From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 01/10] ARM: change ARM_DMA_ZONE_SIZE into a variable
Date: Fri, 8 Jul 2011 09:59:54 +0100 [thread overview]
Message-ID: <20110708085954.GA2414@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <81e4ac16-db7b-47a0-9f93-632a5d9f898d@VA3EHSMHS028.ehs.local>
On Thu, Jul 07, 2011 at 11:08:38AM -0600, John Linn wrote:
> If I'm following this right....
>
> We have a hole at the start of physical memory (when it's at 0) so that
> DMA can't DMA into it. Sounds like that won't work for us?
That depends what you mean by that.
If you're saying that your physical RAM starts at some non-zero address,
then that isn't a problem. We have lots of ARM platforms where that is
true.
If you're saying that the first N MB of RAM can't be DMA'd to, then that
is a problem as the kernel has no way to be told about that restriction.
The best we can manage is to avoid freeing that memory into the normal
allocation pools.
We do have a very small number of platforms where that's true, but we
'work around' that by having the kernel occupy that space. If N MB is
less than sizeof(kernel) + 32K then you haven't lost much.
next prev parent reply other threads:[~2011-07-08 8:59 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-06 2:30 [PATCH 01/10] ARM: change ARM_DMA_ZONE_SIZE into a variable Nicolas Pitre
2011-07-06 2:30 ` [PATCH 02/10] ARM: add dma_zone_size to the machine_desc structure Nicolas Pitre
2011-07-06 23:10 ` Russell King - ARM Linux
2011-07-07 2:59 ` Nicolas Pitre
2011-07-06 2:30 ` [PATCH 03/10] ARM: mach-davinci: move from ARM_DMA_ZONE_SIZE to mdesc->dma_zone_size Nicolas Pitre
2011-07-06 2:30 ` [PATCH 04/10] ARM: mach-h720x: " Nicolas Pitre
2011-07-06 2:30 ` [PATCH 05/10] ARM: mach-ixp4xx: " Nicolas Pitre
2011-07-06 23:12 ` Russell King - ARM Linux
2011-07-07 3:31 ` Nicolas Pitre
2011-07-06 2:30 ` [PATCH 06/10] ARM: mach-pxa: " Nicolas Pitre
2011-07-06 2:30 ` [PATCH 07/10] ARM: mach-realview: " Nicolas Pitre
2011-07-06 23:15 ` Russell King - ARM Linux
2011-07-07 3:59 ` Nicolas Pitre
2011-07-06 2:30 ` [PATCH 08/10] ARM: mach-sa1100: move " Nicolas Pitre
2011-07-06 2:30 ` [PATCH 09/10] ARM: mach-shark: " Nicolas Pitre
2011-07-06 2:30 ` [PATCH 10/10] ARM: ARM_DMA_ZONE_SIZE is no more Nicolas Pitre
2011-07-06 2:48 ` [PATCH 01/10] ARM: change ARM_DMA_ZONE_SIZE into a variable Barry Song
2011-07-06 3:12 ` Nicolas Pitre
2011-07-06 23:09 ` Russell King - ARM Linux
2011-07-07 2:50 ` Nicolas Pitre
2011-07-07 16:17 ` Arnd Bergmann
2011-07-07 17:08 ` John Linn
2011-07-07 17:40 ` Arnd Bergmann
2011-07-08 8:59 ` Russell King - ARM Linux [this message]
2011-07-08 13:58 ` John Linn
2011-07-08 16:23 ` Russell King - ARM Linux
2011-07-07 18:15 ` Grant Likely
2011-07-06 23:04 ` Russell King - ARM Linux
2011-07-07 2:46 ` Nicolas Pitre
2011-07-08 12:14 ` Russell King - ARM Linux
2011-07-08 20:30 ` Russell King - ARM Linux
2011-07-09 8:12 ` Russell King - ARM Linux
2011-07-09 8:13 ` Russell King - ARM Linux
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