[PATCH] GICv3: Add restart handler to detach CPU from GICv3

[Marc Zyngier]

On Wed, 04 Jan 2023 16:04:14 +0000,
Mark Rutland <mark.rutland at 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 at lakrids:~/src/linux]% ./scripts/get_maintainer.pl -f drivers/irqchip/irq-gic-v3.c
> | Thomas Gleixner <tglx at linutronix.de> (maintainer:IRQCHIP DRIVERS)
> | Marc Zyngier <maz at kernel.org> (maintainer:IRQCHIP DRIVERS)
> | linux-kernel at 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.