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Message-ID: <9a8748490608121239v63ea829eqc490ac8744677f93@mail.gmail.com>
Date: Sat, 12 Aug 2006 21:39:22 +0200
From: "Jesper Juhl" <jesper.juhl@gmail.com>
To: "Jesse Brandeburg" <jesse.brandeburg@gmail.com>
Subject: Re: RFC : remote driver debugging efforts
Cc: "Om N." <xhandle@gmail.com>, linux-kernel@vger.kernel.org
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On 12/08/06, Jesper Juhl <jesper.juhl@gmail.com> wrote:
> On 12/08/06, Jesse Brandeburg <jesse.brandeburg@gmail.com> wrote:
> > On 8/10/06, Om N. <xhandle@gmail.com> wrote:
> > > (I do not have a remote power on/off switch. The driver panics so
> > > often that somebody has to babysit the machine to switch it off and
> > > on. We are in different time zones and things are not moving forward at all)
> >
> > two (or three) things I've done to help this, when I'm working remotely
> >
> > add panic=30 to your kernel options in grub (or echo 30 >
> > /proc/sys/kernel/panic) to reboot the system automatically on panic.
> >
> > set grub to automatically boot the safe kernel by default, and when
> > making a new kernel, set grub to boot it only once with (say your
> > default is 0 and the new kernel is 1 in grub)
> >
> > echo 'savedefault --default=1 --once' | grub --batch
> >
> > set up netconsole so that you can see the kernel messages (optional) on oops.
> >
> > finding out about all these was incredibly hard and obtuse :-)  So
> > hope this helps.
>
> If you have remote access to the keyboard/display etc, for example via
> a network enabled KVM switch or similar, then magic sysrq can also be
> very helpful to remotely sync & unmount filesystems, and do emergency
> reboots... It can also be used to get stack dumps etc...  Read
> Documentation/sysrq.txt for all the details.
>
> I'm not sure, but I think there was a patch floating around at one
> point that would let you trigger sysrq remotely over the network
> without even logging into the box or having remote keyboard access -
> could be very useful in your case although it is ofcourse extremely
> insecure.
>
One other thing, putting a watchdog card in the box to automatically
reboot it if the machine hangs would also be a good thing. If you
don't have (or don't want to buy) such a card, then building the
kernel with the software watchdog is better than nothing - there are
situations where it'll fail to reboot the machine that a real watchdog
card would be able to handle, but it's a lot better than nothing.
See;  Device Drivers --> Character devices --> Watchdog Cards in menuconfig.

-- 
Jesper Juhl <jesper.juhl@gmail.com>
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