PAE with dragonfly
sdrhodus at gmail.com
Wed Jun 8 12:03:44 PDT 2005
On 6/8/05, Craig Dooley <xlnxminusx at xxxxxxxxx> wrote:
> Doesn't AMD64 use PAE for large address spaces? I thought the Page
> Table structures were the same for both.
No, on AMD64 when operating in long mode the address space is 64bit.
PAE is a 32bit hack that lets you access a few more bits. 34, 37 ? I
don't recall exactly off the top of my head.
There are some interesting uses for PAE on the regular ia32
architecture such as allowing the kernel a full 4Gig memory and the
userland a full 4Gig of memory. This actually makes the kernels life
a lot easier, though almost no one has this type of setup so its
mostly a moot development point. About a year ago I had a working
implementation of PAE working on DragonFly, though I only had one test
machine with 4.5 Gigs of memory. I also only had access to the
machine for a few days so I never had time to go through and optimize
I can look around for the old patch if someone has access to some
machines with more than 4 gigs of memory and someone that also has
time to revive it.
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