Re: TPM2 on AMD Rizen (fTPM)

Hello again,

First thing: apologies for my email client messing up with charset encoding, hope is fixed now.

Second, I add some detail/information.

The machine is a bare metal on Hetzner, I do not have many details, it’s an AMD Ryzen 9 3900 12-Core/24-Threads toy with some motherboard using American Megatrends firmware; unfortunately I have very limited access to the console (one hour upon request…).

As said the “fTPM” has been enabled in the firmare, and I also tried all the possible combinations of the settings in the firmware which could seem anyhow pertinent (SCM etc).

The kernel is a custom-built one, simply stripped down to include statically all used devices/modules and drop the rest, compiled with -march=native as all the userland; no problem in rebooting with the GENERIC kernel, but I cannot imagine how it could help.

Should any additional information be useful to give me some advice just ask, the machine is there to experiment.

Thanks for any advice,

A.


> On 3 Feb 2024, at 18:21, Andrea Cocito <andrea@cocito.eu> wrote:
> 
> Hi,
> 
> I’m trying to enable TPM support on a box in order to experiment a bit with it, but the driver does not seem to load and/or see the device.
> 
> In the firmware the “fTPM” option has been enabled, tried both with SCM enabled and disabled, basically I tried all the possible firmware options combinations with no success.
> 
> I have tpm_load=“YES” in /boot/loader.conf and also tried the hints suggested by the man page is /boot/device.hints
> 
> No way to have the tpm? device(s) appear, the best I achieved so far on dmesg in a verbose boot is:
> …
> Preloaded elf obj module "/boot/kernel.old/geom_mirror.ko" at 0xffffffff8196d8c0.
> Preloaded elf obj module "/boot/kernel.old/tpm.ko" at 0xffffffff8196dfb0.
> …
> tpm0 failed to probe at iomem 0xfffffffffed40000-0xfffffffffed44fff on isa0
> tpm1 failed to probe at iomem 0xfffffffffed40000-0xfffffffffed40fff on isa0
> …
> 
> I am all but an expert about TPM architecture (this is why I am willing to play with it), but as far as I understand AMD’s fTPM is a TPM2 built into the CPU, I have no idea on which bus it should be seen and how.
> 
> So my questions are:
> - Is AMD’s fTPM supported at all by the driver?
> - Am I missing something very obvious?
> 
> I have been digging around for information quite a bit, but there does not seem to be much information around. Hope I am hitting the correct list (accept my apologies if it is not).
> 
> Thanks in advance for any advice.