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Switch FPU emulator trap to BREAK instruction

Subject: Switch FPU emulator trap to BREAK instruction
From: Muthu Kumaran <>
Date: Fri, 5 Feb 2010 08:05:07 +0000
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I am using 2.6.18 linux version on MIPS32 core. One of the application
is using intensive floating point operations. This hardware doesn't
have FPU and also the application is not compiled for software
floating point support.
Hence, it is using the floating point emulation.

While running that application, On a timer interrupt there is a normal
integer div instruction which gives wrong result in the HI register.

However, when I applied the following patch, this problem disappeared.

When I looked into the patch, handling of invalid instruction
exception is moved from trap to break.
There is no other behavioural change in this patch. I really don't
understand the need for this patch, May I ask someone to explain the
background information behind this patch? Is this for any known issue?

I am new to both Linux and also MIPS core.


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