fenv support vs. SMP systems
Sebastian Huber
sebastian.huber@embedded-brains.de
Mon Jul 13 06:19:03 GMT 2020
Hello,
the new fenv support alters usually some floating-point status and
control register. This register is usually specific to the processor
executing the code. In an SMP system, the current approach can lead to
an inconsistent system if the register is not included in the thread
context (for example in RTEMS these registers are considered to be
system wide and are only initialized during the system startup). What do
I mean with inconsistent system? For example, you set the rounding mode
on processor A to from X (= default) to Y, then the you migrate to
processor B and suddenly use the default rounding mode X. Another
example is to do a division by zero on processor A and then migrate to
processor B and check the exception flags.
--
Sebastian Huber, embedded brains GmbH
Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone : +49 89 189 47 41-16
Fax : +49 89 189 47 41-09
E-Mail : sebastian.huber@embedded-brains.de
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