From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1D560C46471 for ; Sun, 5 Aug 2018 21:51:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D2958218F0 for ; Sun, 5 Aug 2018 21:51:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D2958218F0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ucw.cz Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728417AbeHEX55 (ORCPT ); Sun, 5 Aug 2018 19:57:57 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:43088 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726992AbeHEX55 (ORCPT ); Sun, 5 Aug 2018 19:57:57 -0400 Received: by atrey.karlin.mff.cuni.cz (Postfix, from userid 512) id D7FC08063C; Sun, 5 Aug 2018 23:51:50 +0200 (CEST) Date: Sun, 5 Aug 2018 23:51:50 +0200 From: Pavel Machek To: Mikulas Patocka Cc: Andrew Pinski , Richard Earnshaw , ard.biesheuvel@linaro.org, Ramana Radhakrishnan , Florian Weimer , thomas.petazzoni@free-electrons.com, GNU C Library , Catalin Marinas , Will Deacon , linux@armlinux.org.uk, LKML , linux-arm-kernel@lists.infradead.org Subject: Re: framebuffer corruption due to overlapping stp instructions on arm64 Message-ID: <20180805215150.GB1862@amd> References: <9acdacdb-3bd5-b71a-3003-e48132ee1371@redhat.com> <11f9185a-7f71-83df-3a57-0a0ae9c1f934@arm.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="ZfOjI3PrQbgiZnxM" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --ZfOjI3PrQbgiZnxM Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi! > > Can you run the test program on x86 using the similar framebuffer > > setup? Does doing two writes (one aligned and one unaligned but > > overlapping with previous one) cause the same issue? I suspect it > > does, then using memcpy for frame buffers is wrong. I'm pretty sure it will work ok on x86. > Overlapping unaligned writes work on x86 - they have to, because of=20 > backward compatibility. It is not that easy. 8086s (and similar) did not have MTRRs and PATs either. Overlapping unaligned writes _on main memory_, _with normal MTRR settings_ certainly work ok on x86. Chances is memory type can be configured to work similar way on your ARM/PCIe case? > 8086, 80286 and 80386 didn't have any cache at all. 386s had cache (but not on die). Pavel --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html --ZfOjI3PrQbgiZnxM Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAltncXYACgkQMOfwapXb+vLjnACgviHS0QA96XvspC2s/b9nRkCR K4cAoKc484UBeHoiMMGsNdgqoeaO8ADS =xTyZ -----END PGP SIGNATURE----- --ZfOjI3PrQbgiZnxM-- From mboxrd@z Thu Jan 1 00:00:00 1970 From: pavel@ucw.cz (Pavel Machek) Date: Sun, 5 Aug 2018 23:51:50 +0200 Subject: framebuffer corruption due to overlapping stp instructions on arm64 In-Reply-To: References: <9acdacdb-3bd5-b71a-3003-e48132ee1371@redhat.com> <11f9185a-7f71-83df-3a57-0a0ae9c1f934@arm.com> Message-ID: <20180805215150.GB1862@amd> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi! > > Can you run the test program on x86 using the similar framebuffer > > setup? Does doing two writes (one aligned and one unaligned but > > overlapping with previous one) cause the same issue? I suspect it > > does, then using memcpy for frame buffers is wrong. I'm pretty sure it will work ok on x86. > Overlapping unaligned writes work on x86 - they have to, because of > backward compatibility. It is not that easy. 8086s (and similar) did not have MTRRs and PATs either. Overlapping unaligned writes _on main memory_, _with normal MTRR settings_ certainly work ok on x86. Chances is memory type can be configured to work similar way on your ARM/PCIe case? > 8086, 80286 and 80386 didn't have any cache at all. 386s had cache (but not on die). Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 181 bytes Desc: Digital signature URL: