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From: Julian S. <js...@ac...> - 2005-06-22 13:12:07
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> The main advantage of PIE is that it gives us more space for the > client on systems where the kernel gives us more of the address space > to play with. On ppc32 systems, in many configurations we only get > 2GB address space, but on some machines we get 3GB, and on a ppc64 > machine we get a full 4GB of address space for 32-bit processes. If > we have a fixed base for stage2 we have to pick 0x70000000 and thus > waste 2GB of address space on a ppc64 machine (such as my G5). Just checking my understanding is correct: the fact that a fixed base of (say) 0x70000000 for stage2 causes a wastage of address space is a consequence only of the current address-space-layout scheme V uses, correct? So if I just compile some program with and without PIE and run it natively, the amount of address space available to it is unaffected by the PIEness, correct? Motivation for these questions is that there's been for a while a plan to rewrite the address space manage (m_aspacemgr) to be more flexible in layout. I want to be sure that if that happens, it will render moot the issue of limited address space when PIE is not used. J |