Use SSE instructions on FreeBSD

Notice

This patch has already been marged to FreeBSD since 4.4-RELEASE.

What's New?

Wed Jun 20 17:25:02 JST 2001 / sys-r500-SSE-2.diff.gz: SSE support patch for FreeBSD 5.0-CURRNET (2001/06/20) is available.
Fri Mar 2 21:02:20 JST 2001 / sys-r500-SSE-1.diff.gz: SSE support patch for FreeBSD 5.0-CURRNET (2001/02/28) is available.
Wed May 17 00:07:40 GMT 2000 / sys-r400-SSE-5.diff.gz: Support mulitprocessor systems.
Submitted by Takekazu KATO <kato@chino.it.okayama-u.ac.jp>

Background

Intel ^® introduces some instructions to IA-32 processors, when they release Pentium ^® III processor, which is called SSE (Streaming SIMD Extensions.) These extensions are combined with a sigle instruction stream, multiple data stream (SIMD) model, which means we may operate multiple data at once. SSE may accelarate the performance of applications, especially using floating point operations.

To use SSE, we, at least, need an assembler that can handle SSE instructions, and some Operating System support as follows:

Set control register to enable SSE (Set bit 25 and 26 to 1 on %cr4).
Save and restore SSE registers, when OS switches process context.
Write an exception handler.

GNU binutils 2.10 supports SSE, but FreeBSD kernel has not supported SSE yet.

Patches

These patches provide basic support to use SSE instruction on FreeBSD box. They seem to work on both FreeBSD 4.0-RELEASE and FreeBSD 5.0-CURRENT (2001/02/28).

Paches for FreeBSD 5.0-CURRENT (2001/06/20) (build test only!)
- sys-r500-SSE-2.diff.gz
  MD5 (sys-r500-SSE-2.diff.gz) = 5c179a14e27e25324381dd271be7c95c
Paches for FreeBSD 5.0-CURRENT (2001/02/28)
- sys-r500-SSE-1.diff.gz
  MD5 (sys-r500-SSE-1.diff.gz) = 514558fc025d69b057bc2fc8ef97f64e
Paches for FreeBSD 4.0-RELEASE
- binutils-291-SSE.diff.gz
  MD5 (binutils-291-SSE.diff.gz) = 2bb9e36d724d1fbd66964a41597d32b0
- sys-r400-SSE-5.diff.gz
  MD5 (sys-r400-SSE-5.diff.gz) = de72e6f6bbdac76493bc536ca5c712d3

How to use it?

Rebuild GNU as to be able to handle SSE instructions.
Note: FreeBSD 4.0-RELEASE only. If you use FreeBSD 5.0-CURRENT, you must ignore this.
```
# cd /usr/src/contrib/binutils
# zcat /some/where/binutils-291-SSE.diff.gz | patch -p2
# cd /usr/src/gnu/usr.bin/binutils
# make install
	
```

Apply the patch to kernel source.

# cd /sys
# zcat /some/where/sys-rXXX-SSE-X.diff.gz | patch -p2

Add "options CPU_ENABLE_SSE" to your kernel configuration file, and rebuild kernel.

# cd /sys/i386/conf
# echo 'options CPU_ENABLE_SSE' > MYKERNEL
# config MYKERNEL
# cd ../../compile/MYKERNEL
# make depend; make

Install new kernel and reboot.

# make install
# sync ; sync ; sync
# shutdown -r now

Check hw.instruction_sse kernel variable. If it is 1, SSE instruction support is enabled on your kernel.
```
% sysctl hw.instruction_sse
hw.instruction_sse: 1
	
```

TODO

Exception handling.