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List:       linux-keyrings
Subject:    Re: [PATCH v4] Documentation: tpm_tis
From:       "Jarkko Sakkinen" <jarkko () kernel ! org>
Date:       2024-03-24 2:14:36
Message-ID: D01M8YKG5ZG0.287OTMCUU2KP5 () kernel ! org
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On Sat Mar 23, 2024 at 8:40 PM EET, Jarkko Sakkinen wrote:
> > Would it be worth clarifying here that one of those interfaces is 
> > defined in the Mobile TPM specification, which also refers to its 
> > interface as the CRB interface. In the past, this has caused great 
> > confusion when working with individuals from the embedded community, 
> > e.g., Arm. The Mobile TPM CRB interface, which can also be found being 
> > used by some generations of AMD fTPM, is a doorbell style interface 
> > using general-purpose memory. I would also point out that the Mobile TPM 
> > CRB interface does not provide for the concept of localities.
>
> I don't necessarily disagree but it is out of scope for this. I'm not
> sure tho why "mobile" CRB would ever need that sort of separate
> dicussion.
>
> Some CRB implementations have localities some don't, and also fTPM
> implementations on x86 vary, no need to state that separately for
> mobile.

I.e. the variance exist but it is not "mobile" specific.

E.g. when I developed tpm_crb in 2014 at that time Intel PTT only
had a single locality (AFAIK later multiple localities were added
to support TXT).

In all cases this tpm_crb discussion is not really part of tpm_tis
discussion.

BR, Jarkko

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