From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: Re: Improving hvm IO performance by using self IO emulator (YA io-emu?) Date: Fri, 23 Feb 2007 12:56:00 -0600 Message-ID: <45DF38C0.20500@us.ibm.com> References: <20070222052309.GA2764@saphi> <45DDBF76.1030805@us.ibm.com> <1172177938.45de041286155@imp.free.fr> <200702222124.16755.mark.williamson@cl.cam.ac.uk> <45DE0C21.20605@us.ibm.com> <20070223002628.4182db2d@lxorguk.ukuu.org.uk> <45DE317F.6020106@us.ibm.com> <20070223125744.3c523661@lxorguk.ukuu.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20070223125744.3c523661@lxorguk.ukuu.org.uk> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Alan Cc: tgingold@free.fr, xen-devel@lists.xensource.com, Mark Williamson List-Id: xen-devel@lists.xenproject.org Alan wrote: >> But it isn't supported by older kernels and most versions of Windows. A >> > > Linux 2.4.x AHCI drivers exist. Windows 95/98 are lacking them as is NT > that much is true, but Win2K and later support AHCI. AHCI is also very > nice from a virtualisation point of view as you get commands in queues > and you can batch them up sensibly. > > For older windows there is the ADMA interface which is saner to emulate > than SFF but not very sane. > > >> This discussion is independent of Xen. It's equally applicable to KVM >> and QEMU so please don't assume this has anything to do with Xen's merge >> status. >> > > Don't even get me started on qemu. The qemu "emulation" of ATAPI is a good > reason to use anything else as an interface. > Feel free to submit patches. Regards, Anthony Liguori > Alan >