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Description of the Ios.log File

This article was previously published under Q138899
SUMMARY
The Ios.log file is created by the I/O Supervisor (IOS) as it attempts todetermine whether or not it can safely install 32-bit drivers. Windowscreates an IOS.LOG file in the Windows directory if any drives are usingMS-DOS Compatibility mode.This usually means that the Dosdrv.sys or Pcidrv.sys driver is in theConfig.sys file, probably as a driver for a Promise Technologies cachingcontroller, but the corresponding 32-bit FastDisk driver is not loaded.

This message is often caused by device drivers and TSRs that create diskdrives that do not correspond to physical devices. The MicrosoftInterlnk program is one example.

The specified device driver or TSR hooks INT 13 and is not on theIos.ini list of safe TSRs and drivers.

The specified device driver requires that all disk access be routedthrough it. After the request has passed through the device driver, therequest it is submitted to the 32-bit driver. However, there is aperformance penalty due to this extra routing.

This problem is typically caused by EZ-Drive software versions 3.6 andearlier.

This typically means that your computer has been infected by a boot-sector virus. It may also be caused by real-mode geometry translationsoftware for IDE hard disks with more than 1024 cylinders.

The "Details" section may provide clues as to which of the twosituations is the more likely case.To resolve this message, obtain the appropriate 32-bit FastDisk driver,copy it to the Windows\System folder, and then add the followingstatement to the [386Enh] section of the System.ini file:
   device=<driver>.386				

Error issuing int 25h: unit nn, error nn



IOS performed an INT 25h (disk read) request to determine which physicaldevice is associated with unit number nn, but the device driver returnedan error code. Furthermore, the specified driver does not have the"non_disk" attribute in the Ios.ini file.

Possible error codes include:
   80   device failed to respond (timeout)   40   seek operation failed   20   controller failed   10   data error (bad CRC)   08   DMA failure   04   sector not found   02   bad address mark   01   bad command				
CAUSE:

This message is often caused by device drivers and TSR's that create disk drives that donot correspond to physical devices. The Microsoft Interlnk program is ne example.

Resolution:

Remove any device drivers and TSRs that provide "phantom" disk drives,or add them to the Ios.ini file as "non_disk" drivers.

Unsafe driver xxxxxxxx controlling unit nn



IOS has determined that the indicated device driver is unsafe due to theway it manages unit nn.

Resolution:

Remove the indicated device driver from the Config.sys and Autoexec.bat files.

Monolithic driver xxxxxxxx controlling unit nn



IOS is unable to communicate with the indicated device driver in orderto take over its functionality because the device driver does notsupport ASPI or CAM or INT 13. Furthermore, the specified driver doesnot have the "monolithic" attribute in the Ios.ini file.

Resolution:

Remove the indicated device driver from the Config.sys and Autoexec.bat files.

Unsafe CD-ROM driver, xxxxxxxx, disabling protect mode CDROM



The specified CD-ROM driver was found in the [CDUnsafe] section of theIos.ini file.

Resolution:

Remove the indicated device driver from the Config.sys and Autoexec.batfiles.

Too many TSRs are hooking INT 13 & h/w interrupts.



There are too many device drivers and TSRs in the Config.sys andAutoexec.bat files that hook INT 13. The maximum number of TSRs anddevice drivers that can hook INT 13 without forcing MS-DOS Compatibilitymode is 20.

Resolution:

Reduce the number of device drivers and TSRs in the Config.sys andAutoexec.bat files.

UnKnown int 13 hooker xxxxxxxx



NOTE: This section does not apply if the name of the INT 13 hooker is"MBRINT13." See the "Unknown INT 13 hooker MBRINT13" section.

IOS cannot use 32-bit disk access due to the presence of the indicateddevice driver or TSR.

Remove the indicated device driver from the Config.sys and Autoexec.bat files.

DO_NOT_CARE+MUST_CHAIN INT 13 qualified combination
Using RMM for all logical drives. Can still load Port Drivers



IOS must load the real-mode mapper (RMM) because there is a devicedriver listed in the Ios.ini file with the "must_chain" attribute.

Look in the Ios.ini file for drivers marked "must_chain" and see if anyof them appear in Config.sys or Autoexec.bat. Remove all such drivers.

Illegal int 13 Qualifier combination. Punt Port Drivers



IOS has found a device driver listed in the Ios.ini file as"must_chain," and another device driver listed in the Ios.ini file as"must_not_chain." These two requirements are contradictory.

Resolution:

Look in the Ios.ini file for drivers marked "must_chain" and"must_not_chain" and see if any of them appear in Config.sys orAutoexec.bat. Remove all such drivers.

Downrev version of IDE software controlling too many int 13 drives



IOS has determined that the IDE software controlling the hard diskcannot safely be taken over because it is controlling drives on thesecondary IDE controller.

Cause:

For information about how to resolve this problem, please see thefollowing article in the Microsoft Knowledge Base:
ARTICLE-ID: 126855
TITLE : Windows 95 Support for Large IDE Hard Disks

Unsafe driver xxxxxxxx hooking the foll. logical units.
unit number: nn
unit number: nn



IOS did not find the indicated driver in the Ios.ini file as a "safe" driver.

Resolution

Remove the specified device driver or TSR from the Config.sys andAutoexec.bat files.

Punting miniports because of unknown CAM driver xxxxxxxx



IOS has found a device driver that uses CAM that is not listed in theIos.ini file as a safe driver.

Resolution:

Remove the specified driver from the Config.sys and Autoexec.bat files.

Punting miniports because of two identical peripherals



IOS has found two ASPI/CAM device drivers that are both managing thesame SCSI device. IOS is therefore unable to determine which of the twodevice drivers to use.

Resolution:

Remove the device driver you do not need.

CAM driver loaded from AUTOEXEC.BAT or later



A CAM driver has been loaded from a location other than the Config.sysfile. IOS cannot take over such drivers.

Resolution:

Isolate the driver and remove it.

ASPI driver loaded from AUTOEXEC.BAT or later



An ASPI driver has been loaded from a location other than the Config.sysfile. IOS cannot take over such drivers.

Resolution:

Isolate the driver and remove it.

UnKnown int 13 hooker MBRINT13



This means there is an unrecognized INT 13h hook in the master bootrecord (MBR).

Resolution:

Perform a virus scan on your computer to make sure your computer is notinfected.

For information about how to determine whether the problem is in thegeometry translation software and how to upgrade to a version that iscompatible with Windows 95, please see the following article in theMicrosoft Knowledge Base:
ARTICLE-ID: 126855
TITLE : Windows 95 Support for Large IDE Hard Disks

PART 2

The next section of the Ios.log file summarizes all the drives that areusing the real-mode mapper (RMM) for disk access. This section maycontain no lines, one line, or more than one copy of the following line:
Unit number nn going through real mode drivers.

This line is repeated once for each unit that is using the real-modemapper.

PART 3 - THE CONFIG.SYS FILE DETAILS

This section of the Ios.log file provides a listing of each devicedriver loaded in the Config.sys file.

Each driver is listed in the following form:
Driver Name: <FileName>
      Character Driver      Block Driver controlling nn unit(s)      Driver Info:         Driver Address: xxxxxxxx         INT 13 Hook: xxxxxxxx         IOSYS INT 13: xxxxxxxx         INT 4B Hook: xxxxxxxx         INT 4F Hook: xxxxxxxx         ASPI Entry: xxxxxxxx         Hooks the Foll. logical units (0=A,...):            Hooks: unit number: nn            Hooks: unit number: nn      Config.sys line number:  nnnnnnnn      Config.sys date/time stamp:  xxxxxxxx      Hardware interrupt hook map:  xxxxxxxx				

Not all lines are listed for all devices.

Character Driver vs. Block Driver

The lines "Character Driver" and "Block Driver controlling nn unit(s)"are mutually exclusive.

Driver Address

The 8-character address encodes the 16:16 segment:offset location of thedriver in memory.

INT 13 Hook

The 8-character address encodes the 16:16 segment:offset location of thedriver's INT 13 hook.

IOSYS INT 13

The 8-character address encodes the 16:16 segment:offset location of theINT 13h vector at the time Io.sys was loaded. This value is displayedonly for the Io.sys driver itself.

INT 4B Hook

The 8-character address encodes the 16:16 segment:offset location of thedriver's INT 4B hook.

INT 4F Hook

The 8-character address encodes the 16:16 segment:offset location of thedriver's INT 4F hook.

ASPI Entry

The 8-character address encodes the 16:16 segment:offset location of thedriver's ASPI entry point.

Hooks the Foll. logical units

Lists the logical units that the device driver has hooked.

Config.sys line number

The line number in Config.sys from which the device driver was loaded.The value is displayed in hexadecimal. If the device driver was loadedimplicitly, then line number 00000000 is displayed.

Config.sys date/time stamp

The date/time of the Config.sys file, in encoded hexadecimal format.Decoding this value is not generally important.

Hardware interrupt hook map

A bitmask of hardware interrupts hooked by the device driver, encoded inhexadecimal. The lowest bit corresponds to IRQ 0, and so on.

An entry for a fake device named Mbrint13.sys is generated if the masterboot record has been hooked. The INT 13 Hook address is the address ofthe hook as installed by the MBR. If this value begins with a 9, then itis likely that the computer has been infected by a boot-sector virus.

PART 4 - THE AUTOEXEC.BAT FILE DETAILS

The final section in the Ios.log file is a listing of TSR programsloaded by the Autoexec.bat file. This section is headed by the line:
Autoexec Date/Time Stamp: xxxxxxxx

Decoding the date/time stamp is not generally important.

Each TSR is listed in the following form, with only applicable lineslisted for each TSR.
TSR Name: xxxxxxxx
      Autoexec Position: xxxxxxxx      Hardware Interrupt Hook Bit Map: xxxxxxxx         Hooks: INT 13         Hooks: unit number: nn         Hooks: unit number: nn				

Autoexec Position

The file offset within the Autoexec.bat file of the line that caused theTSR to be loaded.

Hardware Interrupt Hook Bit Map

A bitmask of hardware interrupts hooked by the TSR, encoded inhexadecimal. The lowest bit corresponds to IRQ 0, and so on.

Hooks: INT 13

The TSR hooks INT 13 and is a strong candidate for forcing the system touse compatibility-mode disk access.

Hooks: unit number: nn

Lists the logical units that the TSR has hooked.
MORE INFORMATION
The Ios.log file has several sections, each of which is described below.

GLOSSARY OF TERMS

INT 13 - Interrupt 13 is the hard disk drive interrupt. When theoperating system needs to access the hard disk, it issues an INT 13call. This typically is serviced by the BIOS, but device drivers andTSRs may intercept the request.

INT 4B - Interrupt 4B is the interrupt used by Common Access Method(CAM) versions 1.9 and earlier.

INT 4F - Interrupt 4F is the interrupt used by Common Access Method(CAM) versions 2.0 and later.

Hook - Hook is a synonym for "intercept." For example, an "INT 13hooker" is a device driver or program that intercepts all INT 13 calls.The reasons for doing so may be innocuous (a screen saver), beneficial(a device driver that enables you to access a device that otherwisewould be inaccessible), or harmful (a virus).

TSR - (Terminate and Stay Resident) - A program, typically loaded inthe Autoexec.bat file, that loads itself permanently into memory.

Unit number - A unit number is a drive letter converted to a number.Drive A is unit number zero, drive B is unit number one, and so on.These are sometimes referred to as "logical units," which should not beconfused with SCSI logical unit numbers (LUNs).

PART 1

The first section of the Ios.log file summarizes IOS takeover. Thissection may contain none, one, or more of the lines listed below in theorder in which they normally appear.


Incompatible driver xxxxxxxx. Load FastDisk for driver if possible



The indicated device driver hooks INT 13 in a manner that Windows hasconsidered unsafe, but which would become safe if a Windows 3.1 FastDiskdriver were installed.

REFERENCES
"Microsoft Windows 95 Resource Kit," Chapter 19
Properties

Article ID: 138899 - Last Review: 01/19/2007 15:35:31 - Revision: 1.2

  • Microsoft Windows 95
  • Microsoft Windows 98 Standard Edition
  • kbinfo KB138899
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