* unstable /sys interface from hmon
@ 2017-01-30 20:37 Daniel Walker
2017-01-30 23:11 ` Guenter Roeck
0 siblings, 1 reply; 2+ messages in thread
From: Daniel Walker @ 2017-01-30 20:37 UTC (permalink / raw)
To: xe-kernel, Greg Kroah-Hartman, Jean Delvare, Guenter Roeck,
lm-sensors, linux-kernel
Hi,
Cisco recently upgraded to kernel 4.4.. We have applications which use the /sys interfaces for some hmon drivers.
We found that the following patches,
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=bab2243ce1897865e31ea6d59b0478391f51812b
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c3b7cddc70075d525db6b3068d8b2b9158eedc84
Altered the interface as seen from userspace. These patches changed the paths in the following way,
Before,
/sys/bus/i2c/devices/14-0050/
After,
/sys/bus/i2c/devices/14-0050/hwmon/hwmon7
My impression was that /sys was suppose to be stable, and debugfs was unstable. I'm not sure what the current guidelines are
for this, but we would request that hmon drivers maintain a stable interface from /sys. This change has cause upgrade issues
for us which we would like to avoid in the future.
A patch to add in a compatibility layer would be welcome.
Daniel
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: unstable /sys interface from hmon
2017-01-30 20:37 unstable /sys interface from hmon Daniel Walker
@ 2017-01-30 23:11 ` Guenter Roeck
0 siblings, 0 replies; 2+ messages in thread
From: Guenter Roeck @ 2017-01-30 23:11 UTC (permalink / raw)
To: Daniel Walker
Cc: xe-kernel, Greg Kroah-Hartman, Jean Delvare, lm-sensors, linux-kernel
On Mon, Jan 30, 2017 at 12:37:14PM -0800, Daniel Walker wrote:
> Hi,
>
> Cisco recently upgraded to kernel 4.4.. We have applications which use the /sys interfaces for some hmon drivers.
> We found that the following patches,
>
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=bab2243ce1897865e31ea6d59b0478391f51812b
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c3b7cddc70075d525db6b3068d8b2b9158eedc84
>
> Altered the interface as seen from userspace. These patches changed the paths in the following way,
>
> Before,
> /sys/bus/i2c/devices/14-0050/
>
> After,
> /sys/bus/i2c/devices/14-0050/hwmon/hwmon7
>
Actually, the stable link to use would be /sys/class/hwmon/hwmon7
in both cases, and to check if the name attribute resides in hwmon7
or in hwmon7/device (which is the real change in your case - it moved
from hwmon7/device to hwmon7, ie from the parent device to the hwmon
device).
> My impression was that /sys was suppose to be stable, and debugfs was unstable. I'm not sure what the current guidelines are
> for this, but we would request that hmon drivers maintain a stable interface from /sys. This change has cause upgrade issues
> for us which we would like to avoid in the future.
>
The key transition is the move from attaching the attributes to the parent
device (here: the i2c device) to the hwmon device. libsensors handles this
transition transparently; I assume you are not using it ?
> A patch to add in a compatibility layer would be welcome.
>
A compatibility layer would have to link each attribute back to the parent
device. Interesting idea, actually. I'll check if that is possible.
Thanks,
Guenter
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2017-01-30 23:12 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-01-30 20:37 unstable /sys interface from hmon Daniel Walker
2017-01-30 23:11 ` Guenter Roeck
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).