Re: [PATCH v2] aspeed: Deprecate the tacoma-bmc machine

["Cédric Le Goater" <clg@redhat.com>]

On 8/26/24 20:50, Guenter Roeck wrote:
> Hi,
> 
> On 8/26/24 02:58, Cédric Le Goater wrote:
>> Hello Guenter,
>>
>> On 8/9/24 00:05, Guenter Roeck wrote:
>>> Hi,
>>>
>>> On Tue, Jun 25, 2024 at 09:08:30AM +0200, Cédric Le Goater wrote:
>>>> The tacoma-bmc machine was a board including an AST2600 SoC based BMC
>>>> and a witherspoon like OpenPOWER system. It was used for bring up of
>>>> the AST2600 SoC in labs. It can be easily replaced by the rainier-bmc
>>>> machine which is part of a real product offering.
>>>>
>>>> Signed-off-by: Cédric Le Goater <clg@redhat.com>
>>>
>>> I have been using tacoma-bmc to test tcg,tpm-tis-i2c functionality
>>> on arm. rainier-bmc doesn't support that, and other IBM BMCs which
>>> do support it (bonnell, everest, system1) are not supported in qemu.
>>>
>>> Do you have a suggested alternative ?
>>
>> Could you use the ast2600-evb machine instead ? as done in
>> machine_aspeed.py, see routine test_arm_ast2600_evb_buildroot_tpm.
>>
> 
> Unfortunately, that does not work for me because that requires instantiating
> the tpm chip from the CLI by writing into the new_device sysfs attribute,
> and I can not do that in my test environment.

Ah. too bad.

>> We can't add a "tpm-tis-i2c" device to the tacoma-bmc machine init
>> routine because a TPM backend is required.
>>
> 
> Not sure I understand; tacoma-bmc instantiates the TPM chip through its
> devicetree file which is what I was looking for.

I meant at the "HW" board level in QEMU.

We can not instantiate the TPM I2C chip device model in the tacoma-bmc
machine init routine and attach it to the I2C bus because of the required
TPM backend. This means that the device is necessarily defined on the QEMU
command line and this makes the ast2600-evb and tacoma-bmc machine very
similar in terms of HW definitions.
  
> I solved the problem by adding support for IBM Bonnell (which instantiates
> the TPM chip through its devicetree file, similar to tacoma-bmc) to my local
> copy of qemu. 

Hmm, did you copy the rainier-bmc machine definition ?

> It isn't perfect since I don't know the correct HW pin strapping
> and reused the strapping from Rainier, but it works for me.

Keeping the tacoma-bmc machine is fine if there is a use for it. Testing
the TPM I2C device driver is certainly a good use but we should reflect
that in QEMU also (so that we don't forget). Could we change the test in
machine_aspeed.py to use the tacoma-bmc machine instead ? and revert the
deprecation patch of course.

Thanks,

C.