Re: [PATCH v6 6/6] doc: Add measured boot documentation

[Eddie James <eajames@linux.ibm.com>]

On 2/22/23 14:26, Heinrich Schuchardt wrote:
>
> Am 22. Februar 2023 19:02:42 MEZ schrieb Eddie James <eajames@linux.ibm.com>:
>> Briefly describe the feature and specify the requirements.
>>
>> Signed-off-by: Eddie James <eajames@linux.ibm.com>
>> ---
>> doc/usage/index.rst         |  1 +
>> doc/usage/measured_boot.rst | 23 +++++++++++++++++++++++
>> 2 files changed, 24 insertions(+)
>> create mode 100644 doc/usage/measured_boot.rst
>>
>> diff --git a/doc/usage/index.rst b/doc/usage/index.rst
>> index cde7dcb14a..0cf78cb0e7 100644
>> --- a/doc/usage/index.rst
>> +++ b/doc/usage/index.rst
>> @@ -12,6 +12,7 @@ Use U-Boot
>>     partitions
>>     cmdline
>>     semihosting
>> +   measured_boot
>>
>> Shell commands
>> --------------
>> diff --git a/doc/usage/measured_boot.rst b/doc/usage/measured_boot.rst
>> new file mode 100644
>> index 0000000000..8357b1f480
>> --- /dev/null
>> +++ b/doc/usage/measured_boot.rst
>> @@ -0,0 +1,23 @@
>> +.. SPDX-License-Identifier: GPL-2.0+
>> +
>> +Measured Boot
>> +=====================
> This completely misses o describe measured boot with UEFI.
>
> @Ilias, do you want to add that in a follow up patch?
>
>> +
>> +U-Boot can perform a measured boot, the process of hashing various components
>> +of the boot process, extending the results in the TPM and logging the
>> +component's measurement in memory for the operating system to consume.
>> +
>> +Requirements
>> +---------------------
>> +
>> +* A hardware TPM 2.0 supported by the U-Boot drivers
>> +* CONFIG_TPM=y
>> +* CONFIG_MEASURED_BOOT=y
>> +* Device-tree configuration of the TPM device to specify the memory area
>> +  for event logging. The TPM device node must either contain a phandle to
>> +  a reserved memory region or "linux,sml-base" and "linux,sml-size"
>> +  indicating the address and size of the memory region. An example can be
>> +  found in arch/sandbox/dts/test.dts
>> +* The operating system must also be configured to use the memory regions
>> +  specified in the U-Boot device-tree in order to make use of the event
>> +  log.
> Please, provide enough information such that a reader can set this up. This should include example code.


Hi Heinrich,


I'm not sure what example code you mean. No additional code is necessary 
for U-Boot to perform the measurements, only the requirements stated. If 
you mean the operating system setup, I don't think here is the right 
place to document that, as it has nothing to do with U-Boot. Either way, 
Linux would not require any code, only a similar devicetree entry and 
TPM driver.


Thanks,

Eddie


>
> Best regards
>
> Heinrich