(C) 2021 - 2024, Eric Voirin (oerg866)
K6INIT is a driver for MS-DOS that lets you configure special features of AMD K6-2/2+/3/3+ processors, replacing tools like k6dos.sys and setk6.exe, and is similar to FASTVID on Pentium systems.
While K6INIT can run completely autonomously, it supports manual, detailed control over Memory Type Range Registers (including Write-Combine and Cachability modes), Write Allocate, Write Ordering, CPU Cache and Frequency Multiplier.
In contrast to other tools, K6INIT can be loaded from CONFIG.SYS, so it works
even with an extended memory manager (such as EMM386) installed.
If called with the /auto parameter, K6INIT does the following:
- Write Ordering mode to 1 (All except UC/WC)
- Write Allocate for all system memory (auto detected)
- Write Combining for Linear Frame Buffer(s) exposed by PCI/AGP graphics cards and VESA BIOS (auto detected)
- L1 Cache to Enabled
- L2 Cache to Enabled (supported CPUs only!)
- Data Prefetch to Enabled
This can be altered and overridden with many command line parameters.
K6INIT runs on Chomper Extended (CXT) K6-2 chips or later.
K6INIT was built using the LIB866D DOS Real-Mode Software Development Library
- Detect CPU type automatically
- Detect total available system memory (Using E820 and E801 methods)
- Detect 15-16M Memory hole automatically
- Give precise control over Memory Type Range Registers (MTRRs) including Write-Combine and Uncacheable modes.
- Set MTRR to enable Write combining for PCI/AGP BAR Frame Buffers automatically
- Set MTRR to enable Write combining for Linear Frame Buffers (LFBs) automatically (requires graphics card with VESA BIOS extensions)
- Set Write allocate for system memory
- Set Write Order mode
- Set Frequency Multiplier (K6-2+/III+ only)
- Enable/Disable L1 Cache
- Enable/Disable L2 Cache (K6-2+/K6-III/K6-III+ only)
- Enable/Disable Data Prefetch
- List all PCI/AGP device Base Address Regions (BARs)
| CPU Type | Family | Model | Stepping |
|---|---|---|---|
| AMD K6-2 (CXT Core) | 5 | 8 | C |
| AMD K6-III | 5 | 9 | Any |
| AMD K6-2+ / AMD K6-III+ | 5 | D | Any |
- Supported AMD K6 family CPU (see above)
- Microsoft MS-DOS 5.0 (or compatible) or higher
- Microsoft Windows 95/98 support
- FreeDOS support
- Other systems such as DR-DOS untested, but should work.
Usage (config.sys):
DEVICE=K6INIT.EXE <parameters>
Usage (command line):
K6INIT.EXE <parameters>
All parameters are case-inensitive. Parameters other than /auto should only be used by knowledgeable users.
K6INIT offers several command-line options to configure and manage memory settings, CPU features, and other system parameters. Below is a detailed explanation of each parameter.
Description: Prints this list of parameters.
Description: Displays the current program status.
Description: Fully automated setup.
Description: Enables Write Combining for a specific memory range. Parameters:
offset: Linear offset (e.g.,0xE0000000)size: Length in kilobytes (e.g.,8192)wc: Write-combine flag (1to enable,0to disable)uc: Uncacheable flag (1to enable,0to disable)
Notes:
- The
/mtrroption can be used twice. - Discards any MTRRs configured before running the program.
Description: Automatically finds and enables Write Combining for the Linear Frame Buffers (LFB).
Description: Automatically finds and enables Write Combining for Frame Buffers exposed by PCI / AGP graphics cards (experimental).
Description: Enables Write Combining for the VGA memory region (A0000-BFFFF).
Notes:
- Warning: This option is potentially unsafe. Do not use this memory region for Upper Memory Blocks (UMBs).
- Equivalent to:
/wc:0xA0000,128,1,0
Description: Disables Memory Type Range Registers (MTRRs) entirely.
Notes:
- Clears any existing MTRRs, including Write-Combined and Uncacheable regions.
Description: Configures Write Allocate (WA) settings.
Arguments:
size: Memory size in kilobytes.
Notes:
- Set this to
0to disable Write Allocate.
Description: Forces 15-16 MB memory hole skipping for Write Allocate.
Notes:
- K6INIT detects the memory hole automatically, but this option can be used to force it.
Description: Configures the Write Order Mode.
Arguments:
mode: A single digit representing the desired mode.0: All memory regions (Slow)1: All except uncacheable or write-combined regions (Fast)2: No memory regions (Fastest)
Description: Configures the CPU frequency multiplier.
Arguments:
x: Integral part of the multiplier.y: Fractional part of the multiplier.
Notes:
- Requires a K6-2+ or K6-III+ CPU.
- Example usage:
/multi:5.5
Description: Enables (1) or disables (0) the Level 1 cache.
Description: Enables (1) or disables (0) the Level 2 cache.
Notes:
- Only K6-2+ and K6-III+ CPUs have an on-die L2 cache.
Description: Enables (1) or disables (0) Data Prefetching (DPE)
Description: Lists all Base Address Regions (BARs) exposed by PCI/AGP devices in the system.
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MS-DOS 6.xx or 7.xx or Windows 95/98
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Microsoft C / C++ Compiler Version 7.00
-
latest patch set required
-
Also works with Microsoft Visual C++ 1.52. This is not recommended because it is not really meant for pure DOS development.
In this case you need a 32-Bit DOS Extender such as HX-DOS. The DOSXNT that is included doesn't play nice with my machine sadly.
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LIBandINCLUDEdirectories from the DOS Internals disk bundled with Geoff Chappell's excellent book of the same name Can be acquired here: https://www.pcjs.org/software/pcx86/sw/books/dos_internals/I have requested permission from Geoff Chappell to bundle these files with the K6INIT repository, but have not yet received a response.
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Updates for the above libraries from Geoff Chappell's website: https://www.geoffchappell.com/notes/dos/internals/crtdrvr/update.htm?ta=8.714286804199219&tx=6
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DPMI host (not necessary on Windows)
- I use HXDPMI32 (part of HXDOS by Japheth).
Note: Previous versions required the Microsoft Macro Assembler to build. As LIB866D includes macros that allow the usage of unsupported opcodes in inline assembly, this is no longer the case.
cd <somewhere>\k6init
nmake
That's all.
To make a build with a lot of verbose debug output, build it with DEBUG=1:
nmake DEBUG=1
While Borland C/C++ 3.x, Borland Turbo C/C++ 3.0 and OpenWatcom v2 are technically supported, the resulting executable will not be loadable in CONFIG.SYS. Use the following commands to compile them:
tcc -wall -g1 -Ilib866d -ek6init.exe lib866d\*.c k6init.c
bcc -wall -g1 -Ilib866d -ek6init.exe lib866d\*.c k6init.c
wcl -wcd111 -w9 -bt=dos -Ilib866d lib866d\*.c k6init.c
I developed this on an AMD K6-II CXT 500MHz. DOS is not the most stable and easy to configure environment in the world and there are a few quirks to address.
USE HIMEM.SYS THAT COMES WITH MICROSOFT C/C++ 7.00!
You'll get weird errors otherwise. It's something to do with XMS size. I can get this to compile with JemmEx when limiting its reported size to 32MiB.
QEMM '97 also works, but after a while I got really strange behavior. I cannot open K6init.h (and only that file) properly via network share anymore.
I couldn't really fix this, so I took the linker (LINK.EXE and CVPACK.EXE) from Microsoft Visual C++ 1.52. NOTE: The linker from VC1.52 requires a 32-Bit DOS Extender.
VC1.52 includes one in the form of DOSXNT.EXE
No idea. I don't use the debugger (yet) so at the moment it is not a big deal for me but it would be cool to fix this...?
Because when I load it, it reboots my computer. %-)
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