Re: [PATCH v3 4/4] printk/nmi: Increase the size of NMI buffer and make it configurable

[Petr Mladek]

On Thu 2015-12-17 14:38:58, Andrew Morton wrote:
> On Tue, 15 Dec 2015 15:26:21 +0100 Petr Mladek <pmladek@xxxxxxxx> wrote:
> 
> > > OK, thanks.  So "not needed at present, might be needed in the future,
> > > useful for out-of-tree debug code"?
> > 
> > It is possible that I got it a wrong way on arm. The NMI buffer is
> > usable there on two locations.
> > 
> > First, the temporary is currently used to handle IPI_CPU_BACKTRACE.
> > It seems that it is not a real NMI. But it seems to be available
> > (compiled) on all arm system. This is why I introduced NEED_PRINTK_NMI
> > Kconfig flag to avoid confusion with a real NMI.
> > 
> > Second, there is the FIQ "NMI" handler that is called from
> > /arch/arm/kernel/entry-armv.S. It is compiled only if _not_
> > defined $(CONFIG_CPU_V7M). It calls nmi_enter() and nmi_stop().
> > It looks like a real NMI handler. This is why I defined HAVE_NMI
> > if (!CPU_V7M).
> > 
> > A solution would be to define HAVE_NMI on all Arm systems and get rid
> > of NEED_PRINTK_NMI. If you think that it would cause less confusion...
> 
> So does this mean that the patch will be updated?

Please, find the follow up patch below. I guess that you will want to
squash it into the [1/n] one.