Re: [PATCH 1/1] drivers: acpi: add CPU id to cooling device type of processor driver

[Eduardo Valentin <edubezval@gmail.com>]

On Thu, May 05, 2016 at 12:00:57AM +0200, Rafael J. Wysocki wrote:
> On Wednesday, May 04, 2016 02:54:32 PM Srinivas Pandruvada wrote:
> > On Wed, 2016-05-04 at 23:49 +0200, Rafael J. Wysocki wrote:
> > > On Tue, May 3, 2016 at 7:04 AM, Eduardo Valentin <edubezval@gmail.com
> > > > wrote:
> > > > 
> > > > Currently, in an ACPI based system, the processor driver registers
> > > > one cooling device per processor. However, the cooling device type
> > > > is the same for each processor. For example, on a system with four
> > > > processors, the sysfs reading of each cooling device would look
> > > > like:
> > > > ebv@besouro ~ $ cat /sys/class/thermal/cooling_device*/type
> > > > Processor
> > > > Processor
> > > > Processor
> > > > Processor
> > > > 
> > > > which turns out to fine. But, some parts of the thermal code may
> > > > use
> > > > type to identify participating devices in a thermal zone. Besides,
> > > > adding notifications to user space may cause the production of
> > > > messages
> > > > that may confuse the listener.
> > > > 
> > > > For this reason, this patch adds the processor ID cooling device
> > > > type.
> > > > After this change, the cooling device listing in the same previous
> > > > example
> > > > would look like this:
> > > > ebv@besouro ~ $ cat /sys/class/thermal/cooling_device*/type
> > > > Processor.0
> > > > Processor.1
> > > > Processor.2
> > > > Processor.3
> > > > 
> > > > allowing an easier identification of cooling device target.
> > > 
> > > Is it not going to confuse any user space scripts or similar?
> >
> > Yes, it will.
> 
> In that case the patch cannot be applied.

In fact, we shall never brake userspace. 

Srinivas, could you please elaborate a bit more on how this would break
userspace? How different would it be having an extra id? Are you
expecting "Processor" string in daemon?

BR,

> 
> Thanks,
> Rafael
>