Messages in this thread | | | Date | Thu, 21 Jun 2007 18:46:02 -0700 | From | "H. Peter Anvin" <> | Subject | Re: how to tell linux (on x86) to ignore 1M or memory |
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Rene Herman wrote: > On 04/19/2007 04:18 PM, Bart Trojanowski wrote: > >> I need to preserve some state from the bios before entering protected >> mode. For now I want to copy it into some ram accessible by >> real-mode, say the last megabyte visible in real-mode. >> >> What's the easiest way to have linux ignore the megabyte starting at 15M? > > Note that real-mode can only access the first megabyte (*) and not the > first 16. 16MB is the 16-bit protected mode (286) limit. >
No, 16-bit protected mode (on 386+) is not limited to 16 MB.
The main reason there is a 16 MB limit in some current systems is that ISA, and the ISA DMA controller only had 24 address lines.
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