Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH v3 2/2] ftpm: add documentation for ftpm driver
To:     Sasha Levin <sashal@kernel.org>, peterhuewe@gmx.de,
        jarkko.sakkinen@linux.intel.com, jgg@ziepe.ca
Cc:     corbet@lwn.net, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org, linux-integrity@vger.kernel.org,
        linux-kernel@microsoft.com, thiruan@microsoft.com,
        bryankel@microsoft.com
References: <20190415155636.32748-1-sashal@kernel.org>
 <20190415155636.32748-3-sashal@kernel.org>
From:   "Enrico Weigelt, metux IT consult" <lkml@metux.net>
Organization: metux IT consult
Message-ID: <b2c1b45e-515d-1d91-e3d9-5f9078078cae@metux.net>
Date:   Wed, 17 Apr 2019 14:23:13 +0200
User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.2.1
MIME-Version: 1.0
In-Reply-To: <20190415155636.32748-3-sashal@kernel.org>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 15.04.19 17:56, Sasha Levin wrote:

Hi,

> +The driver acts as a thin layer that passes commands to and from a TPM> +implemented in firmware. The driver itself doesn't contain much logic
and is> +used more like a dumb pipe between firmware and kernel/userspace.
Is that TPM already used in production or yet an PoC ?
IOW: can the protocol be changed ?

If so, I'd prefer using 9P for that. This already proven well, not just
for grid computing (where it originally came from), but also in things
like virtio, etc.

In general, many of the hardware/chip interfaces out there basically
deal with either either passing around some data packets or streams,
or reading/setting some attributes. But everybody seems to do that part
in his own special way - that takes up a big share of the driver
development resources and final code - and that needs to be repeated
for each OS. In many, many cases a standard protocol like 9P could
already provide this - if folks would just use it :p

Therefore, I'm really a strong supporter of the idea of using 9P
for this.

In your case, you could design the highlevel TPM interface like with
a tcp stream / socket or a synthetic filesystem, and for the lowlevel
part just like kvm does w/ virtio.

In case you have no experience w/ 9P+friends, feel free to ask,
I'll to my best to explain it :)


--mtx

-- 
Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering
info@metux.net -- +49-151-27565287