## Display Device Driver Reference for OS/2

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### Device Detection

Device detection is built into both SCREENx.SYS PDD and SVGA(OEM).EXE. SVGA (OEM).EXE does not need to have device detection added if the generic .PMI file is sufficient. However, as a courtesy to the customer running the drivers and a safeguard against running inappropriate drivers, some device detection should be built into either or both of the modules.

SCREENx.SYS PDD does not have to be modified to add device detection, unless the vendor wishes to use the default .DSC file-selection feature of the display driver installation utility. SVGADEFS.H contains _ADAPTER IDs that are reserved for vendor use for this purpose. For vendors who would like to have a new _ADAPTER ID allocated, a call to DUDE with the request and the name of the vendor is required. When adding device detection to SCREENx.SYS PDD, the allocated ID should be returned. Detection function IdentifySVGA in svgaid.asm is common to both SCREENx.SYS and SVGAOEM.EXE ( SVGA.EXE), with the exception that the PCI detection is invoked only in the PDD, not in the utility. The PCI interface, as used by the SCREENx.SYS, is exported by the OS/2 loader's OEMHLP PDD. Its full interface is documented in inc\pci.inc and samples PCITEST.C and PCITEST.H in src\oempmi. As code is added to SVGAID.ASM, it should be propagated to both SVGA.EXE and SCREENx.SYS PDD. The makefiles will take care of conditional compilation for both modules.