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CSR Bit Fields

RISC-V mstateen1h CSR Register

Address 0x31DPrivilege MachineAccess RW / RV32-only high half / 32-bitMachine delegation, environment-configuration, and state-enable CSRs

mstateen1h (0x31D) is the RV32 M-mode high-half CSR for bits 63:32 of mstateen1.

Related Search Terms
mstateen1h CSRmstateen1h 0x31DRV32 mstateen1 highmstateen1 SE1Smstateen mstateen1hhstateen1 sstateen1
Bit Overview
bit 3 = only bit 3; bits 12..11 = bits 12 down to 11
MSBLSB
Field Map

Understand mstateen1h By Bit Fields

0 key fields
Official Basis & Search Notes

mstateen1h exists only on RV32 as the access window for mstateen1 bits 63:32. Bit 31 maps mstateen1.SE1, letting M-mode control lower-privilege access to matching hstateen1/sstateen1 CSRs.

mstateen1h is the RV32 high-half alias of mstateen1; RV64 uses 64-bit mstateen1 and has no mstateen1h CSR.
A stateen CSR controls access below its own privilege level, not access by that same level.
SE1 is WARL and may be read-only zero only under the official conditions.
RISC-V Privileged Architecture Manual v20260120, CSR tableRISC-V Privileged Architecture Manual v20260120, Smstateen/Ssstateen

What To Check First When Reading This CSR

  • - Only RV32 uses mstateen1h to access bits 63:32 of mstateen1; this high-half CSR does not exist on RV64.
  • - Use address 0x31D and the lowest access privilege (Machine) to decide whether software may read it directly.
  • - Do not infer undefined functions from bit positions when reading WARL, RO0, or WPRI fields; interpret them through the matching full CSR and extension rules.

Risk Checks Before Writing

  • - Preserve WPRI bits and unchanged fields when writing; whether each writable bit is actually writable depends on the corresponding extension and implementation.
  • - Read back WARL fields after writes to confirm the value accepted by the implementation.

Put It Back Into A Real Flow

1

On RV32, read mstateen1h before initializing lower-privilege environment state to observe the upper 32 bits of mstateen1.

2

Modify only target fields and preserve all other bits.

3

When needed, read the CSR back and confirm the effect through later lower-privilege accesses, traps, or state updates.

FAQ

Does mstateen1h exist on RV64?

No. mstateen1h is the RV32 CSR for accessing the upper 32 bits of mstateen1.

Can the low 31 bits of mstateen1h be assigned private meanings?

No. In the current manual, these bits are reserved unless a future standard defines a stateen meaning; undefined reserved bits read as zero.