引用:static inline void disable_acpi(void)
{
    acpi_disabled = 1;
    acpi_pci_disabled = 1;
    acpi_noirq = 1;
}

引用:/******************************************************************************
 *
 * FUNCTION:    acpi_hw_set_mode
 *
 * PARAMETERS:  mode            - SYS_MODE_ACPI or SYS_MODE_LEGACY
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Transitions the system into the requested mode.
 *
 ******************************************************************************/
acpi_status acpi_hw_set_mode(u32 mode)
{

    acpi_status status;

    ACPI_FUNCTION_TRACE(hw_set_mode);

    /* If the Hardware Reduced flag is set, machine is always in acpi mode */

    if (acpi_gbl_reduced_hardware) {
        return_ACPI_STATUS(AE_OK);
    }

    /*
     * ACPI 2.0 clarified that if SMI_CMD in FADT is zero,
     * system does not support mode transition.
     */
    if (!acpi_gbl_FADT.smi_command) {
        ACPI_ERROR((AE_INFO,
                "No SMI_CMD in FADT, mode transition failed"));
        return_ACPI_STATUS(AE_NO_HARDWARE_RESPONSE);
    }

    /*
     * ACPI 2.0 clarified the meaning of ACPI_ENABLE and ACPI_DISABLE
     * in FADT: If it is zero, enabling or disabling is not supported.
     * As old systems may have used zero for mode transition,
     * we make sure both the numbers are zero to determine these
     * transitions are not supported.
     */
    if (!acpi_gbl_FADT.acpi_enable && !acpi_gbl_FADT.acpi_disable) {
        ACPI_ERROR((AE_INFO,
                "No ACPI mode transition supported in this system "
                "(enable/disable both zero)"));
        return_ACPI_STATUS(AE_OK);
    }

    switch (mode) {
    case ACPI_SYS_MODE_ACPI:

        /* BIOS should have disabled ALL fixed and GP events */

        status = acpi_hw_write_port(acpi_gbl_FADT.smi_command,
                        (u32) acpi_gbl_FADT.acpi_enable, 8);
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                  "Attempting to enable ACPI mode\n"));
        break;

    case ACPI_SYS_MODE_LEGACY:
        /*
         * BIOS should clear all fixed status bits and restore fixed event
         * enable bits to default
         */
        status = acpi_hw_write_port(acpi_gbl_FADT.smi_command,
                        (u32)acpi_gbl_FADT.acpi_disable, 8);
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                  "Attempting to enable Legacy (non-ACPI) mode\n"));
        break;

    default:

        return_ACPI_STATUS(AE_BAD_PARAMETER);
    }

    if (ACPI_FAILURE(status)) {
        ACPI_EXCEPTION((AE_INFO, status,
                "Could not write ACPI mode change"));
        return_ACPI_STATUS(status);
    }

    return_ACPI_STATUS(AE_OK);
}