On Monday 27 March 2006 20:43, JimD <[EMAIL PROTECTED]> wrote about 'Re: [gentoo-user] chroot': > On Mon, 27 Mar 2006 19:56:22 -0600 > "Boyd Stephen Smith Jr." <[EMAIL PROTECTED]> wrote: > > Yes, that's an option to, although with more than ~768K of ram it's > > not ideal. > > Why is that? I thought 32-bit should have no problems addressing > 2GB?
I'm not sure about the exact technical reasons, but basically, if you want more than 1G total visible you have to introduce the kernel BIGMEM or HUGEMEM modes; both of which add a software component to each memory access, from what I understand. Without them (and no other kernel hacking) your get a 768m/256m user/kernel split; With BIGMEM this moves up to a 3m/1m user/kernel split; With HUGEMEM I'm not sure if there's a split at all, but it slower than using the hw available in your x86_64 chipset. Using the native, flat 40- or 48-bit addressing of 64-bit mode is much more efficient than any of the kernel hackery that takes place above 768M. Plus, with a 64-bit kernel, it'll have access to the 64-bit specific registers. :) -- "If there's one thing we've established over the years, it's that the vast majority of our users don't have the slightest clue what's best for them in terms of package stability." -- Gentoo Developer Ciaran McCreesh
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