    /* SPDX-License-Identifier: MIT */
    /******************************************************************************
     * arch-x86_64.h
     *
     * Guest OS interface to x86 64-bit Xen.
     *
     * Copyright (c) 2004-2006, K A Fraser
     */

    #include "arch-x86/xen.h"

    /*
     * ` enum neg_errnoval
     * ` HYPERVISOR_set_callbacks(unsigned long event_selector,
     * `                          unsigned long event_address,
     * `                          unsigned long failsafe_selector,
     * `                          unsigned long failsafe_address);
     * ` [see __HYPERVISOR_set_callbacks]
     * `
     * Register for callbacks on events.  When an event (from an event
     * channel) occurs, event_address is used as the value of eip.
     *
     * A similar callback occurs if the segment selectors are invalid.
     * failsafe_address is used as the value of eip.
     *
     * On x86_64, event_selector and failsafe_selector are ignored (?!?).
     */