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Reply-To: <imran.badr@cavium.com>
From: "Imran Badr" <imran.badr@cavium.com>
To: "'lkml'" <linux-kernel@vger.kernel.org>
Subject: DMA from high memory regions
Date: Tue, 25 Jun 2002 16:29:58 -0700
Message-ID: <002501c21ca0$3940ac40$9e10a8c0@IMRANPC>
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Hi,

I am trying to setup DMA to/from user space. I get a user pointer in my
device driver, from which I build up kiobuf and call map_user_kiobuf. After
this, I call kmap to map pages to kernel virtual space and then virt_to_bus
to get bus address. Now if I define CONFIG_HIGHMEM and that page happens to
be in the memory region near 1GB then DMA never happens and I donot see any
data in result pointer. If CONFIG_HIGHMEM is not defined, then everything
works perfectly. Please suggest any solution.

Thanks,
Imran.



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