On Wed, Jul 21, 2010 at 09:25:28PM -0700, Zach Pfeffer wrote:
Yes it is a problem, as Russell has brought up, but there's something
I probably haven't communicated well. I'll use the following example:
There are 3 devices: A CPU, a decoder and a video output device. All 3
devices need to map
On Wed, Jul 21, 2010 at 09:30:34PM -0700, Zach Pfeffer wrote:
This goes to the nub of the issue. We need a lot of 1 MB physically
contiguous chunks. The system is going to fragment and we'll never get
our 12 1 MB chunks that we'll need, since the DMA API allocator uses
the system pool it will
On Thu, Jul 22, 2010 at 08:34:55AM +0100, Russell King - ARM Linux wrote:
On Wed, Jul 21, 2010 at 09:25:28PM -0700, Zach Pfeffer wrote:
Yes it is a problem, as Russell has brought up, but there's something
I probably haven't communicated well. I'll use the following example:
There are 3
On Thu, Jul 22, 2010 at 08:39:17AM +0100, Russell King - ARM Linux wrote:
On Wed, Jul 21, 2010 at 09:30:34PM -0700, Zach Pfeffer wrote:
This goes to the nub of the issue. We need a lot of 1 MB physically
contiguous chunks. The system is going to fragment and we'll never get
our 12 1 MB
On Thu, Jul 22, 2010 at 01:43:26PM +0900, FUJITA Tomonori wrote:
On Wed, 21 Jul 2010 21:30:34 -0700
Zach Pfeffer zpfef...@codeaurora.org wrote:
On Wed, Jul 21, 2010 at 10:44:37AM +0900, FUJITA Tomonori wrote:
On Tue, 20 Jul 2010 15:20:01 -0700
Zach Pfeffer zpfef...@codeaurora.org
*
This is difficult to achieve without remapping kernel memory using L2
page tables, so we can unmap pages on 4K page granularity. That's
going to increase TLB overhead and result in lower system performance
as
On Tue, Jul 20, 2010 at 09:44:12PM -0400, Timothy Meade wrote:
On Tue, Jul 20, 2010 at 8:44 PM, Zach Pfeffer zpfef...@codeaurora.org wrote:
On Mon, Jul 19, 2010 at 05:21:35AM -0400, Tim HRM wrote:
On Fri, Jul 16, 2010 at 8:01 PM, Larry Bassel lbas...@codeaurora.org
wrote:
On 16 Jul 10
On Mon, Jul 19, 2010 at 12:44:49AM -0700, Eric W. Biederman wrote:
Zach Pfeffer zpfef...@codeaurora.org writes:
On Thu, Jul 15, 2010 at 09:55:35AM +0100, Russell King - ARM Linux wrote:
On Wed, Jul 14, 2010 at 06:29:58PM -0700, Zach Pfeffer wrote:
The VCM ensures that all mappings that
On Wed, Jul 21, 2010 at 10:44:37AM +0900, FUJITA Tomonori wrote:
On Tue, 20 Jul 2010 15:20:01 -0700
Zach Pfeffer zpfef...@codeaurora.org wrote:
I'm not saying that it's reasonable to pass (or even allocate) a 1MB
buffer via the DMA API.
But given a bunch of large chunks of memory,
On Wed, 21 Jul 2010 21:30:34 -0700
Zach Pfeffer zpfef...@codeaurora.org wrote:
On Wed, Jul 21, 2010 at 10:44:37AM +0900, FUJITA Tomonori wrote:
On Tue, 20 Jul 2010 15:20:01 -0700
Zach Pfeffer zpfef...@codeaurora.org wrote:
I'm not saying that it's reasonable to pass (or even allocate)
On Tue, Jul 20, 2010 at 09:54:33PM +0100, Russell King - ARM Linux wrote:
On Tue, Jul 20, 2010 at 01:45:17PM -0700, Zach Pfeffer wrote:
You can also conflict in access permissions which can and do conflict
(which are what multiple mappings are all about...some buffer can get
some access,
Russell-
If a driver wants to allow a device to access memory (and cache coherency
is off/not present for device addesses), the driver needs to remap that
memory as non-cacheable. Suppose there exists a chunk of
physically-contiguous memory (say, memory reserved for device use) that
happened to
On Mon, Jul 19, 2010 at 05:21:35AM -0400, Tim HRM wrote:
On Fri, Jul 16, 2010 at 8:01 PM, Larry Bassel lbas...@codeaurora.org wrote:
On 16 Jul 10 08:58, Russell King - ARM Linux wrote:
On Thu, Jul 15, 2010 at 08:48:36PM -0400, Tim HRM wrote:
Interesting, since I seem to remember the MSM
On Tue, Jul 20, 2010 at 8:44 PM, Zach Pfeffer zpfef...@codeaurora.org wrote:
On Mon, Jul 19, 2010 at 05:21:35AM -0400, Tim HRM wrote:
On Fri, Jul 16, 2010 at 8:01 PM, Larry Bassel lbas...@codeaurora.org wrote:
On 16 Jul 10 08:58, Russell King - ARM Linux wrote:
On Thu, Jul 15, 2010 at
What is the problem about mapping a 1MB buffer with the DMA API?
Possibly, an IOMMU can't find space for 1MB but it's not the problem of
the DMA API.
As you have pointed out, one of the issues is that allocation can fail.
While technically VCMM allocations can fail as well, these allocations
-Original Message-
From: linux-arm-kernel-boun...@lists.infradead.org [mailto:linux-arm-
kernel-boun...@lists.infradead.org] On Behalf Of Russell King - ARM Linux
Sent: Wednesday, July 21, 2010 4:00 AM
To: step...@codeaurora.org
Cc: linux-a...@vger.kernel.org; dwal...@codeaurora.org;
On Thu, Jul 15, 2010 at 09:55:35AM +0100, Russell King - ARM Linux wrote:
On Wed, Jul 14, 2010 at 06:29:58PM -0700, Zach Pfeffer wrote:
The VCM ensures that all mappings that map a given physical buffer:
IOMMU mappings, CPU mappings and one-to-one device mappings all map
that buffer using
Zach Pfeffer zpfef...@codeaurora.org writes:
On Thu, Jul 15, 2010 at 09:55:35AM +0100, Russell King - ARM Linux wrote:
On Wed, Jul 14, 2010 at 06:29:58PM -0700, Zach Pfeffer wrote:
The VCM ensures that all mappings that map a given physical buffer:
IOMMU mappings, CPU mappings and
On Wed, Jul 14, 2010 at 06:41:48PM -0700, Zach Pfeffer wrote:
On Thu, Jul 15, 2010 at 08:07:28AM +0900, FUJITA Tomonori wrote:
Why we we need a new abstraction layer to solve the problem that the
current API can handle?
The current API can't really handle it because the DMA API doesn't
On Fri, Jul 16, 2010 at 8:01 PM, Larry Bassel lbas...@codeaurora.org wrote:
On 16 Jul 10 08:58, Russell King - ARM Linux wrote:
On Thu, Jul 15, 2010 at 08:48:36PM -0400, Tim HRM wrote:
Interesting, since I seem to remember the MSM devices mostly conduct
IO through regions of normal RAM,
On 7/16/2010 12:58 AM, Russell King - ARM Linux wrote:
As the patch has been out for RFC since early April on the linux-arm-kernel
mailing list (Subject: [RFC] Prohibit ioremap() on kernel managed RAM),
and no comments have come back from Qualcomm folk.
Would it be unreasonable to allow a
On Thu, Jul 15, 2010 at 08:48:36PM -0400, Tim HRM wrote:
Interesting, since I seem to remember the MSM devices mostly conduct
IO through regions of normal RAM, largely accomplished through
ioremap() calls.
Without more public domain documentation of the MSM chips and AMSS
interfaces I
On 16 Jul 10 08:58, Russell King - ARM Linux wrote:
On Thu, Jul 15, 2010 at 08:48:36PM -0400, Tim HRM wrote:
Interesting, since I seem to remember the MSM devices mostly conduct
IO through regions of normal RAM, largely accomplished through
ioremap() calls.
Without more public domain
On Wed, Jul 14, 2010 at 06:29:58PM -0700, Zach Pfeffer wrote:
The VCM ensures that all mappings that map a given physical buffer:
IOMMU mappings, CPU mappings and one-to-one device mappings all map
that buffer using the same (or compatible) attributes. At this point
the only attribute that
On Wed, Jul 14, 2010 at 10:59:38AM +0900, FUJITA Tomonori wrote:
On Tue, 13 Jul 2010 05:14:21 -0700
Zach Pfeffer zpfef...@codeaurora.org wrote:
You mean that you want to specify this alignment attribute every time
you create an IOMMU mapping? Then you can set segment_boundary_mask
On Wed, Jul 14, 2010 at 01:11:49PM -0700, Zach Pfeffer wrote:
If the DMA-API contained functions to allocate virtual space separate
from physical space and reworked how chained buffers functioned it
would probably work - but then things start to look like the VCM API
which does graph based map
On Wed, 14 Jul 2010 13:11:49 -0700
Zach Pfeffer zpfef...@codeaurora.org wrote:
On Wed, Jul 14, 2010 at 10:59:38AM +0900, FUJITA Tomonori wrote:
On Tue, 13 Jul 2010 05:14:21 -0700
Zach Pfeffer zpfef...@codeaurora.org wrote:
You mean that you want to specify this alignment attribute
On Wed, Jul 14, 2010 at 11:05:36PM +0100, Russell King - ARM Linux wrote:
On Wed, Jul 14, 2010 at 01:11:49PM -0700, Zach Pfeffer wrote:
If the DMA-API contained functions to allocate virtual space separate
from physical space and reworked how chained buffers functioned it
would probably
Zach Pfeffer zpfef...@codeaurora.org writes:
On Wed, Jul 14, 2010 at 11:05:36PM +0100, Russell King - ARM Linux wrote:
On Wed, Jul 14, 2010 at 01:11:49PM -0700, Zach Pfeffer wrote:
If the DMA-API contained functions to allocate virtual space separate
from physical space and reworked how
On Wed, Jul 14, 2010 at 06:29:58PM -0700, Zach Pfeffer wrote:
On Wed, Jul 14, 2010 at 11:05:36PM +0100, Russell King - ARM Linux wrote:
On Wed, Jul 14, 2010 at 01:11:49PM -0700, Zach Pfeffer wrote:
If the DMA-API contained functions to allocate virtual space separate
from physical space
On Wed, Jul 14, 2010 at 06:47:34PM -0700, Eric W. Biederman wrote:
Zach Pfeffer zpfef...@codeaurora.org writes:
On Wed, Jul 14, 2010 at 11:05:36PM +0100, Russell King - ARM Linux wrote:
On Wed, Jul 14, 2010 at 01:11:49PM -0700, Zach Pfeffer wrote:
If the DMA-API contained functions to
On Mon, 12 Jul 2010 22:57:06 -0700
Zach Pfeffer zpfef...@codeaurora.org wrote:
FUJITA Tomonori wrote:
On Thu, 08 Jul 2010 16:59:52 -0700
Zach Pfeffer zpfef...@codeaurora.org wrote:
The problem I'm trying to solve boils down to this: map a set of
contiguous physical buffers to an
On Tue, Jul 13, 2010 at 03:03:25PM +0900, FUJITA Tomonori wrote:
On Mon, 12 Jul 2010 22:57:06 -0700
Zach Pfeffer zpfef...@codeaurora.org wrote:
FUJITA Tomonori wrote:
On Thu, 08 Jul 2010 16:59:52 -0700
Zach Pfeffer zpfef...@codeaurora.org wrote:
The problem I'm trying to solve
On Tue, 13 Jul 2010 05:14:21 -0700
Zach Pfeffer zpfef...@codeaurora.org wrote:
You mean that you want to specify this alignment attribute every time
you create an IOMMU mapping? Then you can set segment_boundary_mask
every time you create an IOMMU mapping. It's odd but it should work.
FUJITA Tomonori wrote:
On Thu, 08 Jul 2010 16:59:52 -0700
Zach Pfeffer zpfef...@codeaurora.org wrote:
The problem I'm trying to solve boils down to this: map a set of
contiguous physical buffers to an aligned IOMMU address. I need to
allocate the set of physical buffers in a particular way:
On Thu, 08 Jul 2010 16:59:52 -0700
Zach Pfeffer zpfef...@codeaurora.org wrote:
The problem I'm trying to solve boils down to this: map a set of
contiguous physical buffers to an aligned IOMMU address. I need to
allocate the set of physical buffers in a particular way: use 1 MB
contiguous
Russell King - ARM Linux wrote:
On Wed, Jul 07, 2010 at 03:44:27PM -0700, Zach Pfeffer wrote:
The DMA API handles the allocation and use of DMA channels. It can
configure physical transfer settings, manage scatter-gather lists,
etc.
You're confused about what the DMA API is. You're
On Wed, Jul 07, 2010 at 03:44:27PM -0700, Zach Pfeffer wrote:
The DMA API handles the allocation and use of DMA channels. It can
configure physical transfer settings, manage scatter-gather lists,
etc.
You're confused about what the DMA API is. You're talking about
the DMA engine subsystem
This patch contains the documentation for the API, termed the Virtual
Contiguous Memory Manager. Its use would allow all of the IOMMU to VM,
VM to device and device to IOMMU interoperation code to be refactored
into platform independent code.
Comments, suggestions and criticisms are welcome and
Zach Pfeffer zpfef...@codeaurora.org writes:
This patch contains the documentation for the API, termed the Virtual
Contiguous Memory Manager. Its use would allow all of the IOMMU to VM,
VM to device and device to IOMMU interoperation code to be refactored
into platform independent code.
This patch contains the documentation for the API, termed the Virtual
Contiguous Memory Manager. Its use would allow all of the IOMMU to VM,
VM to device and device to IOMMU interoperation code to be refactored
into platform independent code.
Comments, suggestions and criticisms are welcome and
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