Support for the standard IBM VGA chip (and compatibles) is provided by the XF86_Mono, XF86_VGA16 and XF86_SVGA servers with the generic driver.
Support for the IBM 8514/A chip (and compatibles) is provided by the XF86_8514 server.
Support for the IBM XGA-2 chip is provided by the XF86_AGX server.
Support for the standard IBM VGA chip (and compatibles) is provided by the "vga" driver.
There is no support for the IBM 8514/A or XGA-2 because the drivers have not been ported.
The standard VGA core is supported in both versions, but there is no support for the 8514/A or XGA-2 in 4.0.