Messages in this thread | | | Date | Fri, 03 Jul 2009 12:08:40 -0700 | From | Jeremy Fitzhardinge <> | Subject | Re: [Bug Fix]: Do 32-bit table calculations in pre-processor |
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On 07/03/09 11:38, Michael S. Zick wrote: > I make no claims for it at the moment - too early in the test process. > Just the general observation that it takes 0.5M to describe 0.5G of ram. > Only if you're using 4k pages. With large pages, 1 pte can map 2M, so 256 entries can map 512M, so you only need 1/2 a page of pagetable (assuming PAE; if not a single entry can map 4M).
> Also, > the observation that (1<<32) drops the bit off the left end of a 32-bit value. > You can see the result in the portion of the post you snipped out. ;) >
Those computations aren't done as 32-bit.
$ as << EOF .data .byte (1 << 100) >> 100 EOF $ objdump -D a.out
a.out: file format elf64-x86-64
Disassembly of section .data:
0000000000000000 <.data>: 0: 01 .byte 0x1
J
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