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From: Peter Zijlstra <peterz@infradead.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>,
	Dave Hansen <dave@sr71.net>,
	hpa@zytor.com, tglx@linutronix.de, torvalds@linux-foundation.org,
	linux-kernel@vger.kernel.org, dwmw@amazon.co.uk,
	linux-tip-commits@vger.kernel.org, Borislav Petkov <bp@alien8.de>,
	Arjan van de Ven <arjan@infradead.org>
Subject: Re: [PATCH] watchdog: hpwdt: Remove spinlock acquire and BIOS calls from NMI context
Date: Wed, 14 Feb 2018 10:38:35 +0100	[thread overview]
Message-ID: <20180214093835.GW25181@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180214093159.mdzfupne547bi5qx@gmail.com>

On Wed, Feb 14, 2018 at 10:31:59AM +0100, Ingo Molnar wrote:
> Because in this particular case it does not appear to be so: the reason for the 
> BIOS/firmware call appears to be to determine how we nmi_panic() after receiving 
> an NMI that no other NMI handler handled: with a passive-aggressive "I don't know" 
> panic message or with a slightly more informative panic message.

However much I like just ripping all that out, I think the ROM call
actually does that logging, or that is how I read things.

If you look at the original Changelog for that driver:

    Hp is providing a Hardware WatchDog Timer driver that will only work with the
    specific HW Timer located in the HP ProLiant iLO 2 ASIC. The iLO 2 HW Timer
    will generate a Non-maskable Interrupt (NMI) 9 seconds before physically
    resetting the server, by removing power, so that the event can be logged to
    the HP Integrated Management Log (IML), a Non-Volatile Random Access Memory
    (NVRAM). The logging of the event is performed using the HP ProLiant ROM via
    an Industry Standard access known as a BIOS Service Directory Entry.

  reply	other threads:[~2018-02-14  9:38 UTC|newest]

Thread overview: 74+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-10 23:39 [PATCH v2 0/6] Spectre v2 updates David Woodhouse
2018-02-10 23:39 ` [PATCH v2 1/6] x86/speculation: Update Speculation Control microcode blacklist David Woodhouse
2018-02-11 12:08   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-02-12  9:50   ` [PATCH v2 1/6] " Darren Kenny
2018-02-12 14:16   ` David Woodhouse
2018-02-12 14:32     ` Thomas Gleixner
2018-02-10 23:39 ` [PATCH v2 2/6] Revert "x86/speculation: Simplify indirect_branch_prediction_barrier()" David Woodhouse
2018-02-11 12:09   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-02-13  8:58   ` tip-bot for David Woodhouse
2018-02-13  9:41     ` Peter Zijlstra
2018-02-13 11:28       ` Ingo Molnar
2018-02-13 13:28         ` Peter Zijlstra
2018-02-13 13:38           ` Ingo Molnar
2018-02-13 15:26           ` [tip:x86/pti] x86/speculation: Add <asm/msr-index.h> dependency tip-bot for Peter Zijlstra
2018-02-15  0:28           ` tip-bot for Peter Zijlstra
2018-02-10 23:39 ` [PATCH v2 3/6] KVM: x86: Reduce retpoline performance impact in slot_handle_level_range() David Woodhouse
2018-02-11 12:09   ` [tip:x86/pti] KVM/x86: Reduce retpoline performance impact in slot_handle_level_range(), by always inlining iterator helper methods tip-bot for David Woodhouse
2018-02-13  8:58   ` tip-bot for David Woodhouse
2018-02-10 23:39 ` [PATCH v2 4/6] X86/nVMX: Properly set spec_ctrl and pred_cmd before merging MSRs David Woodhouse
2018-02-11 12:10   ` [tip:x86/pti] " tip-bot for KarimAllah Ahmed
2018-02-13  8:59   ` tip-bot for KarimAllah Ahmed
2018-02-10 23:39 ` [PATCH v2 5/6] KVM/nVMX: Set the CPU_BASED_USE_MSR_BITMAPS if we have a valid L02 MSR bitmap David Woodhouse
2018-02-11 10:19   ` Ingo Molnar
     [not found]     ` <1518345844.3677.365.camel@amazon.co.uk>
2018-02-11 10:55       ` Ingo Molnar
2018-02-11 12:10   ` [tip:x86/pti] " tip-bot for KarimAllah Ahmed
2018-02-13  8:59   ` tip-bot for KarimAllah Ahmed
2018-02-10 23:39 ` [PATCH v2 6/6] x86/speculation: Use IBRS if available before calling into firmware David Woodhouse
2018-02-11 11:46   ` Ingo Molnar
2018-02-11 10:41 ` [PATCH v2 0/6] Spectre v2 updates Ingo Molnar
2018-02-11 15:19 ` [PATCH v2.1] x86/speculation: Use IBRS if available before calling into firmware David Woodhouse
2018-02-11 18:50   ` [PATCH] x86/speculation: Clean up various Spectre related details Ingo Molnar
2018-02-11 19:25     ` David Woodhouse
2018-02-11 19:43       ` Ingo Molnar
2018-02-12 15:30         ` David Woodhouse
2018-02-13  8:04           ` Ingo Molnar
2018-02-11 19:19   ` [tip:x86/pti] x86/speculation: Use IBRS if available before calling into firmware tip-bot for David Woodhouse
2018-02-12  5:59     ` afzal mohammed
2018-02-12 16:30       ` David Woodhouse
2018-02-12 10:22     ` Ingo Molnar
2018-02-12 11:50       ` Peter Zijlstra
2018-02-12 12:27         ` David Woodhouse
2018-02-12 13:06           ` Peter Zijlstra
2018-02-13  7:58           ` Ingo Molnar
2018-02-12 12:28         ` Peter Zijlstra
2018-02-12 16:13       ` Dave Hansen
2018-02-12 16:58         ` Peter Zijlstra
2018-02-13  7:55           ` Ingo Molnar
2018-02-14  1:49             ` Tim Chen
2018-02-14  8:56               ` Peter Zijlstra
2018-02-14  8:57                 ` Peter Zijlstra
2018-02-14 19:20                 ` Tim Chen
2018-02-14 23:19                   ` Ingo Molnar
2018-02-15  2:01                     ` Tim Chen
2018-02-14  9:31               ` [PATCH] watchdog: hpwdt: Remove spinlock acquire and BIOS calls from NMI context Ingo Molnar
2018-02-14  9:38                 ` Peter Zijlstra [this message]
2018-02-14 10:39                   ` Ingo Molnar
2018-02-14  9:44                 ` Borislav Petkov
2018-02-14 18:13                   ` Jerry Hoemann
2018-02-14 23:17                     ` Ingo Molnar
2018-02-15 17:44                       ` Jerry Hoemann
2018-02-15 19:02                         ` Ingo Molnar
2018-02-15 19:48                         ` Peter Zijlstra
2018-02-16 18:44     ` [tip:x86/pti] x86/speculation: Use IBRS if available before calling into firmware Tim Chen
2018-02-16 19:16       ` David Woodhouse
2018-02-16 23:46         ` Tim Chen
2018-02-17 10:26           ` Ingo Molnar
2018-02-19  9:20             ` Peter Zijlstra
2018-02-19  9:29               ` David Woodhouse
2018-02-19  9:39                 ` Ingo Molnar
2018-02-19  9:44                   ` David Woodhouse
2018-02-19 10:08                 ` Peter Zijlstra
2018-02-19  9:36               ` Ingo Molnar
2018-02-12  8:27 ` [PATCH v2 0/6] Spectre v2 updates Paolo Bonzini
2018-02-13  7:59   ` Ingo Molnar

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