is it accurate to describe /dev/watchdog as "legacy"?

Robert P. J. Day rpjday at crashcourse.ca
Sat Oct 15 10:00:08 EDT 2016


  poking around the watchdog code, and in
drivers/watchdog/watchdog_dev.c, i see the snippet:

/*
 *      watchdog_cdev_register: register watchdog character device
 *      @wdd: watchdog device
 *      @devno: character device number
 *
 *      Register a watchdog character device including handling the legacy
                                                                    ^^^^^^
 *      /dev/watchdog node. /dev/watchdog is actually a miscdevice and
 *      thus we set it up like that.
 */

  now, my normal understanding of the word "legacy" is of something
that, while it may still function (possibly because of the need for
backward compatibility), it typically refers to something that is,
strictly speaking, *unnecessary*. that is, while one could continue to
interact with the watchdog through the ostensibly "legacy"
/dev/watchdog special file, there is a newer mechanism that makes it
superfluous.

  in this case, i can see the sysfs structure that you can now select
for working with the watchdog; however, in that same file, it
*appears* that almost all of that sysfs structure is for *querying*
watchdog information, not for making changes to it.

  IOW, as i read it (and i could be wrong), while one could extend the
standard watchdog API with sysfs structure, it is still *necessary* to
continue using /dev/watchdog for some things.

  am i reading this correctly? because if i am, then the word "legacy"
should not really apply to /dev/watchdog, should it?

rday

-- 

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Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
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