On Tue, 2020-06-16 at 09:54 -0400, Jonathan Behrens wrote:
Hi everyone,
To start off discussion about requirements that should go into the platform spec, I propose a simple change to current software:
When entering S-mode for the first time, the a2 register should contain the value 0x54414c5058494e55 ("UNIXPLAT").
The intention here is that software should be able to look for this value and know that it has been booted in a Supervisor Execution Environment that is compliant with the Unix-class platform spec. This would distinguish both from old implementations that only support SBI v0.1, but also possible future execution environments designed by other groups.
For SBI version, supervisor systems should use "sbi_get_spec_version" API to identify what is the SBI version of the SBI implementation. For v0.1, the above call will return a -ve value indicating that this is a v0.1.
That's how linux kernel currently detects the SBI version dynamically.
