diff --git a/body.adoc b/body.adoc index 74d7396..f40f61d 100644 --- a/body.adoc +++ b/body.adoc @@ -239,7 +239,7 @@ allocated. [NOTE] [%unbreakable] ==== -__Ordinarily, each vsireg__i _will access register state, access read-only 0 state, or raise an exception (either an illegal instruction exception or, for select accesses from VS-mode, a virtual instruction exception). When vsiselect holds a value that is implemented at HS level but not at VS level, attempts to access sireg* (really vsireg*) from VS-mode will typically raise a virtual instruction exception._ +__Ordinarily, each vsireg__i _will access register state, access read-only 0 state, or raise an exception (either an illegal instruction exception or, for select accesses from VS-mode, a virtual instruction exception). When vsiselect holds a value that is implemented at HS level but not at VS level, attempts to access sireg* (really vsireg*) from VS-mode will typically raise a virtual instruction exception. But there may be cases specific to an extension where different behavior is more appropriate._ ==== Like siselect and sireg*, the widths of vsiselect and vsireg* are always @@ -269,7 +269,7 @@ VU-mode to directly access vsiselect or vsireg*, and for all attempts from VU-mode to access siselect or sireg*. If the hypervisor extension is implemented, the same bit is defined also -in hypervisor CSR hstateen0, but concerns only siselect and sireg* +in hypervisor CSR hstateen0, but controls access to only siselect and sireg* (really vsiselect and vsireg*), which is the state potentially accessible to a virtual machine executing in VS or VU-mode. When hstateen0[60]=0 and mstateen0[60]=1, all attempts from VS or VU-mode to @@ -281,3 +281,8 @@ Extension Ssstateen is defined as the supervisor-level view of Smstateen. Therefore, the combination of Sscsrind and Ssstateen incorporates the bit defined above for hstateen0 but not that for mstateen0, since machine-level CSRs are not visible to supervisor level. + +[NOTE] +==== +_CSR address space is reserved for a possible future "Sucsrind" extension that extends indirect CSR access to user mode._ +====