FAQ Search Today's Posts Mark Forums Read
» Video Reviews

» Linux Archive

Linux-archive is a website aiming to archive linux email lists and to make them easily accessible for linux users/developers.


» Sponsor

» Partners

» Sponsor

Go Back   Linux Archive > Debian > Debian Development

 
 
LinkBack Thread Tools
 
Old 02-05-2010, 12:47 AM
 
Default why are the watchdog drivers blacklisted?

/etc/modprobe.d/blacklist.conf contains this comment, but why?

# watchdog drivers should be loaded only if a watchdog daemon is installed

I maintain the package providing it, but I fear it is the result of
cargo cult sysadmining.
A driver will not engage the watchdog anyway until /dev/watchdog is
opened.

--
ciao,
Marco
 
Old 02-05-2010, 08:11 AM
Petter Reinholdtsen
 
Default why are the watchdog drivers blacklisted?

[Marco d'Itri]
> I maintain the package providing it, but I fear it is the result of
> cargo cult sysadmining. A driver will not engage the watchdog
> anyway until /dev/watchdog is opened.

If I remember correctly, the reason is that the observed behaviour is
that a driver sometimes will engage the watchdog without /dev/watchdog
is opened, triggered by one driver starting without anyone touching
/dev/watchdog. This caused the installer to stop after 1 minute. I
do not remember any more details. This was discovered a few years
ago, and I hope that crazy driver has been fixed in the mean time.

Happy hacking,
--
Petter Reinholdtsen


--
To UNSUBSCRIBE, email to debian-devel-REQUEST@lists.debian.org
with a subject of "unsubscribe". Trouble? Contact listmaster@lists.debian.org
 
Old 02-05-2010, 10:01 AM
Mark Brown
 
Default why are the watchdog drivers blacklisted?

On Fri, Feb 05, 2010 at 10:11:25AM +0100, Petter Reinholdtsen wrote:
> [Marco d'Itri]

> > I maintain the package providing it, but I fear it is the result of
> > cargo cult sysadmining. A driver will not engage the watchdog
> > anyway until /dev/watchdog is opened.

> If I remember correctly, the reason is that the observed behaviour is
> that a driver sometimes will engage the watchdog without /dev/watchdog
> is opened, triggered by one driver starting without anyone touching
> /dev/watchdog. This caused the installer to stop after 1 minute. I
> do not remember any more details. This was discovered a few years
> ago, and I hope that crazy driver has been fixed in the mean time.

That's just a buggy watchdog driver, though (unless the problem was
really that the watchdog was already enabled by the hardware prior to
startup, but then not loading the driver isn't going to help anything).


--
To UNSUBSCRIBE, email to debian-devel-REQUEST@lists.debian.org
with a subject of "unsubscribe". Trouble? Contact listmaster@lists.debian.org
 
Old 02-05-2010, 10:43 AM
Frans Pop
 
Default why are the watchdog drivers blacklisted?

Petter Reinholdtsen wrote:
> This caused the installer to stop after 1 minute.

Not sure how this could have affected the installer as we don't include any
watchdog modules in D-I (at least, not that I'm aware of).

Cheers,
FJP


--
To UNSUBSCRIBE, email to debian-devel-REQUEST@lists.debian.org
with a subject of "unsubscribe". Trouble? Contact listmaster@lists.debian.org
 
Old 02-05-2010, 01:08 PM
 
Default why are the watchdog drivers blacklisted?

On Feb 05, Petter Reinholdtsen <pere@hungry.com> wrote:

> do not remember any more details. This was discovered a few years
> ago, and I hope that crazy driver has been fixed in the mean time.
So it looks like this *is* my fault, in my defense I can only say that I
got bad advice from the kernel maintainers...
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=249600

I cannot even find anymore this i810_tco/i8xx_tco module, so in the next
udev upload I will remove all watchdog drivers from the blacklist and
maybe add back the ones reported as broken.

--
ciao,
Marco
 
Old 02-06-2010, 03:29 PM
Henrique de Moraes Holschuh
 
Default why are the watchdog drivers blacklisted?

On Fri, 05 Feb 2010, Marco d'Itri wrote:
> On Feb 05, Petter Reinholdtsen <pere@hungry.com> wrote:
> > do not remember any more details. This was discovered a few years
> > ago, and I hope that crazy driver has been fixed in the mean time.
> So it looks like this *is* my fault, in my defense I can only say that I
> got bad advice from the kernel maintainers...
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=249600
>
> I cannot even find anymore this i810_tco/i8xx_tco module, so in the next
> udev upload I will remove all watchdog drivers from the blacklist and
> maybe add back the ones reported as broken.

It got renamed to wdt_tco, I think, and it will hard-hang a lot of thinkpads
if it ever triggers, for example: the SMBIOS can't handle it.

Anyway, if for any reason we load a watchdog driver, AND any of the watchdog
userspace packages by mistake, we can cause data loss.

For example: someone decided that once every 10s was a good default watchdog
pat, which is incorrect. If the platform or the kernel driver defaults to
10s or less, bad things happen. I have seen this happen on Lenny.

I.e. even if the kernel and platform cooperates, we don't have done our work
carefully enough yet to risk these things getting enabled without local
setup.

--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh


--
To UNSUBSCRIBE, email to debian-devel-REQUEST@lists.debian.org
with a subject of "unsubscribe". Trouble? Contact listmaster@lists.debian.org
 
Old 02-06-2010, 04:23 PM
 
Default why are the watchdog drivers blacklisted?

On Feb 06, Henrique de Moraes Holschuh <hmh@debian.org> wrote:

> It got renamed to wdt_tco, I think, and it will hard-hang a lot of thinkpads
> if it ever triggers, for example: the SMBIOS can't handle it.
OK, I will blacklist this one.

> Anyway, if for any reason we load a watchdog driver, AND any of the watchdog
> userspace packages by mistake, we can cause data loss.
root can cause data loss by running rm -rf / by mistake as well, so this
is not a great argument.

--
ciao,
Marco
 
Old 02-06-2010, 10:08 PM
Darren Salt
 
Default why are the watchdog drivers blacklisted?

I demand that Marco d'Itri may or may not have written...

> On Feb 06, Henrique de Moraes Holschuh <hmh@debian.org> wrote:
>> It got renamed to wdt_tco, I think,

Do you mean iTCO_wdt? If so, then you should know that that's working fine on
my EeePC 901.

>> and it will hard-hang a lot of thinkpads if it ever triggers, for
>> example: the SMBIOS can't handle it.

> OK, I will blacklist this one.

Via /etc/modprobe.d/*? It looks more like a case for DMI-based blacklisting
to me. However, according to the module source, this can be used for
computers with broken BIOSes (given CONFIG_ITCO_VENDOR_SUPPORT=y):

options iTCO_wdt vendorsupport=901

[snip]
--
| Darren Salt | linux at youmustbejoking | nr. Ashington, | Doon
| using Debian GNU/Linux | or ds ,demon,co,uk | Northumberland | Army
| + This comment has been censored.

I'd like to, but my mother would never let me hear the end of it.


--
To UNSUBSCRIBE, email to debian-devel-REQUEST@lists.debian.org
with a subject of "unsubscribe". Trouble? Contact listmaster@lists.debian.org
 
Old 02-07-2010, 11:32 AM
Henrique de Moraes Holschuh
 
Default why are the watchdog drivers blacklisted?

On Sat, 06 Feb 2010, Marco d'Itri wrote:
> On Feb 06, Henrique de Moraes Holschuh <hmh@debian.org> wrote:
> > It got renamed to wdt_tco, I think, and it will hard-hang a lot of thinkpads
> > if it ever triggers, for example: the SMBIOS can't handle it.
> OK, I will blacklist this one.

I'd rather we had a watchdog mini policy that boils down to:

Watchdog drivers have to default to *at least* N seconds timeout (N can't be
too large, some watchdogs have hardware/firmware limits).

All watchdog-enabled packages have to default to *at most* N/2 seconds
timeout (probably N/3 is better, though).

The blacklisting of watchdog drivers would be switched to default options to
ensure the "N seconds timeout", or alternatively, we would need to fix it on
the kernel tree. I prefer the options, because AFAIK some kernel drivers
default to "leave the timeout to whatever was set by the BIOS", and it would
be tough to get that policy changed upstream.

> > Anyway, if for any reason we load a watchdog driver, AND any of the watchdog
> > userspace packages by mistake, we can cause data loss.
> root can cause data loss by running rm -rf / by mistake as well, so this
> is not a great argument.

And if that happens because of any default config or package maintainer
script, it is a "critical" bug. At least the watchdog issues would warrant
at most "grave" bugs (and personally I would place them at severity
"important", since spurious reboots are a normal and expected failure mode
of a watchdog system).

--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh


--
To UNSUBSCRIBE, email to debian-devel-REQUEST@lists.debian.org
with a subject of "unsubscribe". Trouble? Contact listmaster@lists.debian.org
 
Old 02-08-2010, 02:45 AM
 
Default why are the watchdog drivers blacklisted?

On Feb 07, Henrique de Moraes Holschuh <hmh@debian.org> wrote:

> I'd rather we had a watchdog mini policy that boils down to:
As the udev and module-init-tools maintainer my goal is to support
automatically loading all the drivers which their maintainers intended
to be automatically loaded and blacklist until they are fixed the ones
which are currently too buggy to be automatically loaded.

If the defaults for some drivers are wrong then I can't see why they
should not be fixed, but if default configuration parameters are needed
then they should be provided by the watchdog package.

(BTW, is there any other watchdog daemon? The watchdog package reliably
fails to detect when the system is half-killed by OOM.)

--
ciao,
Marco
 

Thread Tools




All times are GMT. The time now is 04:14 AM.

VBulletin, Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Relevant URLs by vBSEO ©2007, Crawlability, Inc.
Copyright 2007 - 2008, www.linux-archive.org