From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: How to disable IDE DMA in KVM or in guest OS Date: Thu, 15 May 2014 08:58:04 +0200 Message-ID: <5374657C.7030007@web.de> References: <5374613F.3060704@web.de> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="2khqbbKiTru2mnrTsRS8g3O6FlqMK14wN" Cc: kvm To: Arthur Chunqi Li Return-path: Received: from mout.web.de ([212.227.15.14]:52992 "EHLO mout.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751605AbaEOG6M (ORCPT ); Thu, 15 May 2014 02:58:12 -0400 In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --2khqbbKiTru2mnrTsRS8g3O6FlqMK14wN Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 2014-05-15 08:55, Arthur Chunqi Li wrote: > On Thu, May 15, 2014 at 2:39 PM, Jan Kiszka wrote: >> On 2014-05-15 07:54, Arthur Chunqi Li wrote: >>> Hi Jan and there, >>> >>> I want to disable IDE BMDMA in Qemu/KVM and let guest OS uses only PI= O >>> mode. Are there any configurations in Qemu or KVM to disable the >>> hardware support of DMA? >> >> Not that I know. These features are built into the chipsets we emulate= , >> and there seems to be no option to disable them. Maybe the isapc will >> not expose DMA capabilities - but will also lack a lot of other things= >> like PCI... >=20 > Well, if I boot guest Linux with ide-core.nodma=3D0.0 libata.dma=3D0 > ide=3Dnodma ide0=3Dnodma, why are bmdma irqs (14 and 15) also triggered= ? I > think guest OS should only use PIO in this situation. To signal data availability e.g.? It's up to the guest driver if it makes use of asynchronous notifications or polls for this. Jan --2khqbbKiTru2mnrTsRS8g3O6FlqMK14wN Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iEYEARECAAYFAlN0ZX0ACgkQitSsb3rl5xQMgACghJtQUVbSkFNnF9dzE8ttoYo7 2G8AnRbEFovZIuIXf2R0RjCldYdweIF8 =W3gz -----END PGP SIGNATURE----- --2khqbbKiTru2mnrTsRS8g3O6FlqMK14wN--