Open james-ball-qualcomm opened 4 weeks ago
From my side this extension is affecting all mode supported by the CLIC.
If CLIC is supporting only M mode, then this extension will affect only M registers If CLIC is supporting M and S mode, then this extension will affect M and S mode.
As soon as you get Selective Hardware vectoring supported on M mode, the cost to support it for S is for free. So x prefix is the good one from my side.
Maybe I forget some aspects. We can discuss this tonight.
i think there is no precedent for an x prefix in an extension. the normal thing to do is to have a smclicshv and a ssclicshv. However, here we do not want them to be selectable individually. So if smclicshv and sslic are supported, ssclicshv is mandatory. Otherwise, ssclicshv is forbidden.
Precedent in Priv ISA manual:
Chapter 5. "Smcsrind/Sscsrind" Indirect CSR Access, Version 1.0.0 5.1. Introduction Smcsrind/Sscsrind is an ISA extension that extends the indirect CSR access mechanism originally defined as part of the Smaia/Ssaia extensions, in order to make it available for use by other extensions without creating an unnecessary dependence on Smaia/Ssaia. This extension confers two benefits:
Another:
Chapter 4. "Smstateen/Ssstateen" Extensions, Version 1.0.0
The smclicshv extension naming (i.e. sm*) suggests it only has M-mode features. Does it have S-mode features too? I ask because the smclicshv chapter uses the 'x' prefix notation instead of 'm'. What gives?