Product Fault Management,
Continued
these errors do not result in a machine check exception or high
level interrupt (results in device level IPL 14–17 versus error
level IPL 1A, 1D), the VMS machine check handler has a polling
routine that searches for this state at one second intervals. This
results in the host logging a polled error entry.
These conditions cover all of the cases that eventually are handled
by the VMS error handler. The VMS error handler generates
entries that correspond to the machine check exception, hard or
soft error interrupt type, or polled error.
VMS Error
Handling
Upon detection of a machine check exception, hard error interrupt,
soft error interrupt or polled error, VMS performs the following
actions:
Snapshot the state of the kernel.
Disable the caches in most entry points.
Determine if instruction retry is possible if it is a machine
check and if the machine check is recoverable.
Instruction retry is possible if one of the following conditions
is true:
—
If PCSTS <10>PTE_ER = 0:
Verify that (ISTATE2 <07>VR = 1) or (PSL <27> FPD =
1), otherwise crash the system or process depending on
PSL <25:24> Current Mode.
—
If PCSTS <10>PTE_ER = 1:
Verify that (ISTATE2 <07>VR = 1) and (PSL <27>FPD =
0) and (PCSTS <09>PTE_ER_WR = 0), otherwise crash
the system.
ISTATE2 is a longword in the machine check stack frame at
offset (SP)+24; PSL is a longword in the machine check stack
frame at offset (SP)+32; VR is the VAX restart flag; and FPD
is the first part done flag.
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