# hv_vcpu_set_trap_debug_reg_accesses(_:_:) Sets whether debug-register accesses exit the guest. ``` func hv_vcpu_set_trap_debug_reg_accesses(_ vcpu: hv_vcpu_t, _ value: Bool) -> hv_return_t ``` ## Parameters `vcpu` The instance of the vCPU. `value` A Boolean value that if `true` indicates debug-register accesses in the guest trap to the host. ## Return Value [`HV_SUCCESS`](/documentation/Hypervisor/HV_SUCCESS) if the operation was successful, otherwise an error code specified in [`hv_return_t`](/documentation/Hypervisor/hv_return_t). ## Discussion The trapped registers includes `DBGBCR_EL1`, `DBGBVR_EL1`, `DBGWCR_EL1`, `DBGWVR_EL1.` and `MDSCR_EL1`. The equivalent system register is `MDCR_EL2.TDA`. > Important: > This function must be called by the owning thread. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)