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Date: Thu, 07 Jun 2007 21:29:28 +1000
From: Nick Piggin <nickpiggin@yahoo.com.au>
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To: "Robert P. J. Day" <rpjday@mindspring.com>
CC: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: why does the macro "ZERO_PAGE" take an argument?
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Robert P. J. Day wrote:
>   probably making a fool of myself here, but what is the purpose of
> that single argument to the macro "ZERO_PAGE"?
> 
> $ grep -r "define ZERO_PAGE" include
> include/asm-frv/pgtable.h:#define ZERO_PAGE(vaddr)      ({ BUG(); NULL; })
> include/asm-frv/pgtable.h:#define ZERO_PAGE(vaddr)      virt_to_page(empty_zero_page)
> include/asm-v850/pgtable.h:#define ZERO_PAGE(vaddr)     ((void *)0x87654321)
> include/asm-mips/pgtable.h:#define ZERO_PAGE(vaddr) \
> include/asm-blackfin/pgtable.h:#define ZERO_PAGE(vaddr) (virt_to_page(0))
> include/asm-parisc/pgtable.h:#define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))
> include/asm-alpha/pgtable.h:#define ZERO_PAGE(vaddr)    (virt_to_page(ZERO_PGE))
> ...
> 
>   AFAICT, there are no definitions of that macro that actually use
> that argument.  is that some kind of historical cruft?

MIPS?

-- 
SUSE Labs, Novell Inc.