## Graphics Adapter Device Driver Reference

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### PMIREQUEST_SOFTWAREINT - Remarks

This API allows for real-mode BIOS calls that need up to 4 KB in one or two input or output buffers. Although the service is generic, only VIDEO BIOS has been tested.

There are two types of worker VDM processes, depending on the requested VDM initialization as well as on the level of VDM support installed on the target machine, as follows:

1.Full VDM.

This process is equivalent to a full-screen DOS session that is created via an icon, stripped of its OS/2 components. The session has unrestricted video access. The session's DOS settings are manipulated by the VIDEOPMI and, therefore, are not affected by any standard settings or modifications to any of the DOS icons. The session can never be given foreground focus and is terminated only after its parent process terminates. If that should occur, there are no limitations on creating a new worker process. However, because the shell is the parent process, the event is unlikely. The session is completely hidden, as it is created without the knowledge of the session manager.

Note: When the int 10 full VDM session is started, the system will attempt to execute a videopmi.bat file. If the system does not find a videopmi.bat file in the root directory, it will default to autoexec.bat.

Because users often customize the autoexec.bat file, the autoexec.bat is unreliable or unusable in the int 10 full VDM session. To be sure the system has full control of the run-time environment of that session, make sure a videopmi.bat file exists in the system root directory.

Attention: LIMITATION

a.The full-VDM process can be created only under the shell process. VIDEOPMI ensures that the creation is limited to this window. A kernel patch is needed to cover any situations in which this may not be acceptable , for example, running a custom shell or testing the base video without a shell.

b.Full VDM requires that DOS support be installed on the target machine. As a result, a vendor driver using the software interface must ensure that this information is relayed to the customer. If, for any reason, DOS support is not desirable, full VDM is not the appropriate software interrupt solution and the Mini-VDM process described below should be used.

To ensure that a full-VDM process is created, the caller that initializes the VDM environment must specify the pIn parameter. Specifying the pIn-> ulFlags = VDM_INITIALIZE is sufficient. Optional application name and parameters may be specified as well. When initializing, if VDM creation fails, one of the following errors is returned:

ERROR_INADEQUATE_VDM_SUPPORT Make sure vprpmi.sys is installed.

ERROR_FULLVDM_CREATION_NOT_SHELLPROCESS The limitation listed under 1.a. ( above) applies.

ERROR_MINIVDM_PROCESSUPPORT_ONLY Make sure vprpmi.sys is installed. Mini- VDM is available, so subsequent requests may be successful.

2.Mini VDM

This type of VDM process is provided for customer situations in which installing DOS support or running a full-VDM process is unacceptable. A mini-VDM process is a minimal v86 process for which ROM BIOS, BIOS data area, and video aperture are mapped in. All of the same calling interfaces and buffer passing capabilities of the full VDM apply. The worker VDM is created by the kernel as a child of the root process and, as such, is indestructable. If the video subsystem that created the process is unloaded and reloaded, the same VDM process is used.

Attention: LIMITATION

a.Virtualization of hardware resources and the exception management of mini-VDM are virtually nonexistent. All of the I/O resources are mapped physical, so any I/O that is executed goes to the hardware. None of the hardware interrupts are reflected; for example, timer ticks are not reflected in the BIOS data area. All of the ROM areas are mapped physical, so any self-modifying BIOS (those that are not in true ROM, of course) will affect subsequently started VDMs. The BIOS data area is the only page that is mapped linear, which means that it can be garbled without any danger to other VDMs running in the system.

There is no exception management. As a result, any of the unmapped memory ( from 4 KB up to 0x9FFFF) or above 1 MB that is touched will cause a kernel exception to occur (no recovery). Neither virtual drivers nor the DOS kernel is loaded in this process, so no TSRs or utilities can be executed.

b.This solution requires a kernel patch for OS/2 Warp, Version 3.x customers, and a kernel patch and DOSCALLS.DLL upgrade for OS/2 2.x customers, in addition to the base video files.