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From: Marc Zyngier <maz@kernel.org>
To: Sumit Garg <sumit.garg@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Daniel Thompson <daniel.thompson@linaro.org>,
	Jason Cooper <jason@lakedaemon.net>,
	Catalin Marinas <catalin.marinas@arm.com>,
	ito-yuichi@fujitsu.com, Douglas Anderson <dianders@chromium.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	julien.thierry.kdev@gmail.com,
	Jason Wessel <jason.wessel@windriver.com>,
	kgdb-bugreport@lists.sourceforge.net,
	Thomas Gleixner <tglx@linutronix.de>,
	Masayoshi Mizuma <msys.mizuma@gmail.com>,
	Will Deacon <will@kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v5 1/5] arm64: Add framework to turn IPI as NMI
Date: Tue, 20 Oct 2020 11:08:30 +0100	[thread overview]
Message-ID: <f3596e3ed70737d36f72056827d7d441@kernel.org> (raw)
In-Reply-To: <CAFA6WYPEw5x_3zDZSnkL23YjFWbF=VkUKefM6Ts46JLVaj2sDA@mail.gmail.com>

On 2020-10-20 07:43, Sumit Garg wrote:
> On Mon, 19 Oct 2020 at 17:07, Marc Zyngier <maz@kernel.org> wrote:

[...]

>> > +{
>> > +     if (!ipi_desc)
>> > +             return;
>> > +
>> > +     if (is_nmi) {
>> > +             if (!prepare_percpu_nmi(ipi_id))
>> > +                     enable_percpu_nmi(ipi_id, IRQ_TYPE_NONE);
>> > +     } else {
>> > +             enable_percpu_irq(ipi_id, IRQ_TYPE_NONE);
>> 
>> I'm not keen on this. Normal IRQs can't reliably work, so why do you
>> even bother with this?
> 
> Yeah I agree but we need to support existing functionality for kgdb
> roundup and sysrq backtrace using normal IRQs as well.

When has this become a requirement? I don't really see the point in
implementing something that is known not to work.

         M.
-- 
Jazz is not dead. It just smells funny...

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WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Sumit Garg <sumit.garg@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Jason Cooper <jason@lakedaemon.net>,
	Mark Rutland <mark.rutland@arm.com>,
	julien.thierry.kdev@gmail.com,
	Douglas Anderson <dianders@chromium.org>,
	Daniel Thompson <daniel.thompson@linaro.org>,
	Jason Wessel <jason.wessel@windriver.com>,
	Masayoshi Mizuma <msys.mizuma@gmail.com>,
	ito-yuichi@fujitsu.com, kgdb-bugreport@lists.sourceforge.net,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v5 1/5] arm64: Add framework to turn IPI as NMI
Date: Tue, 20 Oct 2020 11:08:30 +0100	[thread overview]
Message-ID: <f3596e3ed70737d36f72056827d7d441@kernel.org> (raw)
In-Reply-To: <CAFA6WYPEw5x_3zDZSnkL23YjFWbF=VkUKefM6Ts46JLVaj2sDA@mail.gmail.com>

On 2020-10-20 07:43, Sumit Garg wrote:
> On Mon, 19 Oct 2020 at 17:07, Marc Zyngier <maz@kernel.org> wrote:

[...]

>> > +{
>> > +     if (!ipi_desc)
>> > +             return;
>> > +
>> > +     if (is_nmi) {
>> > +             if (!prepare_percpu_nmi(ipi_id))
>> > +                     enable_percpu_nmi(ipi_id, IRQ_TYPE_NONE);
>> > +     } else {
>> > +             enable_percpu_irq(ipi_id, IRQ_TYPE_NONE);
>> 
>> I'm not keen on this. Normal IRQs can't reliably work, so why do you
>> even bother with this?
> 
> Yeah I agree but we need to support existing functionality for kgdb
> roundup and sysrq backtrace using normal IRQs as well.

When has this become a requirement? I don't really see the point in
implementing something that is known not to work.

         M.
-- 
Jazz is not dead. It just smells funny...

  reply	other threads:[~2020-10-20 10:09 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-14 11:12 [PATCH v5 0/5] arm64: Add framework to turn an IPI as NMI Sumit Garg
2020-10-14 11:12 ` Sumit Garg
2020-10-14 11:12 ` [PATCH v5 1/5] arm64: Add framework to turn " Sumit Garg
2020-10-14 11:12   ` Sumit Garg
2020-10-15  1:15   ` Masayoshi Mizuma
2020-10-15  1:15     ` Masayoshi Mizuma
2020-10-19 11:37   ` Marc Zyngier
2020-10-19 11:37     ` Marc Zyngier
2020-10-20  6:43     ` Sumit Garg
2020-10-20  6:43       ` Sumit Garg
2020-10-20 10:08       ` Marc Zyngier [this message]
2020-10-20 10:08         ` Marc Zyngier
2020-10-20 11:22         ` Sumit Garg
2020-10-20 11:22           ` Sumit Garg
2020-10-20 12:25           ` Daniel Thompson
2020-10-20 12:25             ` Daniel Thompson
2020-10-20 12:32             ` Marc Zyngier
2020-10-20 12:32               ` Marc Zyngier
2020-10-21  5:22               ` Sumit Garg
2020-10-21  5:22                 ` Sumit Garg
2020-10-21 10:27           ` Marc Zyngier
2020-10-21 10:27             ` Marc Zyngier
2020-10-22 11:52             ` Sumit Garg
2020-10-22 11:52               ` Sumit Garg
2020-10-19 11:56   ` Marc Zyngier
2020-10-19 11:56     ` Marc Zyngier
2020-10-20  7:07     ` Sumit Garg
2020-10-20  7:07       ` Sumit Garg
2020-10-14 11:12 ` [PATCH v5 2/5] irqchip/gic-v3: Enable support for SGIs to act as NMIs Sumit Garg
2020-10-14 11:12   ` Sumit Garg
2020-10-15  1:16   ` Masayoshi Mizuma
2020-10-15  1:16     ` Masayoshi Mizuma
2020-10-19 12:07   ` Marc Zyngier
2020-10-19 12:07     ` Marc Zyngier
2020-10-20  7:24     ` Sumit Garg
2020-10-20  7:24       ` Sumit Garg
2020-10-14 11:12 ` [PATCH v5 3/5] arm64: smp: Allocate and setup IPI as NMI Sumit Garg
2020-10-14 11:12   ` Sumit Garg
2020-10-15  1:16   ` Masayoshi Mizuma
2020-10-15  1:16     ` Masayoshi Mizuma
2020-10-19 11:59   ` Marc Zyngier
2020-10-19 11:59     ` Marc Zyngier
2020-10-20  7:16     ` Sumit Garg
2020-10-20  7:16       ` Sumit Garg
2020-10-14 11:12 ` [PATCH v5 4/5] arm64: kgdb: Round up cpus using " Sumit Garg
2020-10-14 11:12   ` Sumit Garg
2020-10-19 12:15   ` Marc Zyngier
2020-10-19 12:15     ` Marc Zyngier
2020-10-20  8:51     ` Sumit Garg
2020-10-20  8:51       ` Sumit Garg
2020-10-14 11:12 ` [PATCH v5 5/5] arm64: ipi_nmi: Add support for NMI backtrace Sumit Garg
2020-10-14 11:12   ` Sumit Garg
2020-10-15  1:17   ` Masayoshi Mizuma
2020-10-15  1:17     ` Masayoshi Mizuma
2020-10-19 12:20   ` Marc Zyngier
2020-10-19 12:20     ` Marc Zyngier
2020-10-20  9:13     ` Sumit Garg
2020-10-20  9:13       ` Sumit Garg
2020-10-21 10:32       ` Marc Zyngier
2020-10-21 10:32         ` Marc Zyngier
2020-10-21 11:28         ` Sumit Garg
2020-10-21 11:28           ` Sumit Garg

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