"Guilherme G. Piccoli" [off-list ref] writes:

Subject: Re: [PATCH 2/3] powerpc/xmon: drop the nobt option from xmon plus minor fixes

In future please use the same version number for all patches of a
series.

ie. This should include a v2, like the rest of the patches in the series.

It confuses the tools to have "v2 1/3" "2/3" "v2 3/3".

I realise that might seem a little odd when a patch is new to the
series, but the version is the version *of the series*, not the
individual patches.

For a new patch you can just add after the change log:

---
v2: New for v2 of the series.


For example.

The xmon parameter nobt was added long time ago, by commit 26c8af5f01df
("[POWERPC] print backtrace when entering xmon"). The problem that time
was that during a crash in a machine with USB keyboard, xmon wouldn't
respond to commands from the keyboard, so printing the backtrace wouldn't
be possible.

Idea then was to show automatically the backtrace on xmon crash for the
first time it's invoked (if it recovers, next time xmon won't show
backtrace automatically). The nobt parameter was added _only_ to prevent
this automatic trace show. Seems long time ago USB keyboards didn't work
that well!

We don't need it anymore, but the feature of auto showing the backtrace
on first crash seems interesting (imagine a case of auto-reboot script),
so this patch keeps the functionality, yet removes the nobt parameter.

I'm going to take this as-is, because I want to get it in for v4.11.

But I don't think we need the auto back trace logic at all. If anything
it's an anti-feature IMHO.

Imagine you're debugging a machine and you drop into xmon to check
something, then drop out again.

Then you go away and leave the box, and it crashes into xmon, but xmon
doesn't print a backtrace because you've already been in xmon. Usually
you can just get on the console and hit 't', but sometimes the machine
crashes so hard that xmon doesn't take input - in which case you now
have no backtrace. :sadface:

So I'll send a follow-up patch to remove the auto backtrace stuff
completely and see if anyone objects.

cheers