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From: Roland Dreier <roland@topspin.com>
To: "David S. Miller" <davem@redhat.com>
Cc: wjhun@ayrnetworks.com, paulus@samba.org, linux-kernel@vger.kernel.org
Subject: Re: PCI DMA to small buffers on cache-incoherent arch
Date: 10 Jun 2002 21:39:27 -0700	[thread overview]
Message-ID: <52d6uy77k0.fsf@topspin.com> (raw)
In-Reply-To: <20020610110740.B30336@ayrnetworks.com> <20020610.201033.66168406.davem@redhat.com> <52lm9m7969.fsf@topspin.com> <20020610.212135.129520403.davem@redhat.com>


   	struct something {
   	        int field1;
   	        char dma_buffer[SMALLER_THAN_CACHE_LINE];
   	        int field2;
   	};
   
   	struct something *dev = kmalloc(sizeof *dev, GFP_KERNEL);
   
    David> How about allocating struct something using pci_pool?

The problem is the driver can't safely touch field1 or field2 near the
DMA (it might pull the cache line back in too soon, or dirty the cache
line and have it written back on top of DMA'ed data)

Best,
  Roland


  reply	other threads:[~2002-06-11  4:39 UTC|newest]

Thread overview: 99+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-06-08 20:38 PCI DMA to small buffers on cache-incoherent arch Roland Dreier
2002-06-08 13:58 ` Anton Blanchard
2002-06-09  0:52   ` Roland Dreier
2002-06-08 23:03 ` David S. Miller
2002-06-09  0:40   ` Roland Dreier
2002-06-09  0:53     ` David S. Miller
2002-06-09  1:26       ` Roland Dreier
2002-06-09  5:29         ` David S. Miller
2002-06-09  6:16           ` Roland Dreier
2002-06-10 16:03             ` Roland Dreier
2002-06-11 14:04               ` David Woodhouse
2002-06-09  6:45           ` Oliver Neukum
2002-06-10  4:24             ` David S. Miller
2002-06-10 10:00               ` Oliver Neukum
2002-06-10 10:24                 ` David S. Miller
2002-06-09  9:51           ` Paul Mackerras
2002-06-09 10:54             ` Benjamin Herrenschmidt
2002-06-10  4:27             ` David S. Miller
2002-06-10 15:59               ` Roland Dreier
2002-06-10 17:03                 ` Tom Rini
2002-06-10 17:22                   ` Oliver Neukum
2002-06-10 17:29                     ` Tom Rini
2002-06-10 17:39                       ` Oliver Neukum
2002-06-10 19:03                       ` Roland Dreier
2002-06-10 19:14                         ` Tom Rini
2002-06-10 19:21                           ` Roland Dreier
2002-06-10 19:26                             ` Tom Rini
2002-06-10 17:57                     ` Russell King
2002-06-10 17:28                   ` Roland Dreier
2002-06-10 18:07               ` William Jhun
2002-06-10 18:29                 ` William Jhun
2002-06-10 18:33                 ` Mark Zealey
2002-06-10 18:44                   ` Oliver Neukum
2002-06-11  3:10                 ` David S. Miller
2002-06-11  4:04                   ` Roland Dreier
2002-06-11  4:16                     ` Brad Hards
2002-06-11  4:24                       ` Roland Dreier
2002-06-11  4:24                         ` David S. Miller
2002-06-11  4:21                     ` David S. Miller
2002-06-11  4:39                       ` Roland Dreier [this message]
2002-06-11  4:38                         ` David S. Miller
2002-06-11  6:23                           ` Oliver Neukum
2002-06-11  6:38                             ` David S. Miller
2002-06-11  7:38                               ` Oliver Neukum
2002-06-11  7:36                                 ` David S. Miller
2002-06-11  7:43                                   ` David S. Miller
2002-06-11  8:07                                     ` Oliver Neukum
2002-06-11  8:15                                       ` David S. Miller
2002-06-11 12:06                                         ` Oliver Neukum
2002-06-11 12:04                                           ` David S. Miller
2002-06-11 14:23                                             ` Oliver Neukum
2002-06-14  4:14                                               ` David S. Miller
2002-06-11 18:26                                             ` Roland Dreier
2002-06-11 17:29                                               ` Benjamin Herrenschmidt
2002-06-12 12:02                                                 ` Oliver Neukum
2002-06-11 20:06                                                   ` Benjamin Herrenschmidt
2002-06-12 12:02                                                   ` David S. Miller
2002-06-11 23:00                                               ` Thunder from the hill
2002-06-11 23:56                                                 ` Roland Dreier
2002-06-12  0:09                                                   ` Thunder from the hill
2002-06-11 15:57                                     ` William Jhun
2002-06-12  9:06                                     ` Pavel Machek
2002-06-12 20:16                                       ` David S. Miller
2002-06-12 11:47                 ` David S. Miller
2002-06-12 12:08                   ` Oliver Neukum
2002-06-14  4:41                     ` David S. Miller
2002-06-12 16:09                   ` William Jhun
2002-06-09  1:30   ` Albert D. Cahalan
2002-06-09  5:29     ` David S. Miller
2002-06-09  6:33       ` Albert D. Cahalan
2002-06-09  6:50         ` Oliver Neukum
2002-06-09  6:57           ` Albert D. Cahalan
2002-06-09  7:15             ` Oliver Neukum
2002-06-09  8:48         ` Russell King
2002-06-09 15:42           ` Albert D. Cahalan
2002-06-09 23:26           ` Oliver Neukum
  -- strict thread matches above, loose matches on Subject: below --
2002-06-11  5:31 David Brownell
2002-06-11  5:44 ` David S. Miller
2002-06-11 15:12   ` David Brownell
2002-06-11 15:44     ` Oliver Neukum
2002-06-12  3:25     ` David S. Miller
2002-06-11 17:33       ` Benjamin Herrenschmidt
2002-06-12  9:42         ` David S. Miller
2002-06-12 14:14           ` David Brownell
2002-06-12 15:00             ` Benjamin Herrenschmidt
2002-06-12 18:44             ` Roland Dreier
2002-06-12 19:13               ` David Brownell
2002-06-12 19:58                 ` Oliver Neukum
2002-06-12 22:51                   ` David S. Miller
2002-06-12 23:17                     ` Oliver Neukum
2002-06-13  4:57                   ` David Brownell
2002-06-12 22:46                 ` David S. Miller
2002-06-13  5:13                   ` David Brownell
2002-06-13  9:38                     ` David S. Miller
2002-06-12 22:50                 ` David S. Miller
2002-06-12  6:25       ` David Brownell
2002-06-12  6:24         ` David S. Miller
2002-06-12  7:06           ` David Brownell
2002-06-12  9:22             ` David S. Miller

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