a07a594152
Some MediaTek devices have broken firmware which corrupts some GICR registers behind the back of the OS, and pseudo-NMIs cannot be used on these devices. For more details see commit:44bd78dd2b("irqchip/gic-v3: Disable pseudo NMIs on Mediatek devices w/ firmware issues") We did not take this problem into account in commit:331a1b3a83("arm64: smp: Add arch support for backtrace using pseudo-NMI") Since that commit arm64's SMP code will try to setup some IPIs as pseudo-NMIs, even on systems with broken FW. The GICv3 code will (rightly) reject attempts to request interrupts as pseudo-NMIs, resulting in boot-time failures. Avoid the problem by taking the broken FW into account when deciding to request IPIs as pseudo-NMIs. The GICv3 driver maintains a static_key named "supports_pseudo_nmis" which is false on systems with broken FW, and we can consult this within ipi_should_be_nmi(). Fixes:331a1b3a83("arm64: smp: Add arch support for backtrace using pseudo-NMI") Reported-by: Chen-Yu Tsai <wenst@chromium.org> Closes: https://issuetracker.google.com/issues/197061987#comment68 Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Douglas Anderson <dianders@chromium.org> Tested-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Marc Zyngier <maz@kernel.org> Tested-by: Chen-Yu Tsai <wenst@chromium.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.