On 2023-03-07 19:00, Dave McGuire wrote:
On 3/7/23 12:55, Anders Magnusson wrote:The P0/P1/S0/S1 space is in virtual space.The 512M is physical memory. Physical address space is a total of just 1G, with half dedicated to memory, and half to I/O space.So 512M is the absolute maximum the machines can have. And there is some problem with this in NetBSD.This must be model-specific, somehow?The I/O space starts at 512MB.Yes, ah, so memory must be discontiguous in some machines. The VAX-7000 at LSSM has 1.5GB of RAM. I hadn't thought about how that would work until this thread.
The 7000 is an NVAX. As mentioned, it can do two different formats for the PTE. When you go for the new format, I am not sure if the I/O area is also placed somehow differently. It's been quite a while since I looked at this on the 7000.
But basically, only NVAX machines can even theoretically have this, and I'm not sure than any other than the 7000 actually did it.
The 7000 shares the bus, memory and peripherals with the Alpha 7000.
Johnny
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