This file serves as a flag to tell OS/2 whether SVGA support has been enabled with SVGA ON. The file actually contains data on
1. What video chipset your SVGA card has.
2. What SVGA modes, from the supported list, your adapter is capable of setting.
The list of supported modes is:
a. 640x480/256 b. 800x600/16 c. 800x600/256 d. 1024x768/16 e. 1024x768/256 f. 132x25 text g. 132x43 or 44 text
3. What values are in the video registers when the card is in each mode.. this data is used by OS/2 to save and restore the registers to their proper state when switching between sessions with different SVGA modes set.
This data file must be generated by typing SVGA ON from a DOS fullscreen session, because what SVGA ON actually does is set all the possible modes using the video card's BIOS and then read out the values of the registers into the .PMI file. If SVGA ON is run from a DOS window, OS/2's video virtualization takes over, and the BIOS doesn't set the SVGA modes properly.
Related Issues with this File
During startup, when the base video handler initializes, the SVGADATA.PMI file is opened and parsed. If there is no SVGADATA.PMI file or it contains unexpected or invalid information for the chipset, the video PMI (protected mode interface) dynamic link library is unlinked. Then, when the PM (presentation manager) driver attempts to set the video mode (to bring up the Desktop), it finds the video PMI unlinked and attempts to make the call to reload it. This is an unauthorized call and causes a trap in the kernel. The end result is an exception in the PMDD.SYS device driver with: SINGLEQ$ at CS:EIP=0950:00000971. The same process can occur for other device drivers.