linux-kernel - Re: watchdog: iTCO_wdt: cannot register miscdev on minor=130 (err=-16).

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Message-ID: <20200526135421.GB51584@roeck-us.net>
Date:   Tue, 26 May 2020 06:54:21 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Paul Menzel <pmenzel@...gen.mpg.de>
Cc:     Wim Van Sebroeck <wim@...ux-watchdog.org>,
        linux-watchdog@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        it+linux-watchdog@...gen.mpg.de
Subject: Re: watchdog: iTCO_wdt: cannot register miscdev on minor=130
 (err=-16).

Hi Paul,

On Tue, May 26, 2020 at 01:54:40PM +0200, Paul Menzel wrote:
[ ... ]

> 
> I wonder if the error message could be made extended.
> 
Question is what to extend it to. Best we could do would be to report that
the driver will still try to install itself. Since the legacy driver doesn't
use the watchdog infrastructure, the watchdog infrastructure knows nothing
about it, and it can only guess the reason why /dev/watchdog is not
available.

Personally I'd rather see the ipmi watchdog driver to be converted to use
the watchdog subsystem, but that is a bit unlikely to happen.

> > made the default.
> 
> > You might have some other log messages indicating which other watchdog
> > is installed. Otherwise you might need to use ioctls on /dev/watchdog
> > to determine its name. 'lsmod' might also be useful.
> 
> Please find the logs and lsmod output attached. It might be created by the
> IPMI driver.
> 
> ```
> handsomejack:~$ dmesg | grep IPMI
> [    9.890808] IPMI message handler: version 39.2
> [    9.900456] ipmi_si: IPMI System Interface driver
> [   10.080438] ipmi_si dmi-ipmi-si.0: IPMI message handler: Found new BMC
> (man_id: 0x0002a2, prod_id: 0x0100, dev_id: 0x20)
> [   10.113076] ipmi_si dmi-ipmi-si.0: IPMI kcs interface initialized
> [   10.121572] IPMI Watchdog: driver initialized

Yes, that is indeed the case. If you don't want it, you could maybe
blacklist it. Unfortunately it looks like it is built into the kernel,
so you would also have to change your kernel configuration to
CONFIG_IPMI_WATCHDOG=m. Alternatively, you could keep it and just use
/dev/watchdog1. Either case, you should make make sure that it works.

Guenter