schmitz@fas.ri.cmu.edu (Donald Schmitz) (08/18/89)
This is not properly a real-time question, but it seems many readers are doing similar things, and I am getting desprate looking for an answer. We have developed our own real-time environment similar to VxWorks for a SUN3 host. The device driver works fine with 1 4M CPU, but when we add the 2nd one the SUN dies in mysterious ways - like in mount, or vi, or SunTools. This only happens when the 2nd CPU is configured in the kernel, the system works fine with the 2nd CPU installed but not configured, suggesting it is not a hardware problem. Changing the amount of device memory changes where the machine dies, suggesting kernel program memory is being overwritten. We have played around changing the amount of memory the driver thinks the CPUs occupy, it seems like the problems start when there is more than 8M of device memory mapped into the kernel. This makes us suspicious, since 8M is 1K of (8K) pages, suggesting it is an undocumented limit in the SUN MMU hardware or software. However, VxWorks can reportedly support multiple CPUs, many of which have 4M or more of memory, and it seems likely people doing vision or graphics work would have more than 8M of frame memory. So the questions are, does anyone have a SUN3 with more than 8M of devices installed, and if so is there any special magic to make it work? I'll summarize any email responses I get back to the net. Don Schmitz schmitz@fas.ri.cmu.edu Work phone: 412-268-7658