On Sat, Aug 23, 2025 at 03:12:48PM +0300, Jarkko Sakkinen wrote: > Hi > > As of today can we possibly do this: > > 1. drivers/char/tpm (C code) > 2. drivers/char/tpm/protocol (imported tpm2_protocol) > > ? > > And then build FFI from C to Rust for building commands that we need > today etc. > > There's one particular challenge where this could help: early boot code > for D-RTM (i.e., Trenchboot) as given my crate is just a thing in stack > with no deps, it could be linked also to that payload. > > This would be much better integration step for TPM2 than having a > separate driver on Rust side. We could start with tpm2-cmd1/cmd2, then > move on to tpm2-space.c i.e. get all structural processing inside Rust. > > tpm2_protocol is light on definitions and should not need any kernel > specific Rust shenanigans. > > Consider it as value like integer but just a bit more complex internaal > represention but in the end it is just a value on stack. > > My goal with tpm2_protocol is to have ACPICA alike model of imports as > the crate is driven by TCG spec updates and it is very likely to be > also used by TPM-RS (also via import style process). The source code since 0.10.0 version has been relocated here:
https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/tpm2-protocol.git The representation of commands and responses defined is pretty well high-lighted by https://bsky.app/profile/jarkk0.bsky.social/post/3lx2n2uvxos2h I'm also working on a test that measures the estimated compile time size and realized run-time size (suggested by Philip Tricca) so that we know where we are at on stack usage. I've started to optimize it after development phase with some low-hanging fruit cut already in 0.10.0 but this work is barely starting [1]. There's also a kselftest compatible test that can be run with "make test" in the repo using only rustc (build + run circa 2 seconds on my laptop). [1] https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/tpm2-protocol.git/commit/?id=cd6641bf9e8c8fde8726bece9eb6cdc630d893c2 BR, Jarkko
