From: "Michael Chan" <mchan@broadcom.com>
To: "David Miller" <davem@davemloft.net>
Cc: jeff@garzik.org, "netdev" <netdev@vger.kernel.org>
Subject: Re: [PATCH 3/20][BNX2]: Add 40-bit DMA workaround for 5708.
Date: Wed, 02 May 2007 14:27:49 -0700 [thread overview]
Message-ID: <1178141269.4820.109.camel@dell> (raw)
In-Reply-To: <20070502.124000.116378720.davem@davemloft.net>
On Wed, 2007-05-02 at 12:40 -0700, David Miller wrote:
> From: "Michael Chan" <mchan@broadcom.com>
> Date: Wed, 2 May 2007 08:23:40 -0700
>
> > A non-IOMMU system using 64-bit dma_addr_t will always set
> > CONFIG_HIGHMEM, right?
>
> Nope, IA-64 is at least one example.
>
> IA-64 has both IOMMU and non-IOMMU configurations, and
> never sets HIGHMEM.
>
I see. So IA64 always uses the SWIOTLB when it doesn't have IOMMU then?
I'm a bit confused. Is it enough to just set the DMA mask to 40-bit and
forget about all this checking? I thought that wasn't enough. A tx
packet can be anywhere in 64-bit memory. When it gets to the driver,
pci_map will not do any translation even if DMA mask is set to 40-bit if
it doesn't have IOMMU. Is that right?
next prev parent reply other threads:[~2007-05-02 20:41 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-02 1:13 [PATCH 3/20][BNX2]: Add 40-bit DMA workaround for 5708 Michael Chan
2007-05-02 7:06 ` Jeff Garzik
2007-05-02 7:12 ` David Miller
2007-05-02 15:23 ` Michael Chan
2007-05-02 15:28 ` Christoph Hellwig
2007-05-02 15:29 ` Jeff Garzik
2007-05-02 18:23 ` Michael Chan
2007-05-02 18:24 ` Jeff Garzik
2007-05-02 20:02 ` Michael Chan
2007-05-02 20:30 ` Jeff Garzik
2007-05-02 22:48 ` Christoph Hellwig
2007-05-02 22:50 ` David Miller
2007-05-02 19:40 ` David Miller
2007-05-02 21:27 ` Michael Chan [this message]
2007-05-02 21:45 ` David Miller
2007-05-02 23:28 ` Michael Chan
2007-05-02 22:48 ` David Miller
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