SIMD under RedHat 6.1. Detailed step by step guide for the Linux
The PentiumIII has new machine instructions, SIMD or XMM that execute
faster than the old floating point instructions. These instructions
are much slower than the MMX instructions but in cases where 16 bit is not
enough they are the best alternative.
To use SIMD instructions it may be necessary to implement a
patch and recompile the kernel.
Linux 2.4.xx will probably have SIMD support included.
I am not an experienced Linux user.
It took me quite a while to find out that the procedure
given below works.
Going more directly failed for unknown reasons.
The below sequence seems fully reliable:
1. Boot from the RedHat 6.1 CD in graphical mode.
(text mode will not install X with a SiS 6326 board and a SyncMaster 570B)
2. Install Custom System and select "everything".
This is a standard RedHat installation. Very easy.
3. Boot from the hard disk.
4. Type: /usr/sbin/kbdconfig and select keyboard,
the initial setup does not work. (not with a SiS 6326 installed anyway)
5. Type: cd /usr/src/linux
6. Type: make mrproper
7. Type: make config
8. Type: make dep
9. Type: make bzImage
10. Type: make modules
11. Type: make modules_install
12. Type: cp /usr/src/linux-2.2.12/arch/i386/boot/bzImage /boot
13. Edit the file /etc/lilo.conf
Change the line: image=/boot/vmlinuz-2.2.12-20
14. Type: lilo
15. press ctrl+alt+delete to reboot.
16. Go to the /usr/src/linux directory and copy
jimb.linux-2.2.12-sse-ptrace-2.patch to it (see below).
17. Type: patch -p0 < jimb.linux-2.2.12-sse-ptrace-2.patch
18. Type: make config Do not change anything but:
a) "Processor family" from 386 to PIII,
b) "Enable PII/PIII Extended/Fast FPU save and restore" from N to Y,
c) "Enable PIII Streaming XMM operations" from N to Y and
19. Type: make dep
20. Type: make bzImage
21. Type: make modules
22. Type: make modules_install
23. Type: cp /usr/src/linux-2.2.12/arch/i386/boot/bzImage /boot
answer y to overwrite the previous boot image.
24. Type: lilo
25. Press ctrl+alt+delete to reboot.
There will be unresolved symbols but they are harmless (on my system)
The jimb.linux-2.2.12-sse-ptrace-2.patch file
is due to Jim Blandy. Check the link for more information
about this patch and about SIMD in general.
You may get compressed versions of the patch here:
simd.bz2 packed with bzip2 (14 kilobytes) or
simd.gz packed with gzip (15 kilobytes).