Hi, On Thu, Nov 14, 2024 at 9:37 AM lihuisong (C) <lihuisong@xxxxxxxxxx> wrote: > > Hi Rafael, > > 在 2024/11/13 17:26, Rafael J. Wysocki 写道: > > On Wed, Nov 13, 2024 at 10:07 AM Huisong Li <lihuisong@xxxxxxxxxx> wrote: > >> There are many 'cdevX' files which link cooling devices under > >> '/sys/class/thermal/thermal_zoneX/'. These devices contain active cooling > >> devices and passive cooling devices. And user cann't directly know which > >> devices temperature is represented by the thermal zone. > >> > >> However, ACPI spec provides a '_TZD' object which evaluates to a package > >> of device names. Each name corresponds to a device in the ACPI namespace > >> that is associated with the thermal zone. The temperature reported by the > >> thermal zone is roughly correspondent to that of each of the devices. > >> > >> User can get all devices a thermal zone measured by the 'measures' > >> directory under the thermal zone device. > > Well, that's kind of clear, but what exactly is the use case? Why > > does the user need to know that? > IMO, this makes thermal zone information more friendly. > For instance, user can directly know the temperature of CPUs or other > devices is roughly represented by which thermal zone. > This may offer the convenience for further usersapce application. > > BTW, the '_TZD' method is similar to the '_PMD' in acpi power meter. > Since ACPI spec provides them, they should also have a role in their > existence. So there is no specific use case, but it is possible that somebody may want to use this information, IIUC. Well, let's defer making kernel changes until there is a user wanting/needing this information. Then we'll decide how to expose it. For one, I'm not convinced that exposing it under the ACPI representation of a thermal zone is going to be really useful.
