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Tweaks to RVB23 profiles #138

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merged 4 commits into from
Jan 12, 2024
Merged

Tweaks to RVB23 profiles #138

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ed8ca10
RVB23U64: delineate extensions added since RVA22U64
aswaterman Dec 22, 2023
e0cbc88
RVB23: mandate Zimop/Zcmop
aswaterman Dec 22, 2023
f11954b
RVB23: move and improve NOTEs
aswaterman Dec 22, 2023
707ff08
RVB23: Ssnpm is optional
aswaterman Dec 22, 2023
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20 changes: 13 additions & 7 deletions rvb23-profile.adoc
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Original file line number Diff line number Diff line change
Expand Up @@ -122,10 +122,15 @@ address space.
- *Zicbom* Cache-Block Management Operations.
- *Zicbop* Cache-Block Prefetch Operations.
- *Zicboz* Cache-Block Zero Operations.
- *Zkt* Data-independent execution time.

The following mandatory extensions are also present in RVA23U64:

- *Zihintntl* Non-temporal locality hints.
- *Zicond* Conditional Zeroing instructions.
- *Zimop* Maybe Operations.
- *Zcmop* Compressed Maybe Operations.
- *Zcb* Additional 16b compressed instructions.
- *Zkt* Data-independent execution time.
- *Zfa* Additional scalar FP instructions.
- *Zawrs* Wait on reservation set.

Expand Down Expand Up @@ -215,6 +220,9 @@ NOTE: Ss1p13 supersedes Ss1p12 but is not yet ratified.

- *Svnapot* NAPOT Translation Contiguity

NOTE: Svnapot is very low cost to provide, so is made mandatory even
in RVB.

The following privileged extensions were also mandatory in RVA22S64:

- *Svbare* The `satp` mode Bare must be supported.
Expand Down Expand Up @@ -248,12 +256,10 @@ The following privileged extensions were also mandatory in RVA22S64:
- *Ssu64xl* `sstatus.UXL` must be capable of holding the value 2
(i.e., UXLEN=64 must be supported).


NOTE: Svnapot is very low cost to provide, so is made mandatory even
in RVB.

- *Sstc* supervisor-mode timer interrupts.

NOTE: Sstc was optional in RVA22.

==== RVB23S64 Optional Extensions

RVB23S64 has the same unprivileged options as RVB23U64,
Expand All @@ -271,6 +277,8 @@ The privileged optional extensions are:

- *Sscofpmf* Count Overflow and Mode-Based Filtering.

- *Ssnpm* Pointer masking.

- *Zkr* Entropy CSR.

The following hypervisor extension and mandates were also in RVA22S64:
Expand Down Expand Up @@ -300,8 +308,6 @@ When the hypervisor extension is implemented, the following are also mandatory:
`satp`, the corresponding hgatp SvNNx4 mode must be supported. The
`hgatp` mode Bare must also be supported.

- *Ssnpm* Pointer masking.

==== RVB23S64 Recommendations

- Implementations are strongly recommended to raise illegal-instruction
Expand Down