From owner-freebsd-hackers@freebsd.org Sun Nov 8 12:00:15 2015 Return-Path: Delivered-To: freebsd-hackers@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 61E13A29987 for ; Sun, 8 Nov 2015 12:00:15 +0000 (UTC) (envelope-from deco33000@yandex.com) Received: from forward12j.cmail.yandex.net (forward12j.cmail.yandex.net [IPv6:2a02:6b8:0:1630::b2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "forwards.mail.yandex.net", Issuer "Certum Level IV CA" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 1D56B158B for ; Sun, 8 Nov 2015 12:00:15 +0000 (UTC) (envelope-from deco33000@yandex.com) Received: from web20j.yandex.ru (web20j.yandex.ru [5.45.198.61]) by forward12j.cmail.yandex.net (Yandex) with ESMTP id 8B0C120D21; Sun, 8 Nov 2015 15:00:03 +0300 (MSK) Received: from 127.0.0.1 (localhost [127.0.0.1]) by web20j.yandex.ru (Yandex) with ESMTP id E049221C0B95; Sun, 8 Nov 2015 15:00:02 +0300 (MSK) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex.com; s=mail; t=1446984003; bh=Fg0ytSzGxOx9CPEkXEbD/kTndirVGdJpyrG/V2xmvNQ=; h=From:To:In-Reply-To:References:Subject:Date; b=JMSKchfPD64ajU7/gu1rzz/xVkCjlsiZ8+ePoJEbS/4LPie65LRx8/en5z7ajSGnI mbnA95F0mQMpjKcDl2ol/YeTYahNOGp1FhxfcU+Wp3zDcbEOKm6pyX2r7be+k2u/Qw vcIT+aGtxzm6+bd5nJ88aaKsqq4ziNGrHUVacqak= Received: by web20j.yandex.ru with HTTP; Sun, 08 Nov 2015 15:00:02 +0300 From: AlexHully To: Hans Petter Selasky , "freebsd-hackers@freebsd.org" In-Reply-To: <563F38DD.5070409@selasky.org> References: <298361446978177@web22g.yandex.ru> <563F38DD.5070409@selasky.org> Subject: Re: dma MIME-Version: 1.0 Message-Id: <373471446984002@web20j.yandex.ru> X-Mailer: Yamail [ http://yandex.ru ] 5.0 Date: Sun, 08 Nov 2015 13:00:02 +0100 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=koi8-r X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 08 Nov 2015 12:00:15 -0000 Ok, those were recent? --š Alex 08.11.2015, 12:56, "Hans Petter Selasky" : > On 11/08/15 11:22, AlexHully wrote: >> šHi, >> >> šI would like a clarification for dma. >> >> šThe context: most dma capable devices have 32 bits address range. >> šIs it correct that, if there was no 3G/1G mapping in the kernel, or that kernel low memory could map 4Gb memory, one could choose any free addresses in that low memory to set up a dma buffer? >> >> šThat would avoid all the mapping hassle, and performance cost associated. > > I've seen USB controllers only supporting 2G address range. > > --HPS