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2008-07-10 Till Straumann <strauman@slac.stanford.edu>

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* new-exceptions/bspsupport/README: added more information
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Till Straumann
2008-07-10 21:28:38 +00:00
parent 2c3a9c1679
commit 055173d46a
1 changed files with 16 additions and 0 deletions
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c/src/lib/libcpu/powerpc/new-exceptions/bspsupport/README
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@@ -388,3 +388,19 @@ RACE CONDITION WHEN DEALING WITH CRITICAL INTERRUPTS
handler would not, eventually, check for a handler would not, eventually, check for a
dispatch requirement). dispatch requirement).
And one more note: We never want to disable
machine-check exceptions to avoid a checkstop.
This means that we cannot use enabling/disabling
this type of exception for protection of critical
OS data structures.
Therefore, calling OS primitives from a asynchronous
machine-check handler is ILLEGAL and not supported.
Since machine-checks can happen anytime it is not
legal to test if a deferred context switch should
be performed when the asynchronous machine-check
handler returns (since _Context_Switch_is_necessary
could have been set by a IRQ-protected section of
code that was hit by the machine-check).
Note that synchronous machine-checks can legally
use OS primitives and currently there are no
asynchronous machine-checks defined.