Re: [PATCH v4 1/5] acpi: Convert build_tpm2() to build_append* API

[Auger Eric <eric.auger@redhat.com>]

Hi Igor,

On 6/22/20 11:39 AM, Igor Mammedov wrote:
> On Fri, 19 Jun 2020 07:19:51 -0400
> Stefan Berger <stefanb@linux.ibm.com> wrote:
> 
>> On 6/19/20 5:43 AM, Auger Eric wrote:
>>> Hi Laszlo,
>>>
>>> On 6/19/20 11:38 AM, Laszlo Ersek wrote:  
>>>> On 06/18/20 09:50, Auger Eric wrote:  
>>>>> Hi Stefan, Igor,
>>>>>
>>>>> On 6/16/20 4:11 PM, Stefan Berger wrote:  
>>>>>> On 6/16/20 8:33 AM, Igor Mammedov wrote:  
>>>>>>> nevertheless looks like faithfull conversion,
>>>>>>> btw why you didn't drop Acpi20TPM2 structure definition?
>>>>>>>  
>>>>>> If we get rid of the table we should keep a reference to this document,
>>>>>> table 7: "TCG ACPI Specification; Family 1.2 and 2.0; Level 00 Revision
>>>>>> 00.37, December 19, 2014"
>>>>>>
>>>>>> https://trustedcomputinggroup.org/wp-content/uploads/TCG_ACPIGeneralSpecification_1-10_0-37-Published.pdf
>>>>>>
>>>>>>
>>>>>>  
>>>>> Further looking at this spec, the log_area_minimum_length and
>>>>> log_area_start_address only are described in
>>>>> - Table 2 (TCG Hardware InterfaceDescription Table Format for TPM 1.2
>>>>> Clients)
>>>>> - Table 4 (TCG Hardware Interface Description Table Format for TPM 1.2
>>>>> Servers)
>>>>> but not in Table 7, ie. not for TPM 2.0.
>>>>>
>>>>> Are they really needed for TPM2 or what do I miss?  
>>>> (side comment:
>>>>
>>>> LASA and LAML are optional with TPM-2.0. From the discussion at
>>>> <https://bugzilla.tianocore.org/show_bug.cgi?id=978>.  
>>
>>
>> They are needed for (x86) BIOS, such as SeaBIOS, not for UEFI, though. I 
>> do not know about ARM.
>>
>>
>>> Thank you for the pointer and info. I failed to find this info in the
>>> spec. Given the risk of confusion, I would personally keep struct
>>> Acpi20TPM2 and maybe add a comment. Stefan?  
>>
>> Either way is fine with me for as long as we know where to find the 
>> layout of the structure.
> I'd remove Acpi20TPM2 as it hardly documents anything, and add a comment
> pointing to the concrete spec that has these fields.
> 
> TCGTCG ACPI SpecificationFamily “1.2” and “2.0”Version 1.2,Revision 8

[PATCH v6 0/3] vTPM/aarch64 ACPI support was posted.

As documented in the cover letter (history log), the presence of the
LAML and LASA fields in the TPM2 table is not clearly documented in the
spec (at least I failed to find it). It is for TPM 1.2. On the other
hand, Stefan said it is mandated for some x86 BIOS to work. Given this
weirdness I think keeping the  Acpi20TPM2 struct is not too bad. See v6 ...

Thanks

Eric
> 
>>
>>    Stefan
>>
>>>
>>> Thanks
>>>
>>> Eric  
>>>> )
>>>>
>>>> Thanks
>>>> Laszlo
>>>>  
>>
> 
>