[EDK2 tcg2] TCG2 variable TCG2_DEVICE_DETECTION_NAME does not work as expected?

[EDK2 tcg2] TCG2 variable TCG2_DEVICE_DETECTION_NAME does not work as expected?

[winddy]

Hi experts, 
    Now I am studying latest tcg2 modules, and I guess there may be something wrong with variable (TCG2_DEVICE_DETECTION_NAME, gTcg2ConfigFormSetGuid). 
    This variable is used to save TPM device type(TPM1.2, TPM2.0, or not present) detected at PEI. The save action is at Tcg2ConfigDriverEntryPoint(), but this module is depended on protocol gEfiTcg2ProtocolGuid, if there is no TPM2 present, this module will not run and the variable value keeps last state.
    If I first add TPM2 device, boot once, then remove it and add TPM1.2, I think when it resumes form S3, DetectTpmDevice() function will derictly return TPM2 type, then auto detection seems wrong.
    So I guess we should add a new common module which has no dependence and its work is only to save TPM type from PCD to variable at "ReadyToBoot" event. 
    If any mistake in my understanding, please let me know.
    Thank you.


------------------
BR
winddy_zhang

Re: [EDK2 tcg2] TCG2 variable TCG2_DEVICE_DETECTION_NAME does not work as expected?

[Zhang, Chao B]

Winddy:
  UEFI TCG/TCG2 solution is designed to make one BIOS image workable with either TPM1.2 or TPM2.0.
According to TCG2 spec explanation about TBB/TCB (the platform hardware, connection between CPU, Chipset & TPM etc.)
should always be secure and never be compromised. So here, the TPM chip switch is not a valid case we need to handle.






Thanks & Best regards
Chao Zhang

-----Original Message-----
From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of winddy
Sent: Sunday, October 09, 2016 9:18 PM
To: edk2-devel
Cc: winddy_zhang
Subject: [edk2] [EDK2 tcg2] TCG2 variable TCG2_DEVICE_DETECTION_NAME does not work as expected?

Hi experts, 
    Now I am studying latest tcg2 modules, and I guess there may be something wrong with variable (TCG2_DEVICE_DETECTION_NAME, gTcg2ConfigFormSetGuid). 
    This variable is used to save TPM device type(TPM1.2, TPM2.0, or not present) detected at PEI. The save action is at Tcg2ConfigDriverEntryPoint(), but this module is depended on protocol gEfiTcg2ProtocolGuid, if there is no TPM2 present, this module will not run and the variable value keeps last state.
    If I first add TPM2 device, boot once, then remove it and add TPM1.2, I think when it resumes form S3, DetectTpmDevice() function will derictly return TPM2 type, then auto detection seems wrong.
    So I guess we should add a new common module which has no dependence and its work is only to save TPM type from PCD to variable at "ReadyToBoot" event. 
    If any mistake in my understanding, please let me know.
    Thank you.


------------------
BR
winddy_zhang
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