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From: Joerg Platte <lists@naasa.net>
Date: Thu, 18 May 2006 18:16:11 +0200
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Subject: [Qemu-devel] fpu problems with qemu-system-sparc
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To: qemu-devel@nongnu.org

Hi!

I've some problems with qemu-system-sparc and programs using floating poi=
nt=20
instructions. Each time at least two floating point programs are started =
in=20
qemu simultaneously, one or both are killed by the linux kernel with a SI=
GSEV=20
signal (sometimes because of a corrupted stack or invalid register values=
).=20
If I start only one program no error occurs. It looks like it has somethi=
ng=20
to do with the disabled-floating-point-unit-trap, which is executed each =
time=20
a process tries to access the fpu while another process has used it befor=
e.=20
This interrupt calls the linux function do_fpd_trap which then saves the =
old=20
FPU-state and restores the new one. When only one program uses the FPU th=
is=20
trap is never executed.

I've checked a lot of the executed instructions in qemu and cannot find a=
ny=20
problems up to now. Does somebody else has an idea what to check? The tes=
t=20
program simply adds two float variables (fadds-instruction) in a loop and=
=20
this crashes the program reproducible.

regards,
J=C3=B6rg