Different behaviour of RTEMS in QEMU/i386 and SPARC

Joel Sherrill joel.sherrill at OARcorp.com
Mon Oct 31 11:26:05 UTC 2011

QEMU for i386 has FP issues which are not present on real hardware. It does not maintain enough precision to make some of the Ada ACATS tests pass. I investigated those failures and it was the simulator. Any test which depends on very accurate IEEE754 is not going to be happy on qemu i386.


"Constantine "chicky" Giotopoulos" <kotsosgiotopoulos at gmail.com> wrote:

>The original program is not using any RTEMS directives, it's just a bunch of functions that execute floating point operations, that can be compiled and run on any machine with a compiler. The only option needed when compiling it is "-lm" because it utilizes the "math.h" library. Since its execution is proceeding normally means that the CPU is able to handle the operations. Even if the CPU couldn't handle the operation, it would have presented somekind of "defect" of "flaw" message.
>When I modified the program in order to execute "paranoia's" functions through a single RTEMS task, at the point indicated the execution seems to freeze, as if it encounters an infinite loop or something else that prevents it from continuing. Something that is not the case when executing the same code on the SPARC machine.
>On Mon, Oct 31, 2011 at 11:38 AM, Sebastian Huber <sebastian.huber at embedded-brains.de<mailto:sebastian.huber at embedded-brains.de>> wrote:
>On 10/31/2011 11:27 AM, Constantine "chicky" Giotopoulos wrote:
>I doubt that this is the case overall, because when I compile the (original)
>program and run it outside of Qemu on an Intel machine, it doesn't freeze, it
>runs until the end.
>How do you compile it to run it outside of Qemu?
>Sebastian Huber, embedded brains GmbH
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