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authorJoel Sherrill <joel.sherrill@OARcorp.com>2002-05-14 17:45:36 +0000
committerJoel Sherrill <joel.sherrill@OARcorp.com>2002-05-14 17:45:36 +0000
commit48f8968356d2750ee4cda99dcaf9983e47041182 (patch)
tree4c689e26122124b2132bf5c8b87666e4a9548736 /c/src/exec/score/ChangeLog
parent2001-05-14 Joel Sherrill <joel@OARcorp.com> (diff)
downloadrtems-48f8968356d2750ee4cda99dcaf9983e47041182.tar.bz2
2001-05-14 Till Straumann <strauman@slac.stanford.edu>
* src/threaddispatch.c, src/threadhandler.c: Per PR211 fix saving/restoring floating point context. The fpsave and fprestore routines are only used in a executing context which _is_ fp and hence has the FPU enabled. The current behavior required the FPU always to be on which is very dangerous if lazy context switching is used. [Joel Note: Some ports explicitly enabled the FPU in the FP save and restore routines to avoid this.] The patch also makes sure (on powerpc only) that the FPU is disabled for integer tasks. Note that this is crucial if deferred fp context switching is used. Otherwise, fp context corruption may go undetected! Also note that even tasks which merely push/pop FP registers to/from the stack without modifying them still MUST be FP tasks - otherwise (if lazy FP context switching is used), FP register corruption (of other, FP, tasks may occur)! Furthermore, (on PPC) by default, lazy FP context save/restore is _disabled_.
Diffstat (limited to 'c/src/exec/score/ChangeLog')
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diff --git a/c/src/exec/score/ChangeLog b/c/src/exec/score/ChangeLog
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+++ b/c/src/exec/score/ChangeLog
@@ -1,3 +1,24 @@
+2001-05-14 Till Straumann <strauman@slac.stanford.edu>
+
+ * src/threaddispatch.c, src/threadhandler.c: Per PR211 fix
+ saving/restoring floating point context. The fpsave and fprestore
+ routines are only used in a executing context which _is_ fp and hence
+ has the FPU enabled. The current behavior required the FPU always to
+ be on which is very dangerous if lazy context switching is used.
+ [Joel Note: Some ports explicitly enabled the FPU in the FP save and
+ restore routines to avoid this.]
+
+ The patch also makes sure (on powerpc only) that the FPU is disabled
+ for integer tasks. Note that this is crucial if deferred fp context
+ switching is used. Otherwise, fp context corruption may go undetected!
+ Also note that even tasks which merely push/pop FP registers to/from
+ the stack without modifying them still MUST be FP tasks - otherwise
+ (if lazy FP context switching is used), FP register corruption (of
+ other, FP, tasks may occur)!
+
+ Furthermore, (on PPC) by default, lazy FP context save/restore
+ is _disabled_.
+
2001-04-26 Joel Sherrill <joel@OARcorp.com>
* src/objectcomparenamestring.c: Fix typos.