Re: [RFC PATCH] fix problems with NETIF_F_HIGHDMA in networking drivers
From: FUJITA Tomonori <hidden>
Date: 2010-02-27 18:38:29
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On Sat, 27 Feb 2010 11:59:47 -0600 Robert Hancock [off-list ref] wrote:
On Sat, Feb 27, 2010 at 3:53 AM, David Miller [off-list ref] wrote:quoted
From: Robert Hancock <redacted> Date: Fri, 26 Feb 2010 21:08:04 -0600quoted
That seems like a reasonable approach to me. Only question is how to implement the check for DMA_64BIT. Can we just check page_to_phys on each of the pages in the skb to see if it's > 0xffffffff ? Are there any architectures where it's more complicated than that?On almost every platform it's "more complicated than that". This is the whole issue. What matters is the final DMA address and since we have IOMMUs and the like, it is absolutely not tenable to solve this by checking physical address attributes.Yeah, physical address isn't quite right. There is a precedent for
Probably, you need to check PCI_DMA_BUS_IS_PHYS. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html