Den 2023-03-23 kl. 18:51, skrev Johnny Billquist:
Yep, and that is what we do :-) The only problem is that there is no limit check so we grab a little too much (since 512MB of memory is by some magnitude more than I could even think when this code was written almost 30 years ago...).On 2023-03-23 18:31, Anders Magnusson wrote:Den 2023-03-23 kl. 18:14, skrev Mouse:Yep, but that is not possible, since ~everything is possible to change dynamically and we cannot expand the SPT on-demand since it is located in physical memory. Having a SPT that can map all of S0 virtual memory would take 8MB of physical memory, which were too much of the available memory back when I wrote that code. Maybe it isn't today when things are mostly run in simh and a different strategy should be used?Another way would be to limit the physical memory to 256M and add support to not map all of physical memory for large-memory machines as a compile-time option.I'd say the rightest thing to do is compute - either mechanically or by hand - what amount of physical memory would put SLR as close as possible to 200000 without going over, then cap physical memory size at that value (preferably with a message).If we actually have 512M of physical memory, then I don't see the problem of letting the page table grab 8M of it.
But we need to set this up dynamically, but I thought we already did?
Yep, we do.Maybe it would be enough to just limit the space to full S0? We cannot expand it further anyway...
-- Ragge