[fpc-devel] vfp exception issues with freepascal
plugwash at p10link.net
Sat Jul 28 17:42:25 CEST 2012
I am involved in a project called raspbian to produce a hard-float
derivative of debian for the raspberry pi. Within this port we had
problems with floating point exceptions while running the compiler.
These problems were tracked down by masta (a freepascal upstream
developer) to reversed logic in a routine for controlling floating point
exception settings (attempting to disable an exception enabled it and
Howevr this then left the question of "why didn't I see this problem
when preparing the freepascal packages for debian armhf?". The
conclusion i've come to is that on the armv7 systems i've tested (a
beagleboard XM running 220.127.116.11-x2 and an IMX53 quickstart board running
) the method freepascal uses for enabling vfp exceptions simply doesn't
I've written a small test program in C and inline assembler to
demonstrate this. It tries to enable a number of floating point
exceptions using a price of inline assembly I copied from the freepascal
run time library and then does a division of the command line arguments.
When I test this on a Pi running raspbian I get a floating point
exception as expected.
root at raspbian:~# ./a.out 1 0
Floating point exception
root at raspbian:~#
but when I try it on my beagleboard XM or IMX53 board I don't get any
root at plugwash:/home/plugwash# ./a.out 1 0
root at plugwash:/home/plugwash#
Any vfp experts able to help get to the bottom of what is going on here?
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