>Hi,
>
>What does the PAGE_MASK macro do in the kernel ?
>
>The PAGE_MASK macro is defined as
>
>/* PAGE_SHIFT determines the page size */
>#define PAGE_SHIFT 12
>#define PAGE_SIZE (1UL << PAGE_SHIFT)
>#define PAGE_MASK (~(PAGE_SIZE-1))
>
>in /linux/include/asm-i386/page.h
>
>and the macro usage is like
>
>pos=filp->f_pos;
>ppos=pos&PAGE_MASK
ppos will result something like the offset from the start of a page. It
will mean how much pos is disaligned by the 4k boundaries.
Andrea[s] Arcangeli
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