在acpi_ns_get_device_callback 中如果匹配到HID或者CID 后会检查当前节点是否有_STA
_STA 主要用于判断当前设备是否存在
/* Run _STA to determine if device is present */
status = acpi_ut_execute_STA(node, &flags);
if (ACPI_FAILURE(status)) {
return (AE_CTRL_DEPTH);
}
if (!(flags & ACPI_STA_DEVICE_PRESENT) &&
!(flags & ACPI_STA_DEVICE_FUNCTIONING)) {
/*
* Don't examine the children of the device only when the
* device is neither present nor functional. See ACPI spec,
* description of _STA for more information.
*/
return (AE_CTRL_DEPTH);
}
可见如果从bios查询到的_STA的flag ,没有包含ACPI_STA_DEVICE_PRESENT和ACPI_STA_DEVICE_FUNCTIONING的话,acpi_ns_get_device_callback函数就退出了,不会为这个设备建立设备节点.
_STA 主要用于判断当前设备是否存在
最新推荐文章于 2024-11-21 16:41:00 发布