dms@mit-hermes.ARPA (David M. Siegel) (08/31/85)
Two related questions: We need to access the word registers of a home-brewed device on the CMI (main memory) bus of a VAX/750. How does one do this from the Kernel of 4.2 BSD Unix? Next, we want to map a large set of memory-like addresses that are part of this device directly into some users virtual address space. These addresses will respond exactly like VAX main memory, except that they should not be used by the operating system as memory. We want to allocate and deallocate them on command to different users. How does one do this? Ideally, we want a device driver that when opened will load some stuff into the device's registers, map the memory-like portion of the device to the user, and when closed, un-map the memory. I assume we must do this by frobbing the pte in some way. More specifically, the device registers are within the CMI IO space, somewhere above 0xf00000. The memory like area is below that address, but above the real memory arrays. Thanks! -Dave -- Arpa: dms@mit-hermes.arpa Usenet: mit-eddie!mit-hermes!dms