From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id 618746B0095 for ; Wed, 23 Nov 2011 16:17:14 -0500 (EST) Received: by vcbfk26 with SMTP id fk26so2424412vcb.14 for ; Wed, 23 Nov 2011 13:17:12 -0800 (PST) References: <9AF7658D-FEDB-479A-8D4F-A54264363CB4@gmail.com> In-Reply-To: Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: text/plain; charset=utf-8 Message-Id: Content-Transfer-Encoding: quoted-printable From: Jean-Francois Dagenais Subject: Re: use of alloc_bootmem for a PCI-e device Date: Wed, 23 Nov 2011 16:21:15 -0500 Sender: owner-linux-mm@kvack.org List-ID: To: Michal Nazarewicz Cc: linux-mm@kvack.org On Nov 23, 2011, at 14:31, Michal Nazarewicz wrote: > On Wed, 23 Nov 2011 20:30:30 +0100, Jean-Francois Dagenais = wrote: >> I am maintaining a kernel for an embedded product. We have an FPGA >> acquisition device interfaced through PCI-e on different intel = platforms. >> The acquisition device needs an extra large physically contiguous = memory >> area to autonomously dump acquired data into. >=20 > [...] >=20 >> We are doing another incarnation of the product on an Atom E6xx which = has >> no such IOMMU and am looking into ways of allocating a huge chunk of = ram. >> Kind of like integrated gfx chips do with RAM, but I don't have the = assistance >> of the BIOS. >=20 > One trick that you might try to use (even though it's a bit hackish) = is to > pass ram=3D### on Linux command line where the number passed is actual = memory > minus size of the buffer you need. Other then that, you might take a = look > at CMA (CMAv17 it was sent last week or so to linux-mm) which in one = of the > initialisation steps needs to grab memory regions. Thanks for that, I am looking into it. Looks like it can do what I want. Are there any mainline merge plans? Unless I am mistaken, because of SWIOTLB, only x86_32 is supported, = correct? Since I want to allocate the buffer once at startup, then keep it until = shutdown, can you suggest a simpler, less flexible alternative? (other than the = boot args method which I consider a fallback plan). >=20 > --=20 > Best regards, _ _ > .o. | Liege of Serenely Enlightened Majesty of o' \,=3D./ `o > ..o | Computer Science, Micha=C5=82 =E2=80=9Cmina86=E2=80=9D = Nazarewicz (o o) > ooo +------------------ooO--(_)--Ooo-- Thanks for helping!= -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org