From: Sebastian Huber <sebastian.huber@embedded-brains.de>
To: Newlib <newlib@sourceware.org>
Subject: fenv support vs. SMP systems
Date: Mon, 13 Jul 2020 08:19:03 +0200 [thread overview]
Message-ID: <d1d42490-7464-2613-09f8-d163583bdb49@embedded-brains.de> (raw)
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
PGP : Public key available on request.
Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.
next reply other threads:[~2020-07-13 6:19 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-13 6:19 Sebastian Huber [this message]
2020-07-13 13:00 ` Joel Sherrill
2020-07-13 17:16 ` Joseph Myers
2020-07-13 21:03 ` Joel Sherrill
2020-07-14 5:16 ` Sebastian Huber
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