From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56091) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Yaqkg-0000Ma-En for qemu-devel@nongnu.org; Wed, 25 Mar 2015 15:14:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Yaqkd-00042c-8F for qemu-devel@nongnu.org; Wed, 25 Mar 2015 15:14:06 -0400 Received: from smtp2-g21.free.fr ([212.27.42.2]:14400) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Yaqkd-00042I-2C for qemu-devel@nongnu.org; Wed, 25 Mar 2015 15:14:03 -0400 Message-ID: <5513083D.30008@reactos.org> Date: Wed, 25 Mar 2015 20:10:53 +0100 From: =?UTF-8?B?SGVydsOpIFBvdXNzaW5lYXU=?= MIME-Version: 1.0 References: <1425593606-5909-1-git-send-email-hpoussin@reactos.org> <1425593606-5909-2-git-send-email-hpoussin@reactos.org> <5512CA20.7040305@redhat.com> In-Reply-To: <5512CA20.7040305@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH 1/8] rc4030: create custom DMA address space List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini , qemu-devel@nongnu.org Cc: Leon Alrae , Laurent@Vivier.EU, Aurelien Jarno Le 25/03/2015 15:45, Paolo Bonzini a =C3=A9crit : > > > On 05/03/2015 23:13, Herv=C3=A9 Poussineau wrote: >> Add a new memory region in system address space where DMA address spac= e >> definition (the 'translation table') belongs, so we can update on the = fly >> the DMA address space. >> >> Signed-off-by: Herv=C3=A9 Poussineau > > Would it make sense to just use an IOMMU region for the DMA address spa= ce? I don't really know. Currently, the first user is the dp8393x network car= d (a sysbus device), which is connected through the DMA address space. It means that *every* read or write access needs to be translated, even t= hose accessing 1 or 2 bytes. dp8393x has no direct connection to the syst= em memory. On some other machines, like the m68k Quadra 800, the dp8393x is only con= nected to the system memory. A second user is the ESP SCSI card in DMA mode, using the DMA address spa= ce with the help of the DMA controller. As DMA address space mapping doesn't change much (except initialization p= hases), and that it is used for small (1 or 2 bytes) and big transfers (n= etwork packets and disk accesses), I thought that an=20 address space was better. Herv=C3=A9