4GB memory limit

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CandyMan

Joined: 04 Sep 2009
Posts: 414
Location: film "CandyMan" directed through Bernard Rose OR Candy Shop

CandyMan 12 Dec 2011, 17:01

Whether it is possible to gain access to the memory above 4GB on 32-bit operating systems?
Any examples...

12 Dec 2011, 17:01

ManOfSteel

Joined: 02 Feb 2005
Posts: 1154

ManOfSteel 12 Dec 2011, 17:05

Yes, PAE.

12 Dec 2011, 17:05

egos

Joined: 10 Feb 2009
Posts: 144

egos 14 Dec 2011, 09:15

For 4 mb pages you can use PSE-36 mode if it's supported.
It is possible to use long mode paging structures for 32-bit OS.

14 Dec 2011, 09:15

smiddy

Joined: 31 Oct 2004
Posts: 557

smiddy 14 Dec 2011, 23:39

If you go to long mode, wouldn't you want to stay or run from long mode?

I will be struggling with this in the coming months once I get my OS to boot off of CD. It is 32-bit at the moment, but I want to go to long mode and from what I've read I am stuck using paging, when my OS is flat memory based, can I set one "large" page? I assume there isn't enough bits in the table (sorry, my vernacular is likely wrong, I'm relearning this since being away for 6 ish years), that I can't directly address say 40 bits of memory, perhaps? Or can I? References are always welcome (even if they cost money, I'll go buy them).

14 Dec 2011, 23:39

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20761
Location: In your JS exploiting you and your system

revolution 15 Dec 2011, 00:01

smiddy wrote:

I assume there isn't enough bits in the table (sorry, my vernacular is likely wrong, I'm relearning this since being away for 6 ish years), that I can't directly address say 40 bits of memory, perhaps? Or can I? References are always welcome (even if they cost money, I'll go buy them).

No need to assume anything. Paging is fully described in the Intel/AMD manuals. And they are free.

15 Dec 2011, 00:01

smiddy

Joined: 31 Oct 2004
Posts: 557

smiddy 15 Dec 2011, 01:44

Thanks, when I get to that point. I am debugging my boot loader from CD. Within the next month or so...

15 Dec 2011, 01:44

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