* dear list
@ 2010-09-02 6:51 gaoqiang
2010-10-14 5:18 ` Américo Wang
0 siblings, 1 reply; 2+ messages in thread
From: gaoqiang @ 2010-09-02 6:51 UTC (permalink / raw)
To: linux-kernel
I'm a newbie and got some question when learning the linux kernel
about a macro:
page_to_pfn(pg)
I traced its definition,and finally got that:
#define __page_to_pfn(page) ((unsigned long)((page) - mem_map) +
ARCH_PFN_OFFSET)
why hot ((unsigned long)((page)-mem_map + ARCH_PFN_OFFSET)/sizeof
(struct page)
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: dear list
2010-09-02 6:51 dear list gaoqiang
@ 2010-10-14 5:18 ` Américo Wang
0 siblings, 0 replies; 2+ messages in thread
From: Américo Wang @ 2010-10-14 5:18 UTC (permalink / raw)
To: gaoqiang; +Cc: linux-kernel
On Thu, Sep 02, 2010 at 02:51:48PM +0800, gaoqiang wrote:
>I'm a newbie and got some question when learning the linux kernel
>
>about a macro:
>
>page_to_pfn(pg)
>
>I traced its definition,and finally got that:
>
>#define __page_to_pfn(page) ((unsigned long)((page) - mem_map) +
>ARCH_PFN_OFFSET)
>
>
>why hot ((unsigned long)((page)-mem_map + ARCH_PFN_OFFSET)/sizeof
>(struct page)
>
Sorry for the really long delay.
That is because both 'page' and 'mem_map' have type 'struct page *'.
^ permalink raw reply [flat|nested] 2+ messages in thread
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