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From: Stefan Berger <stefanb@linux.vnet.ibm.com>
To: "Jarkko Sakkinen" <jarkko.sakkinen@linux.intel.com>,
	"Peter Hüwe" <PeterHuewe@gmx.de>
Cc: Ashley Lai <ashley@ashleylai.com>,
	Marcel Selhorst <tpmdd@selhorst.net>,
	tpmdd-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org,
	josh@joshtriplett.org, christophe.ricard@gmail.com,
	jason.gunthorpe@obsidianresearch.com, linux-api@vger.kernel.org,
	trousers-tech@lists.sourceforge.net
Subject: Re: [PATCH] tpm, tpm_tis: fix TPM 2.0 probing
Date: Tue, 10 Feb 2015 07:16:32 -0500	[thread overview]
Message-ID: <54D9F6A0.9010905@linux.vnet.ibm.com> (raw)
In-Reply-To: <20150209083947.GC29987@intel.com>

On 02/09/2015 03:39 AM, Jarkko Sakkinen wrote:
> On Mon, Feb 09, 2015 at 12:08:46AM +0100, Peter Hüwe wrote:
>> Am Mittwoch, 4. Februar 2015, 15:21:09 schrieb Jarkko Sakkinen:
>>> If during transmission system error was returned, the logic was to
>>> incorrectly deduce that chip is a TPM 1.x chip. This patch fixes this
>>> issue. Also, this patch changes probing so that message tag is used as the
>>> measure for TPM 2.x, which should be much more stable.
>> Is it aware that some TPMs may respond with 0x00C1 as TAG for TPM1.2 commands?
> I guess none of the TPM 1.2 command answer with the tag 0x8002?


FYI: pdf page 26 , section 6.1 explains the predictable return value for 
a TPM1.2 command seen by a TPM2

http://www.trustedcomputinggroup.org/files/static_page_files/8C68ADA8-1A4B-B294-D0FC06D3773F7DAA/TPM%20Rev%202.0%20Part%203%20-%20Commands%2001.16-code.pdf

Following this:

Sending a TPM1.2 command to a TPM2 should return a TPM1.2 header (tag = 
0xc4) and error code (TPM_BADTAG = 0x1e)

Sending a TPM 2 command to a TPM 2 will give a TPM 2 tag in the header.
Sending a TPM 2 command to a TPM 1.2 will give a TPM 1.2 tag in the 
header and an error code.


    Stefan


  reply	other threads:[~2015-02-10 12:16 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-04 14:21 Jarkko Sakkinen
2015-02-08 23:08 ` Peter Hüwe
2015-02-09  8:39   ` Jarkko Sakkinen
2015-02-10 12:16     ` Stefan Berger [this message]
2015-02-10 12:50       ` Jarkko Sakkinen
2015-02-11 18:47         ` Stefan Berger
2015-02-12  5:25           ` Jarkko Sakkinen

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