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Chapter 9 - Optimising the Windows kernel

This chapter describes changes to the Windows kernel. Improvements are significant but the changes are low-level and must be made with care. They are performed by adding ‘switches’ to Boot.ini, a file hidden in the system’s root directory (typically C:\) which instructs Windows how to load.

In Explorer, select Tools > Folder Options > View. Check Show Hidden files and folders and deselect Hide protected operating system files (Recommended). Click OK twice.

The c:\boot.ini file is now visible: right-click on it, select Properties and deselect Read only.

Make a backup copy and open the original in Notepad. Here's a sample of boot.ini:

[boot loader]
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windows XP Professional" /fastdetect /NoExecute=OptIn

Changes are made to the command line (the last line as above). Restart Windows and test after each change – do not apply them all at once. Finally, restore the file’s read-only property and Explorer’s View mode.

Step 1 – disable ‘noexecute’

The switch usually reads "/noexecute=optin". Change it to "/noexecute=alwaysoff" to disable Windows’ Data Execution Protection. It works best when Execute Disable Bit in the BIOS is disabled.

Step 2 – set ‘timeres’

Add "/timeres=9800". Windows has four timing resolutions for ‘waitable timers’ ranging from 0.98 ms to the default of 7.8 ms. The lowest value is set here. The setting only affects multi-processor systems (the recommended Intel E7200 has two) and has no effect on single-processor systems.

Step 3 – disable the kernel debugger

Add "/nodebug" to disable kernel-mode debugging.

Step 4 – set ‘pcilock’

Add "/pcilock". Setting PCI lock stops Windows dynamically assigning IO/IRQ resources to PCI devices, leaving them to be configured by the BIOS. The following proviso can be ignored with the Gigabyte motherboard.

  1. Ensure that PnP/PCI Configurations > PNP OS Installed is set to No in the BIOS otherwise Windows becomes unstable.
  2. Do not make the change if the BIOS does not offer the setting or on Dell PCs, where it disables keyboard and mouse functions.

Step 5 - final check

Once all the changes have been implemented, the command line should read:

...WINDOWS="Microsoft Windows XP Professional" /noexecute=alwaysoff /fastdetect /timeres=9800 /nodebug /pcilock

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Page last modified on August 28, 2009, at 11:24 PM