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CSR Bit Fields

RISC-V mstateen0h CSR Register

Address 0x31CPrivilege MachineAccess RW / RV32-only high half / 32-bitMachine delegation, environment-configuration, and state-enable CSRs

mstateen0h (0x31C) is the RV32 M-mode high-half CSR for bits 63:32 of mstateen0.

Related Search Terms
mstateen0h CSRmstateen0h 0x31CRV32 mstateen0 highmstateen0 SE0Smstateen mstateen0hhstateen0 sstateen0
Bit Overview
bit 3 = only bit 3; bits 12..11 = bits 12 down to 11
MSBLSB
Field Map

Understand mstateen0h By Bit Fields

0 key fields
Official Basis & Search Notes

mstateen0h exists only on RV32 as the access window for mstateen0 bits 63:32. Bit 31 maps mstateen0.SE0, letting M-mode control lower-privilege access to matching hstateen0/sstateen0 CSRs.

mstateen0h is the RV32 high-half alias of mstateen0; RV64 uses 64-bit mstateen0 and has no mstateen0h CSR.
A stateen CSR controls access below its own privilege level, not access by that same level.
SE0 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 mstateen0h to access bits 63:32 of mstateen0; this high-half CSR does not exist on RV64.
  • - Use address 0x31C 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 mstateen0h before initializing lower-privilege environment state to observe the upper 32 bits of mstateen0.

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 mstateen0h exist on RV64?

No. mstateen0h is the RV32 CSR for accessing the upper 32 bits of mstateen0.

Can the low 31 bits of mstateen0h be assigned private meanings?

No. They should be interpreted only as officially defined stateen bits; unimplemented state and undefined reserved bits read as zero.