Debian Buster 10.7 on custom hardware
(amd64) with a TPM. I need to access that device: /dev/tpm0  at
installation time (with a preseed script).

In Debian Stretch, the installer kernel has these module builtin
(viewed from initrd, from the .iso):

lib/modules/4.9.0-11-amd64/modules.builtin:kernel/drivers/char/tpm/tpm.ko
lib/modules/4.9.0-11-amd64/modules.builtin:kernel/drivers/char/tpm/tpm_tis_core.ko
lib/modules/4.9.0-11-amd64/modules.builtin:kernel/drivers/char/tpm/tpm_tis.ko

However, in Debian Buster 10.7, these are not present, in the netinst
ISO or in the DVD ISO. Not in builtin, not in external.

Is there any history of why this has changed? How is it possible to
bring the module back? Is there a way to manually compile that module
for that specific kernel? Or better, to put my own kernel, and create
the udebs corresponding to it?

Thank you