3 ms·
Not only that, but the linearity of physical ram is a fiction as well: in nearly all systems these days ram is made up of multiple memory modules (the MM in SI
by philsnow 12y ago
Not only that, but the linearity of physical ram is a fiction as well: in nearly all systems these days ram is made up of multiple memory modules (the MM in SIMM/DIMM), and to my knowledge, the OS is free to stitch them together in any way it sees fit.
(All of this is to say nothing of NUMA.)
However, one of the responsibilities of the OS is to hide all that messy detail from the bare-metal programmer or compiler writer and provide a simple(r) abstraction over the hardware. Thus, "(physical) memory is a big array".
- dfox 12y agoOn PC, BIOS configures memory controller in such way as to hide boundaries of memory modules from OS. Resulting address space still contains some holes and stuff that is not physical memory, but OS gets map of this from BIOS. Originally (on systems with 36pin SIMMs) this wasn't the case and you had to match memory modules such that they produce continuous block of addresses. In essence the situation is pretty much same as for user space program: you get big address space and list of memory regions that are mapped and usable.