This content has not been validated; it was AI-generated following the x86-64 ISA Documentation generation process to maintain high quality. However, as no human has verified this data, errors may exist. If the accuracy of this data is critical, please consult the Intel SDM. The model used to generate this is gemma4:31b

VERR

Reads a byte from the specified memory location and verifies that the read operation does not cause a fault or exception. If the read is successful, the ZF flag is cleared; if the read causes a fault or exception, the ZF flag is set and the exception is suppressed.

The table below covers what the source and destinations can be.

DO NOT support LOCK

VERR is not supported in 64-bit mode. It is only available in compatibility mode.

The instruction modifies the ZF flag based on the success of the memory access. It does not modify any general-purpose registers.

To avoid unexpected behavior in 64-bit native code, ensure that VERR is not used, as it will trigger an invalid opcode exception (#UD). When using VERR in compatibility mode, be aware that it only checks for read permissions and does not guarantee that subsequent write operations to the same address will succeed.