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Date: Fri, 3 Jul 2009 14:13:15 -0500 From: "Michael S. Zick" <lkml@...ethan.org> To: Jeremy Fitzhardinge <jeremy@...p.org> Cc: Andi Kleen <andi@...stfloor.org>, linux-kernel@...r.kernel.org Subject: Re: [Bug Fix]: Do 32-bit table calculations in pre-processor On Fri July 3 2009, Jeremy Fitzhardinge wrote: > 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). > Ah, but you can't assume that - look at your VIA-C7M tech sheet - NO PAE. Mike > > 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. > Try ending the filename in ".S" and passing it to gcc, like the build system does. And while your at it, thank A.K. for snipping off the before/after dmesg. Mike > > $ 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 > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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