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SubjectRe: using more than 2 GB as a ram disk
Date
Alexander Viro writes:
> On Wed, 3 Feb 1999, Albert D. Cahalan wrote:
>
>>>> Processes can have more than one segment, and 32-bit virtual address
>>>> spaces can themselves be made virtual. I suppose one could say that
>>>> the following hack uses segments to implement paging of a 36-bit
>>>> virtual address space.
>>>
>>> All segments map onto the same 4Gig virtual space
>>
>> I told you I was aware of that. Read the post again.
>> Hint: at any one point in time, most segments are invalid.
>> Another hint: the 4 kB pages need not be used at all.
>
> And you are going to do pagein/pageout by what chunks?

8 MB of course. :-)

Linux used to run on a 2 MB 386 with 4 kB pages. That would be

512 total pages
96 for the ISA hole
?? for the kernel itself

Maybe there were 350 pages. If you scale the page size up with the
new memory size and address space, you get close to 8 MB for a page.

The normal 4 kB pages could be used at the same time, but the huge
memory system is easier to explain if you forget about them.
You don't need 16 million puny little pages.

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