On Wed, Jul 04, 2018 at 01:47:11PM +0100, James Morse wrote: > Hi Akashi, > > On 04/07/18 09:41, takahiro.akashi@xxxxxxxxxx wrote: > > On Tue, Jul 03, 2018 at 09:58:44AM +0100, Marc Zyngier wrote: > >> On 03/07/18 08:01, takahiro.akashi@xxxxxxxxxx wrote: > >>> On Sun, Jun 10, 2018 at 01:24:17PM +0100, Marc Zyngier wrote: > >>>> On Wed, 06 Jun 2018 12:37:02 +0100 James Morse wrote:, > >>>>> Bingo: its the lan78xx driver that is sleeping from the irqchip > >>>>> callbacks; The smsc95xx driver doesn't have a struct irq_chip, which > >>>>> is why the RPi-3-B doesn't do this. > >>>>> > >>>>> It may be valid for kdump to only teardown the 'root irqdomain' (if > >>>>> that even means anything). I assume these secondary irqchip's would > >>>>> have a summary-interrupt that goes to another irqchip. But I can't > >>>>> see a way to tell them apart.., > > >>>> Overall, I can't think of an easy fix. We have a few options, but none > >>>> of them involve a centralised change: > >>>> > >>>> 1) We provide a reset infrastructure for irqchips, with an opt-in > >>>> mechanism. This involves changing the way we teardown irqs at > >>>> crash-time, and we'd then need some notion of reset ordering (think > >>>> of the layered ITS and GICv3, for example). > >>> > >>> Does this mean that all the irqchips have to be implemented with reset? > >> > >> No. Only those that want to be reset at kexec time. > > > > I don't get the point yet. > > (this stuff is new to me, below terminology is probably wrong:) > > It seems there is actually a tree of irqchips, which feed interrupts through the > tree via some summary-interrupt. > The problem is one of these later-irqchips is on the other end of the USB bus, > and requires a fair amount of sleeping in order to reset it. > > The trick is everything comes through the root irqchip. So we can reset that to > disable all the other interrupts in this tree. > > This only works until the new kernel re-enables the summary-interrupt, it needs > to reset the irqchip that the summary-interrupt leads to first. > > (I assume shared summary-interrupts are somehow forbidden). So you are choking at the "root" irqchip? Is this safe when a new (kdump) kernel starts up and re-initialises irq hierarchy? -Takahiro AKASHI > > > Who should have reset interface? > > What is the criteria? > > (reset-interface -> be reset at kdump time) > > Just the root irchip that all interrupts have to come through. > > > Thanks, > > James _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
