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 for <linuxppc-dev@lists.ozlabs.org>; Wed, 13 Jun 2018 18:42:35 +1000 (AEST)
Date: Wed, 13 Jun 2018 10:42:19 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
 Thomas Gleixner <tglx@linutronix.de>,
 Ingo Molnar <mingo@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
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 linux-kernel@vger.kernel.org, Jacob Pan <jacob.jun.pan@intel.com>,
 Don Zickus <dzickus@redhat.com>, Michael Ellerman <mpe@ellerman.id.au>,
 Frederic Weisbecker <frederic@kernel.org>,
 Babu Moger <babu.moger@oracle.com>,
 "David S. Miller" <davem@davemloft.net>,
 Benjamin Herrenschmidt <benh@kernel.crashing.org>,
 Paul Mackerras <paulus@samba.org>,
 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
 Masami Hiramatsu <mhiramat@kernel.org>,
 Andrew Morton <akpm@linux-foundation.org>,
 Philippe Ombredanne <pombredanne@nexb.com>,
 Colin Ian King <colin.king@canonical.com>,
 "Luis R. Rodriguez" <mcgrof@kernel.org>, iommu@lists.linux-foundation.org
Subject: Re: [RFC PATCH 12/23] kernel/watchdog: Introduce a struct for NMI
 watchdog operations
Message-ID: <20180613084219.GT12258@hirez.programming.kicks-ass.net>
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On Wed, Jun 13, 2018 at 05:41:41PM +1000, Nicholas Piggin wrote:
> On Tue, 12 Jun 2018 17:57:32 -0700
> Ricardo Neri <ricardo.neri-calderon@linux.intel.com> wrote:
> 
> > Instead of exposing individual functions for the operations of the NMI
> > watchdog, define a common interface that can be used across multiple
> > implementations.
> > 
> > The struct nmi_watchdog_ops is defined for such operations. These initial
> > definitions include the enable, disable, start, stop, and cleanup
> > operations.
> > 
> > Only a single NMI watchdog can be used in the system. The operations of
> > this NMI watchdog are accessed via the new variable nmi_wd_ops. This
> > variable is set to point the operations of the first NMI watchdog that
> > initializes successfully. Even though at this moment, the only available
> > NMI watchdog is the perf-based hardlockup detector. More implementations
> > can be added in the future.
> 
> Cool, this looks pretty nice at a quick glance. sparc and powerpc at
> least have their own NMI watchdogs, it would be good to have those
> converted as well.

Yeah, agreed, this looks like half a patch.

> Is hpet a cross platform thing, or just x86? We should avoid
> proliferation of files under kernel/ I think, so with these watchdog
> driver structs then maybe implementations could go in drivers/ or
> arch/

HPET is mostly an x86 thing (altough it can be found elsewhere), but the
whole thing relies on the x86 NMI mechanism and is thus firmly arch/
material (like the sparc and ppc thing).