Kernel Summit: Virtual Memory
Posted Jul 30, 2004 15:29 UTC (Fri) by metalwheaties
Parent article: Kernel Summit: Virtual Memory
It is actually true that nearly EVERY system already has hardware remapping of memory on precisely the right granularity required for memory hot removal. It's the same mechanism the BIOS/boot firmware uses to map the DRAM contiguously in the first place. The memory controller must be told at boot time how much DRAM is associated with each chip select and to what physical address this chip select should respond. Changing these values while the memory controller is in use is possible - at least for the memory controllers I am familiar with.
Unfortunately, some CPU architectures have traditionally been closed with regard to these registers and their usage. Now AMD has opened up with Opteron. Only the Intel chipset world remains closed. If Intel compatible the "chip set" manufacturers would open up their dirty little secrets and tell people how to program these registers without the double-secret-probation handshake they have with the small group of elite BIOS vendors, these problems would be easily solved by the smart people in the Linux community.
By the way, none of the other CPU architectures have EVER suffered from this secrecy problem, AFAIK.
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