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Date: Fri, 9 Jul 2004 16:40:56 -0700
From: Andrew Morton <akpm@osdl.org>
To: James Bottomley <James.Bottomley@SteelEye.com>
Cc: wli@holomorphy.com, linux-kernel@vger.kernel.org
Subject: Re: 2.6.7-mm7
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James Bottomley <James.Bottomley@SteelEye.com> wrote:
>
> On Fri, 2004-07-09 at 17:14, Andrew Morton wrote:
> > btw, James, I'm unable to convince myself that
> > dma_mark_declared_memory_occupied() reserves enough pages if device_addr is
> > not page-aligned.  Could you double-check that?  If all callers are
> > expected to use a page-aligned address then a BUG_ON might be appropriate. 
> > Or a comment.
> 
> Oh, you mean when addr isn't page aligned and size causes it just to
> span a page, like addr = 0xfff, size=2?

yup.

> You're right, it doesn't.  How about the attached

seems to work OK.


#define PAGE_SIZE 4096
#define PAGE_MASK ~4095
#define PAGE_SHIFT 12

main()
{
	int addr, size;

	for (addr = 1; addr < 8192; addr += 1024) {
		for (size = -1; size < 8192; size += 1024) {
			int pages;

			pages = (size + (addr & ~PAGE_MASK) + PAGE_SIZE - 1) >> PAGE_SHIFT;
			printf("addr:%06x size:%06x pages:%d\n",
				addr, size, pages);
		}
	}
}