arch/ia64/mca.rst

2 An ad-hoc collection of notes on IA64 MCA and INIT processing
9 MCA/INIT are completely asynchronous.  They can occur at any time, when
11 holding a spinlock.  Trying to get any lock from MCA/INIT state is
32   sends an unmaskable INIT event to the slave cpus that have not
35 * Because MCA/INIT can be delivered at any time, including when the cpu
37   event are _completely_ undefined.  In particular the MCA/INIT
40   TP on return.  However MCA/INIT events expose us to these PAL
43 * If an MCA/INIT event occurs while the kernel was running (not user
44   space) and the kernel has called PAL then the MCA/INIT handler cannot
47   Because the MCA/INIT handlers cannot trust the kernel stack, they
48   have to use their own, per-cpu stacks.  The MCA/INIT stacks are
70   INIT event are no longer running, they have been converted to blocked
76   switches to an MCA/INIT stack, registers its new stack using
81 * MCA/INIT can be nested, to a depth of 2 on any cpu.  In the case of a
82   nested error, we want diagnostics on the MCA/INIT handler that
84   requires set_curr_task() so the MCA/INIT handlers can register their
90     struct task and the kernel stacks.  Then the MCA/INIT data would be
95     stacks meant separate "tasks" for the MCA/INIT handlers.
99 INIT is less complicated than MCA.  Pressing the nmi button or using
100 the equivalent command on the management console sends INIT to all
102 slaves.  All the OS INIT handlers are entered at approximately the same
111 SAL on resume.  The OS INIT code has workarounds for some of these
117 violations.  Unfortunately MCA/INIT start off as massive layer
127 How is ia64 MCA/INIT different from x86 NMI?
129 * x86 NMI typically gets delivered to one cpu.  MCA/INIT gets sent to
132 * x86 NMI cannot be nested.  MCA/INIT can be nested, to a depth of 2
140   about any registers having changed.  MCA/INIT can occur while the cpu
150 What happens when MCA/INIT is delivered what a cpu is running user
153 The user mode registers are stored in the RSE area of the MCA/INIT on
155 mode registers are preserved across a recoverable MCA/INIT.  Since the
157 MCA/INIT never tries to backtrace user space.  Which means that the OS
166 How do we get a backtrace on the tasks that were running when MCA/INIT
171 the MCA/INIT stack's RSE to the original stack's RSE, copies the
181 How do we identify the tasks that were running when MCA/INIT was
185 state, then sos->prev_task on the MCA/INIT stack is updated to point to
190 The sos data is always in the MCA/INIT handler stack, at offset
195 Also the comm field of the MCA/INIT task is modified to include the pid