On Thu, 19 May 2005 22:15:55 -0400 Walter Dnes <[EMAIL PROTECTED]> wrote: | Does Gentoo do anything with the extra 64 bits?
64 bit code is actually slower than 32 bit code for anything except certain dedicated applications. What you do gain is increased address space, which only makes a difference if you're going over (for x86/amd64) about 900MBytes of RAM. However... amd64 is not just x86 extended to 64 bit. By using 64 bit mode you're gaining a whole load of other extras, such as a heap of extra general purpose registers, which makes up for the 64 bit code penalty. In an ideal world, your amd64 box would run a pure 64 bit kernel and a 64 bit int / 32 bit pointer userland, and still have access to the extra registers. Unfortunately, amd64 can't do this (unlike, say, MIPS). Note that people who have only read the marketing material and who don't realise what various non-x86 archs get up to will tell you that what I just said was wrong and that "64 bit is just plain faster". It's not, and things are not as simple as the marketroids would like you to believe, but because of limitations in amd64 you're still better going for 64 bit userland and kernel. -- Ciaran McCreesh : Gentoo Developer (Vim, Shell tools, Fluxbox, Cron) Mail : ciaranm at gentoo.org Web : http://dev.gentoo.org/~ciaranm
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