Messages in this thread | | | Date | Mon, 07 Aug 2023 11:47:04 +0100 | From | Marc Zyngier <> | Subject | Re: [PATCH v9 7/7] arm64: kgdb: Roundup cpus using the debug IPI |
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On 2023-08-07 11:28, Mark Rutland wrote: > On Thu, Jun 01, 2023 at 02:31:51PM -0700, Douglas Anderson wrote: >> From: Sumit Garg <sumit.garg@linaro.org> >> >> Let's use the debug IPI for rounding up CPUs in kgdb. When the debug >> IPI is backed by an NMI (or pseudo NMI) then this will let us debug >> even hard locked CPUs. When the debug IPI isn't backed by an NMI then >> this won't really have any huge benefit but it will still work. >> >> Signed-off-by: Sumit Garg <sumit.garg@linaro.org> >> Signed-off-by: Douglas Anderson <dianders@chromium.org> >> --- >> >> Changes in v9: >> - Remove fallback for when debug IPI isn't available. >> - Renamed "NMI IPI" to "debug IPI" since it might not be backed by >> NMI. >> >> arch/arm64/kernel/ipi_debug.c | 5 +++++ >> arch/arm64/kernel/kgdb.c | 14 ++++++++++++++ >> 2 files changed, 19 insertions(+) > > This looks fine to me, but I'd feel a bit happier if we had separate > SGIs for > the backtrace and the KGDB callback as they're logically unrelated.
Well, we're a bit stuck here.
We have exactly *one* spare SGI with GICv3, as we lose 8 of them to the secure side. One possibility would be to mux some of the lesser used IPIs onto two SGIs (one with standard priority, and one with NMI priority).
M. -- Jazz is not dead. It just smells funny...
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