Linux FPU 440

Linux FPU 440

This page describes how to use the FPU with the Linux kernel on the Xilinx PowerPC 440 processor. The FPU is optional in the hardware such that many users don't have the FPU.

Kernel Configuration

The FPU needs to be enabled in the kernel configuration under the Platform support. Select the Enable Xilinx Soft FPU.


Minimal testing has been done. The kernel has been built with FPU and then booted with a root file system that was built for FPU.

FPU Commit

The FPU is now supported as we committed the following change.

Powerpc: Xilinx: Adding 440 FPU support

author John Linn <>
Thu, 2 Apr 2009 17:56:22 +0000 (11:56 -0600)
committer John Linn <>
Thu, 2 Apr 2009 18:24:40 +0000 (12:24 -0600)
commit 397877351c82ee66940c354595a9acf52f60cfb3
tree fb01a6452b2dcacdca7756ef4849fa72dcc022ee tree | snapshot
parent c7968c1312c9aad3273efc8aeffccc5a6cb7e244 commit | diff

Powerpc: Xilinx: Adding 440 FPU support

FPU support was in the code previously but removed when we took
the 440 code to the mainline kernel. This cleans up the previous
commits to have fewer kernel configs.

Signed-off-by: John Linn <>

arch/powerpc/kernel/entry_32.S diff | blob | history
arch/powerpc/kernel/fpu.S diff | blob | history
arch/powerpc/kernel/traps.c diff | blob | history
arch/powerpc/platforms/44x/Kconfig diff | blob | history

Previous History

This was discussed on the Embedded Linux forum on the Xilinx forums and here's a link to that thread.

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