From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: vexpress: Framebuffer broken with KVM enabled Date: Mon, 16 Feb 2015 10:26:07 +0100 Message-ID: <54E1B7AF.5020905@web.de> References: <54E1B4BA.3030705@web.de> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="F50hHlIvTWl1kr8t0gE6o5sljwPkAiA2s" Cc: qemu-devel , kvmarm , kvm To: Anup Patel Return-path: Received: from mout.web.de ([212.227.15.4]:53882 "EHLO mout.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932069AbbBPJ0N (ORCPT ); Mon, 16 Feb 2015 04:26:13 -0500 In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --F50hHlIvTWl1kr8t0gE6o5sljwPkAiA2s Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 2015-02-16 10:20, Anup Patel wrote: > On Mon, Feb 16, 2015 at 2:43 PM, Jan Kiszka wrote: >> Hi, >> >> next issue related to KVM/QEMU on the TK1: The guest image I'm running= >> gives proper framebuffer output when in emulation mode. Once KVM is >> enabled, the screen is - at best - only initially updated. Sometimes I= >> see the famous tux images and a bit of the console texts, but usually = it >> stays black. Explanations? >=20 > The QEMU accesses Guest Video RAM (or any portion of Guest RAM) as > cacheable user space memory. The Guest Kernel might access Guest Video > RAM as non-cacheable to maintain coherency with video device. If this i= s > the case then all updates by Guest kernel to Guest Video RAM will not > be visible to QEMU. On x86, we manage such RAM as coalesced MMIO region, sync'ing it periodically or on specific register accesses into the video card model. I suppose there is nothing like this for the pl111 yet, right? Jan --F50hHlIvTWl1kr8t0gE6o5sljwPkAiA2s 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 iEYEARECAAYFAlTht7AACgkQitSsb3rl5xRngACeJ895k5eZaZma6NrJ4eJWMF7d akcAoIrcmsvFR0kvVz2cq8dw4V4V6/m8 =MZ/1 -----END PGP SIGNATURE----- --F50hHlIvTWl1kr8t0gE6o5sljwPkAiA2s--