F20 System Wide Change: Enable kdump on secureboot machines

[Vivek Goyal]

On Thu, Jul 11, 2013 at 12:42:16PM -0600, Stephen John Smoogen wrote:

[..]
> > > Issues I ran into was:
> > >
> > > 1) kdump needs to write to an unencrypted disk space. I tried a USB disk
> > > and various other places but the best ability I got was reinstalling the
> > > laptop and making a /var/crash partition.
> >
> > Is your root encrypted? USB should have worked. Otherwise try dumping
> > to NFS partition. Or ssh the dump out to a different machine. All of
> > these should work.
> >
> >
> The USB was the ones I tried but couldn't get to work correctly.  NFS and
> SSH were not going to work because the problem is with RHEL-5 talking over
> the bridge and my laptop has wireless.

[ I am ccing devel list again. So that if people have ideas about how
  to get serial console on laptop, that will help ]

What do you mean by "NFS and SSH were not going to work because the problem
is with RHEL-5 talking over the bridge"?

I have never tested kdump with wireless. As I always tried to make these
work on servers and always assumed etherhnet connectivity is there.

Anyway, USB case is interesting. I have to admin I have never tried
dumping to USB disk either. But in theory it should work.

Right now it does not work with encrypted disks. Given the fact that
dumping to root disk is easiest on a laptop, I think it is reasonable
to try to make it work with encrypted disks. 

With encrypted disks we don't know where to get the password. I think 
we probably can just wait for user to enter the password. But wait,
we have plenty of issues with display reset in kdump environment. Kdump
might be working in the background while display might be frozen or
garbage displayed. That's why I always use serial console for any kind
of debugging.

So until and unless we figure a way out to solve resetting display issues,
we can't expect a user to enter password on prompt and supporting
encrypted disk is hard. 

Anyway, so as you said in your case trying to mount an un-encrypted
disk/partition and trying to dump to that parition is easiest.

> 
> 
> > > 2) kdump didn't seem to dump for anything than the forced dump in the
> > > instruction manual.
> >
> > You mean dump did not trigger after panic or it did not complete after
> > panic?
> >
> > If kdump kernel is loaded, and panic happens or oops happens and
> > panic_on_oops is set, we should transition in to second kernel and capture
> > dump.
> >
> >
> This did not happen. The system froze completely.

We need to have serial console to debug things here. Without console we
have no idea where things might have gone wrong.

> Power cycle was required
> and nothing was in /var/crash. This could be a problem with my setup but it
> was pretty much stock what the fedora web pages said to do. The
> system-config-kdump application didn't work when I tried it so I went to
> fedora-kernel and got the "we don't expect it to work, please try a rawhide
> kernel and see if it ooops" which it did.
> 
> 
> If it did not work, there must have been some kernel issue. Please open
> > bugs for these issues.
> >
> >
> OK what are you wanting to look for in a bug. At the moment I would just be
> opening the unhelpful bug of:
> 
> laptop freezes. no kdump is found.

We will need a serial console to debug kdump issues. I am not expert
enough to figure out how to reset graphical console without going
through the bios. Is there any reliable way to do that.

Once we have console going then we can try different things like
enabling debugging messages in purgatory, enable early printk etc
to figure out where did things fail.

Now laptops don't have serial port (most new one). Are there any
usb based gadgets which can help here? I don't know.

> 
> Which could be a setup issue on my part or a bunch of other stuff. Since
> the bug is still possible to trigger with Fedora 19+RHEL-5 guest, I can go
> through the steps again to see what needs to be done. I just need to know
> what they are.

So you are running RHEL-5 as Guest with F19 host and trying to take
dump of host?

I think we need to solve the issue of how to get a serial console working
on a laptop to debug this issue.

Anybody, any ideas?

Thanks
Vivek