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| author | Andrew Waterman <andrew@sifive.com> | 2018-12-27 10:12:28 -0600 |
|---|---|---|
| committer | Andrew Waterman <andrew@sifive.com> | 2018-12-27 10:12:43 -0600 |
| commit | c6741cb17e51822910dfcf8cb2d21938b9dbc28e (patch) | |
| tree | d69dc20ffa63237d697a079b4ecef39919ae535e | |
| parent | a8b64f5fe8d1cdd715c10585fe289d571473473e (diff) | |
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Clarify that writing pmpcfg does not alter pmpaddr's underlying value
Closes #320.
| -rw-r--r-- | src/machine.tex | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/src/machine.tex b/src/machine.tex index 7f6abaf..41847f5 100644 --- a/src/machine.tex +++ b/src/machine.tex @@ -3006,6 +3006,10 @@ the mode is NAPOT, then bits ${\tt pmpaddr}_i$[G-2:0] read as all ones. When $G \geq 1$ and ${\tt pmpcfg}_i$.A[1] is clear, i.e. the mode is OFF or TOR, then bits ${\tt pmpaddr}_i$[G-1:0] read as all zeros. Bits ${\tt pmpaddr}_i$[G-1:0] do not affect the TOR address-matching logic. +Although changing ${\tt pmpcfg}_i$.A[1] affects the value read from +${\tt pmpaddr}_i$, it does not affect the underlying value stored in that +register---in particular, ${\tt pmpaddr}_i$[G-1] retains its original value +when ${\tt pmpcfg}_i$.A is changed from NAPOT to TOR/OFF then back to NAPOT. \begin{commentary} Software may determine the PMP granularity by writing zero to {\tt pmp0cfg}, |