Removed Ssptwad as spec is not complete, but will be added as support…

…ed option in RVA23.

Added Ssptead as name of option with software PT updates.
Closes #57.

profiles.adoc

@@ -688,6 +688,9 @@ NOTE: This is a new extension name.
 
 - *Sv39* Page-Based 39-bit Virtual-Memory System.
 
+- *Ssptead* Page-fault exceptions are raised when a page is accessed
+   when A bit is clear, or written when D bit is clear.
+
 - *Ssccptr* Main memory regions with both the cacheability and
    coherence PMAs must support hardware page-table reads.
 
@@ -753,13 +756,6 @@ used by rich operating systems.
 
 There are no incompatible unprivileged extensions.
 
-The following are incompatible privileged extensions:
-
-- *Ssptwad*  Hardware writes to A and D bits of page table entries.
-
-NOTE: This is incompatible as it requires a pervasive change to
-supervisor-level software when hardware can write A and D bits.
-
 == RVA22 Profiles
 
 The RVA22 profiles are intended to be used for 64-bit application
@@ -1012,6 +1008,9 @@ The following privileged extensions are mandatory:
 
 - *Sv39* Page-Based 39-bit Virtual-Memory System.
 
+- *Ssptead* Page-fault exceptions are raised when a page is accessed
+   when A bit is clear, or written when D bit is clear.
+
 - *Ssccptr* Main memory regions with both the cacheability and
    coherence PMAs must support hardware page-table reads.
 
@@ -1129,13 +1128,6 @@ Incompatible unprivileged extensions are:
 
 - All RVA22U64 incompatible extensions
 
-The following are incompatible privileged extensions:
-
-- *Ssptwad*  Hardware writes to A and D bits of page table entries.
-
-NOTE: This is incompatible as it requires a pervasive change to
-supervisor-level software when hardware can write A and D bits.
-
 ==== RVA22S64 Recommendations
 
 - Implementations are strongly recommended to raise illegal-instruction