All the kernel debug style tools (kdb, kgdb, nlkd, netdump, lkcd,
crash, kdump etc.) have a common requirement, they need to do a crash
stop of the systems. This means stopping all the cpus, even if some of
the cpus are spinning disabled. In addition, each cpu has to save
enough state to start the diagnosis of the problem.
* Each debug style tool has written its own code for interrupting the
other cpus and for saving cpu state.
* Some tools try a normal IPI first then send a non-maskable interrupt
after a delay.
* Some tools always send a NMI first, which can result in incomplete or
wrong machine state if NMI arrives at the wrong time.
* Most of the tools do not know how to cope with the IA64 architecture
defined rendezvous algorithm, which interferes with an OS driven
rendezvous.
* Needless to say, every single patch set conflicts with all the
others, which makes it very difficult to install more than one of the
tools at a time.
The solution is to define a common crash_stop API that can be used by
_all_ of the debug style tools, without reinventing the wheel each
time. The following crash_stop patches implement this API for i386,
x86_64 and ia64. It correctly handles the complicated ia64 algorithm
for MCA and INIT, unlike almost every current debug style tool.
Adding other architectures is a fairly simple matter, define
the IPI and NMI routines (the crash_stop_$(ARCH)_handlers patch),
intercept the events that indicate that the system is dying (the
crash_stop_$(ARCH) patch), update the Kconfig entry for CRASH_STOP to
add the new $(ARCH).
Most of the design documentation is in the crash_stop_common patch.
Please read that before replying.
crash_stop_header The architecture independent header.
crash_stop_common The architecture independent code.
crash_stop_i386_handlers i386 specific code to send and respond
to the crash_stop IPI and NMI.
crash_stop_i386 i386 specific code to intercept events
that indicate that the system is dying.
crash_stop_x86_64_nmiwatchdog i386 creates an event for NMI watchdog,
it is missing from x86_64. Add
DIE_NMIWATCHDOG to x86_64.
crash_stop_x86_64_handlers x86_64 specific code to send and
respond to the crash_stop IPI and NMI.
crash_stop_x86_64 x86_64 specific code to intercept
events that indicate that the system is
dying.
crash_stop_ia64_handlers ia64 specific code to send and respond
to the crash_stop IPI and NMI.
crash_stop_ia64 ia64 specific code to intercept events
that indicate that the system is dying.
crash_stop_common_Kconfig Add crash_stop to the config system.
Only for i386, x86_64 and ia64 at the
moment, extend as new architectures are
added.
crash_stop_demo A demonstration of using crash_stop in
a debug style tool. Not for inclusion
in the kernel.
crash_stop_test Test the crash_stop code. Not for
inclusion in the kernel.
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