Message-ID: <4A4E609C.5030608@zytor.com>
Date: Fri, 03 Jul 2009 12:48:44 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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CC: Jeremy Fitzhardinge <jeremy@goop.org>, linux-kernel@vger.kernel.org,
       Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
       the arch/x86 maintainers <x86@kernel.org>,
       Andi Kleen <ak@linux.intel.com>
Subject: Re: [Bug Fix]: Do 32-bit table calculations in pre-processor
References: <200907031314.36243.lkml@morethan.org> <200907031403.34566.lkml@morethan.org> <4A4E58AC.7010905@zytor.com> <200907031441.04604.lkml@morethan.org>
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Michael S. Zick wrote:
> 
> Good point: (1<<(32-PAGE_SIFT)) would handle other than 4k pages.
> 
> I just hardcoded it as a working example of the change from setting
> the page table size by design rather than numeric error.
> 

As Jeremy pointed out, it's not wrong as written.  gas by design uses
arbitrary-precision arithmetic, and even if it didn't, it would still be
correct: (1 << 32) would collapse to 0, so all the rest of the
calculations would still be right.

Any way you can dump out this value from the vmlinux file (nm vmlinux |
grep MAPPING_BEYOND_END) in both cases?  What version of as/binutils do
you have installed?

> And yes, it has 512Mbyte of ram, so 1/2Mbyte page table sounds right to me.

/proc/cpuinfo, please?

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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