Subject: Watchdog timers

From: "Teixeira, Joe" <[email-masked]>
Date: Wed, 14 Jun 2000 14:19:52 -0400

Hi,
Does anyone here know if Linux has any watchdog capabilities.  And if so how
are they implemented?  If not does anyone have any ideas of way to implement
watchdog timers?

thanks

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From: Russell King - ARM Linux Admin <[email-masked]>
Date: Wed, 14 Jun 2000 20:01:48 +0100 (BST)

> are they implemented?  If not does anyone have any ideas of way to implement

Yes it does.  Check the kernel configuration scripts.  It supports about 8
PC cards and one kernel software-based watchdog.
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  |   |        Russell King       [email-masked]      --- ---
  | | | |            http://www.arm.linux.org.uk/            /  /  |
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  /   |               THE developer of ARM Linux              |+| /|\
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From: Alex Holden <[email-masked]>
Date: Wed, 14 Jun 2000 23:45:33 +0100 (GMT)

> PC cards and one kernel software-based watchdog.

There is also support for the watchdog timer built into the 21285 
footbridge, and the W83977AF chip used in the NetWinder.

Note that the watchdog timer drivers need a user space daemon which opens 
/dev/watchdog and writes to it on a regular basis (so if the system
crashes, the daemon will stop writing to the device and the watchdog will
time out and reset). There are several of these available; I think you can
find one on ftp.netwinder.org somewhere.

--------------- Linux- the choice of a GNU generation. --------------
: Alex Holden (M1CJD)- Caver, Programmer, Land Rover nut, Radio Ham :

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From: Philip Blundell <[email-masked]>
Date: Wed, 14 Jun 2000 19:56:49 +0100

>are they implemented?  If not does anyone have any ideas of way to implement

On which platforms?  Linux has drivers for a handful of watchdog cards, 
including those built in to the 21285 (ie EBSA-285 etc) and the NetWinder. 
There's also a `softdog' which will sometimes get you unstuck but obviously 
isn't as good as a real watchdog.

p.

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From: Paul Koning <[email-masked]>
Date: Thu, 15 Jun 2000 09:25:35 -0400 (EDT)

>>>>> "Alex" == Alex Holden <[email-masked]> writes:

 Alex> On Wed, 14 Jun 2000, Russell King - ARM Linux Admin wrote:
 >> Yes it does.  Check the kernel configuration scripts.  It supports
 >> about 8 PC cards and one kernel software-based watchdog.

 Alex> There is also support for the watchdog timer built into the
 Alex> 21285 footbridge,

Unfortunately the watchdog timer in the 21285 is deficient -- it works
only in standalone mode.  If you configure the card as a coprocessor
card, the *only* way to issue a reset to it is to do a PCI reset.  An
amazingly dumb mistake to make, but it was made...

     paul