On 10/7/18 10:49 PM, Linus Walleij wrote:
S.M.A.R.T. temperature sensors have been supported for
years by userspace tools such as smarttools. This adds
support to read it from the kernel and adds a temperature
zone for the drive.
The temperature readout is however also a good fit for
Linux' hwmon subsystem. By adding a hwmon interface to dig
out SMART parameters, we can expose the drive temperature
as a standard hwmon sensor.
The idea came about when experimenting with NAS enclosures
that lack their own on-board sensors but instead piggy-back
the sensor found in the harddrive, if any, to decide on a
policy for driving the on-board fan.
The kernel thermal subsystem supports defining a thermal
policy for the enclosure using the device tree, see e.g.:
arch/arm/boot/dts/gemini-dlink-dns-313.dts
but this requires a proper hwmon sensor integrated with
the kernel.
With this driver, the hard disk temperatur can be read from
sysfs:
> cd /sys/class/hwmon/hwmon0/
> cat temp1_input
38
If the harddrive supports one of the detected vendor
extensions for providing min/max temperatures we also
provide attributes for displaying that.
This means that they can also be handled by userspace
tools such as lm_sensors in a uniform way without need
for any special tools such as "hddtemp" (which seems
dormant).
This driver does not block any simultaneous use of
other SMART userspace tools, it's a both/and approach,
not either/or.
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx> # HWMON
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
---
Hmm. I might be getting something wrong here, but the main problem with
SMART values is that they are _not_ really standardized; plus any drive
is free to implement whatever they want.
Plus there are tons of SMART attribute values, and decoding just one
seems to be a bit poor. At the same time having them in the kernel will
just require us to implement lots of decoding, which I really would
leave to userland.
So overall I'm not sure if that the right approach.
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@xxxxxxx +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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