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SubjectRe: Linux and physical memory


On Sun, 17 Jan 1999, christophe leroy wrote:

> When a task jumps into kernel code, CS is 0x10
> When a task is in user mode, CS is 0x23.
> It means that it is already two separate 4Gbytes capable spaces.

Sorry, but you are confusing segments and paging. Segments give you
windows into the *same* linear space. 4G. Paged. Segments don't add a
thing to memory mapping. Yes, it sounds cool - tons of virtual address
space. Not. Unless you are playing with 36-bit space all you can get is a
window into 4G linear address space. To change the mapping you'll need to
flush TLB - it works below segments.
[snip]

> In 386 also: 64Tera bytes address space, 4Gbytes phys space
... and 4G linear space between them. Which kinda kills the whole
idea.


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