From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx104.postini.com [74.125.245.104]) by kanga.kvack.org (Postfix) with SMTP id E5B5E6B0002 for ; Mon, 4 Mar 2013 05:33:10 -0500 (EST) Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01CE18C3.A9C11EC8" Subject: how to acquire large DMA buffes in 64bit kernel Date: Mon, 4 Mar 2013 11:33:08 +0100 Message-ID: From: =?iso-8859-2?Q?Uro=B9_Golob?= Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: =?iso-8859-2?Q?Uro=B9_Golob?= This is a multi-part message in MIME format. ------_=_NextPart_001_01CE18C3.A9C11EC8 Content-Type: text/plain; charset="iso-8859-2" Content-Transfer-Encoding: quoted-printable Hello fellow developers, I am researching possibilities to acquire large DMA contiguous memory = for our new device. Plan is to develop Linux driver for our new product = with MicroTCA Kontron board with Intel i7 and 4GB ram (there is slim = possibility to get 8GB system). In the same system (crate) user could = plug in up to 10 custom devices (that is our new product with fpga chip = and pcie interface), each board requires 4 32MB buffers in kernel = module. So on end of day I would like to have from 128 to 1280MB of = memory, depends of number of devices plugged into system. I know that it = is possible to use scatter gather for DMA, but there is shortage of = descriptors in our fpga chip... I have come to some problems/questions and I can't find answer to, I did = use google and read ton of documentation, books, forums, etc... with no = luck... - Does Contiguous Memory Allocator support x86_64 platform? And if, how = to configure kernel ( because there is conflict between SWIOTLB and = HAVE_DMA_CONTIGOUS).=20 - Is there any working bigphysarea patch for Linux kernel 3.2.x (or = newer) for x86_64 platform (I know that there is for x86_32, but wit 32 = bit kernel I could get only 512MB of contiguous memory). I must confess I am total noob in device driver development, so what am = I missing? Is there any other way to acquire large buffers in Linux = kernel module? Am I just way too greedy with contiguous memory? Best regards, Uros ------_=_NextPart_001_01CE18C3.A9C11EC8 Content-Type: text/html; charset="iso-8859-2" Content-Transfer-Encoding: quoted-printable how to acquire large DMA buffes in 64bit kernel

Hello fellow developers,
 I am researching possibilities to acquire large DMA contiguous = memory for our new device. Plan is to develop Linux driver for our new = product with MicroTCA Kontron board with Intel i7 and 4GB ram (there is = slim possibility to get 8GB system). In the same system (crate) user = could plug in up to 10 custom devices (that is our new product with fpga = chip and pcie interface), each board requires 4 32MB buffers in kernel = module. So on end of day I would like to have from 128 to 1280MB of = memory, depends of number of devices plugged into system. I know that it = is possible to use scatter gather for DMA, but there is shortage of = descriptors in our fpga chip...
I have come to some problems/questions and I can't find answer to, I did = use google and read ton of documentation, books, forums, etc... with no = luck...

 - Does Contiguous Memory Allocator support x86_64 platform? And = if, how to configure kernel ( because there is conflict between SWIOTLB = and HAVE_DMA_CONTIGOUS).
 - Is there any working bigphysarea patch for Linux kernel 3.2.x = (or newer) for x86_64 platform (I know that there is for x86_32, but wit = 32 bit kernel I could get only 512MB of contiguous memory).

I must confess I am total noob in device driver development, so what am = I missing? Is there any other way to acquire large buffers in Linux = kernel module? Am I just way too greedy with contiguous memory?

Best regards,

Uros

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