On Wed, 17 Feb 2021 11:49:23 +0000, Mark Rutland <mark.rutland@xxxxxxx> wrote: > > Hi Hector, > > On Mon, Feb 15, 2021 at 09:16:57PM +0900, Hector Martin wrote: > > From: Marc Zyngier <maz@xxxxxxxxxx> > > > > By default, FIQ exceptions trigger a panic. On platforms that need to > > deliver interrupts via FIQ, this gets redirected via an alternative to > > instead handle FIQ the same way as IRQ. It is up to the irqchip handler > > to discriminate between the two. > > > > Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx> > > Signed-off-by: Hector Martin <marcan@xxxxxxxxx> > > Since the use of FIQ is a platform integration detail rather than a CPU > implementation detail (and e.g. can differ across bare-metal and VM), > I'd prefer to always have separate registered handlers for IRQ/FIQ (also > avoiding the need for patching). That way we can explicitly opt-in to > FIQ when required, and avoid edge-cases where an unexpected FIQ could > livelock an unaware IRQ handler. > > Marc and I had a quick play with that, and I have a series of patches > I've pushed to: > > https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/log/?h=arm64/fiq > git://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git arm64/fiq > > ... which I'll post out shortly. FWIW, I've just posted a more complete version of the first patch in this series[1], which you may want to use directly (though I plan to take it as a fix for 5.12). Thanks, M. [1] https://lore.kernel.org/r/20210217142800.2547737-1-maz@xxxxxxxxxx -- Without deviation from the norm, progress is not possible.
