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From: "David S. Miller" <davem@redhat.com>
To: groudier@free.fr
Cc: axboe@suse.de, gibbs@scsiguy.com, LB33JM16@yahoo.com,
	linux-kernel@vger.kernel.org
Subject: Re: highmem, aic7xxx, and vfat: too few segs for dma mapping
Date: Mon, 10 Dec 2001 22:12:31 -0800 (PST)	[thread overview]
Message-ID: <20011210.221231.72737317.davem@redhat.com> (raw)
In-Reply-To: <20011210194953.L2225-100000@gerard>
In-Reply-To: <20011210200302.GA13498@suse.de> <20011210194953.L2225-100000@gerard>

   From: Gérard Roudier <groudier@free.fr>
   Date: Mon, 10 Dec 2001 20:21:21 +0100 (CET)
   
   Btw, a 16 MB boundary limitation would have no significant impact on
   performance and would have the goodness of avoiding some hardware bugs not
   only on a few Symbios devices in my opinion. As we know, numerous modern
   cores still have rests of the ISA epoch in their guts. So, in my opinion,
   the 16 MB boundary limitation should be the default on systems where
   reliability is the primary goal.

Complications arrive when IOMMU starts to remap things into a virtual
32-bit bus space as happens on several platforms now.

Jen's block layer knows nothing about what we will do here, since
he only really has access to physical addresses.

Only after the pci_map_sg() call can you inspect DMA addresses and
apply such workarounds.

  reply	other threads:[~2001-12-10 22:22 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-12-10  1:32 highmem, aic7xxx, and vfat: too few segs for dma mapping LBJM
2001-12-10 18:40 ` Justin T. Gibbs
2001-12-10 19:21   ` Jens Axboe
2001-12-10 19:50     ` Justin T. Gibbs
2001-12-10 20:03       ` Jens Axboe
2001-12-10 19:21         ` Gérard Roudier
2001-12-11  6:12           ` David S. Miller [this message]
2001-12-11 17:01             ` Gérard Roudier
2001-12-12  9:36               ` Jens Axboe
2001-12-12 13:32                 ` Andrea Arcangeli
2001-12-12 17:22                   ` Gérard Roudier
2001-12-12 22:19                     ` Andrea Arcangeli
2001-12-12 20:24                       ` Gérard Roudier
2001-12-13  0:26                         ` David S. Miller
2001-12-13 16:17                           ` Gérard Roudier
2001-12-13 20:30                             ` David S. Miller
2001-12-13 18:13                               ` Gérard Roudier
2001-12-13  0:06                     ` David S. Miller
2001-12-13 16:39                       ` Gérard Roudier
2001-12-12 16:39                 ` Gérard Roudier
2001-12-13 20:10       ` Steve Lord
2001-12-13 20:15         ` Justin T. Gibbs
2001-12-13 20:29           ` Steve Lord
2001-12-13 20:48             ` Justin T. Gibbs
2001-12-13 20:58               ` Steve Lord
2001-12-13 21:17                 ` Steve Lord
2001-12-13 21:27                   ` David S. Miller
2001-12-14 15:16                     ` Jens Axboe
2001-12-14 16:15                       ` Jens Axboe
2001-12-14 16:22                         ` Alok K. Dhir
2001-12-14 16:32                           ` Jens Axboe
2001-12-14 16:25                         ` Stephen Lord
2001-12-14 16:24                           ` Jens Axboe

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