On Wed, Feb 11, 2015 at 01:47:01PM -0500, Stefan Berger wrote: > On 02/10/2015 07:50 AM, Jarkko Sakkinen wrote: > >On Tue, Feb 10, 2015 at 07:16:32AM -0500, Stefan Berger wrote: > >>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. > >Thank you for the information. Do you think that for some reason > >tpm2_probe() shoould instead check that value is not this error > >instead of checking that tag is 0x80002? > > Following your path, you are checking for TPM2_ST_NO_SESSION (0x8001), which > looks correct to me. A TPM1.2 would never send this tag back. OK, perfect :) > Stefan /Jarkko -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
