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From: Marc Zyngier <maz@kernel.org>
To: Mark Rutland <mark.rutland@arm.com>,
	 Joakim Tjernlund <Joakim.Tjernlund@infinera.com>
Cc: "linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] GICv3: Add restart handler to detach CPU from GICv3
Date: Wed, 04 Jan 2023 16:50:23 +0000	[thread overview]
Message-ID: <86pmbu6y7k.wl-maz@kernel.org> (raw)
In-Reply-To: <Y7Wjfu0NHDMzwf9b@FVFF77S0Q05N>

On Wed, 04 Jan 2023 16:04:14 +0000,
Mark Rutland <mark.rutland@arm.com> wrote:
> 
> On Tue, Jan 03, 2023 at 04:27:07PM +0000, Joakim Tjernlund wrote:
> > On Fri, 2022-12-16 at 17:21 +0100, Joakim Tjernlund wrote:
> > 
> > Ping?
> 
> To whom?
> 
> You don't appeared to have Cc'd any relevant maintainer, and people are still
> on holiday, so it's extremely likely this will be missed.

That, plus nobody reads the list looking for this sort of things.

> 
> For the maintainer, please use scripts/get_maintainer.pl, e.g.
> 
> | [mark@lakrids:~/src/linux]% ./scripts/get_maintainer.pl -f drivers/irqchip/irq-gic-v3.c
> | Thomas Gleixner <tglx@linutronix.de> (maintainer:IRQCHIP DRIVERS)
> | Marc Zyngier <maz@kernel.org> (maintainer:IRQCHIP DRIVERS)
> | linux-kernel@vger.kernel.org (open list:IRQCHIP DRIVERS)
> 
> Note: I've Cc'd Marc, who wrote the GICv3 driver.

Cheers Mark, much appreciated.

> 
> > > Needed for reboot without resetting the whole GIC
> 
> This doesn't really explain what you're trying to do nor why.
> 
> Why do you need to "reboot without resetting the whole GIC" ?
> 
> Do you encounter a problem if we try to reset the whole GIC?
> 
> Is this for kexec?
> 
> Is this for some use-case enabled by out-of-tree code?

All valid questions. This smells of a terrible hack...

The interesting aspect is that this is only done when DS=1, probably
meaning that they are doing this in a VM. it also rely on some
(unbounded) UNPRED behaviour as ProcessorSleep is entered without
any consideration for Group0... Good luck with that.

Anyway, I don't think we want any of this stuff. Certainly not without
a cast-iron justification.

	M.

-- 
Without deviation from the norm, progress is not possible.

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  reply	other threads:[~2023-01-04 16:53 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-16 16:21 [PATCH] GICv3: Add restart handler to detach CPU from GICv3 Joakim Tjernlund
2023-01-03 16:27 ` Joakim Tjernlund
2023-01-04 16:04   ` Mark Rutland
2023-01-04 16:50     ` Marc Zyngier [this message]
2023-01-04 17:23       ` Joakim Tjernlund
2023-01-04 18:48         ` Marc Zyngier
2023-01-04 19:52           ` Joakim Tjernlund
2023-01-05 10:37             ` Marc Zyngier

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