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Floating Point Register saves
- From: David Brennan <eCos at brennanhome dot com>
- To: eCos Discuss <ecos-discuss at sources dot redhat dot com>
- Date: Mon, 27 Sep 2004 19:11:46 -0700
- Subject: [ECOS] Floating Point Register saves
According to the documentation in the i386 hal cdl documentation, it
states that by default eCos will "save and restore FPU state on every
thread switch, interrupt and exception." It states this in the option
for turning off lazy FPU switching. Our application uses floating point
registers in the DSR context. With Lazy FPU on, we get an SIGFPE. (Which
I guess is not surprising). So we have turned off lazy FPU switching.
With lazy FPU off, is it safe to use floating points in DSR (or ISR)
context? (We got burned by this earlier under VxWorks.)
If not, is there a preferred way of saving, and restoring the floating
point registers?
Thanks
David Brennan
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