From owner-svn-src-head@freebsd.org Wed Dec 28 13:47:03 2016 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id E646AC4F53D; Wed, 28 Dec 2016 13:47:03 +0000 (UTC) (envelope-from kabaev@gmail.com) Received: from mail-qk0-x242.google.com (mail-qk0-x242.google.com [IPv6:2607:f8b0:400d:c09::242]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 9D8DA1D74; Wed, 28 Dec 2016 13:47:03 +0000 (UTC) (envelope-from kabaev@gmail.com) Received: by mail-qk0-x242.google.com with SMTP id t184so32182583qkd.1; Wed, 28 Dec 2016 05:47:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:in-reply-to:references :mime-version; bh=zQZDIPvTWblW6andBDHU5gLMBM8ZL1HkY5OdVOPUHOg=; b=ID2D8osL2JPLGnZ7U+tUck2BvS8PyWCBylQRe5innN2wiR0Ce4YXz+fOP57PW2vN47 atb/Zmep2l25cLUFMiDBxoCIISVe+Xz1ZfAmMLWtLny1UvnJBwqL3XpJef3BisG5E26D 2vUUm8Eh5edXGJldUtWGmg8YmBZGJHdstMY88wQPdxP3Wp8feo0UoS0JEk7r2n7+Yuno vX6tsDaKs8IIfcpHGfzZsJB2dqDGz7nbbhB2JDC9+DNLQXa0yF7HoQqGJmTVBEE8+J5b CcGT8vlPoYhTZaaIP6vu399wgqRbpjEzrQFKdND2DcsZE0UKZ/e+gScZe1hExNKxcABQ 3eLg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version; bh=zQZDIPvTWblW6andBDHU5gLMBM8ZL1HkY5OdVOPUHOg=; b=dksosO451doLRz0bQ0nbNYqBN7492ErJTWCp/MM1RXewp0iPdkAAdbXWcctj/EWBxh Q7MQIX0Lpw3jj9Ydc1RGNixi7P2B88WiAiOpIXRFAGnc7J2hVfYAQGe87ht6sNfsXSxB Eeo4JqYoK3PBi9RuVrw6BNUNLxnt/cscBtScUklxHDQrM0xMOTJfk+ZFoe5p2sa1d6i7 THv6zkV6bvWa8bVcoPS7mHPb4QcA7FM4A/P27wsKwyAdblRtg/O9h6cbaAhciTqOiV1T jM9Bg24bRBSY48mBcN0jdxddU6U3zlTVFUl9OAECwlSrdt9GDR6Ti+RSvXVJY/e6ZvsC UhnQ== X-Gm-Message-State: AIkVDXIEzjjSrrYyB4tHYYiEFhXtdL5N++MzGfu3mX1Sl5Rpgptb/dcQGcW/726TA4RYaQ== X-Received: by 10.55.95.1 with SMTP id t1mr34991611qkb.277.1482932822847; Wed, 28 Dec 2016 05:47:02 -0800 (PST) Received: from kan ([2601:18f:802:4680:226:18ff:fe00:232e]) by smtp.gmail.com with ESMTPSA id p19sm30820689qtp.4.2016.12.28.05.47.01 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 28 Dec 2016 05:47:02 -0800 (PST) Date: Wed, 28 Dec 2016 08:46:53 -0500 From: Alexander Kabaev To: Adrian Chadd Cc: Alexander Kabaev , "src-committers@freebsd.org" , "svn-src-all@freebsd.org" , "svn-src-head@freebsd.org" Subject: Re: svn commit: r310650 - in head/sys/mips: include mips Message-ID: <20161228084653.0326caa4@kan> In-Reply-To: References: <201612280255.uBS2tQeR045512@repo.freebsd.org> X-Mailer: Claws Mail 3.14.1 (GTK+ 2.24.29; amd64-portbld-freebsd12.0) MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; boundary="Sig_/y/NNRm+pci6OV9c.3sVTdHg"; protocol="application/pgp-signature" X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 28 Dec 2016 13:47:04 -0000 --Sig_/y/NNRm+pci6OV9c.3sVTdHg Content-Type: text/plain; charset=KOI8-R Content-Transfer-Encoding: quoted-printable On Tue, 27 Dec 2016 21:50:32 -0800 Adrian Chadd wrote: > hiya, >=20 > so I dug into the mips24k definition of this. It says this: >=20 > " > 3.4.3 Uncached accelerated writes > The 24K core permits memory regions to be marked as "uncached > accelerated". This type of region is useful to hard- > ware which is "write only" - perhaps video frame buffers, or some > other hardware stream. Sequential word stores in > such regions are gathered into cache-line-sized chunks, before being > written with a single burst cycle on the CPU > interface. > Such regions are uncached for read, and partial-word or > out-of-sequence writes have "unpredictable" effects - don't > do them. The burst write is normally performed when software writes to > the last location in the memory block or does > an uncached-accelerated write to some other block; but it can also be > triggered by a > sync instruction, a pref nudge, a matching load or any exception. If > the block is not completely written by the time it's pushed out, it > will be written using a series of doubleword or smaller write cycles > over the 24K core's 64-bit memory interface. > " >=20 > So, question is - is our write combining page attribute in the VM > suitable for this? Is it defined as "only do full sequential word > writes"? Or do we risk having some other platform use it in a less > "don't do this" way and then MIPS is the one at fault again? :) >=20 >=20 > -adrian >=20 >=20 FWIW, this is more or less standard verbiage for memory mapped devices and devices is where one would expect framebuffer to reside, so I would not read too much into it. I committed change that does not map UA to WC unconditionally and will let people who need write combining to enable it on a case by case basis. For now, only Ingenic XBursts are doing so as these are ones I have tested. --=20 Alexander Kabaev --Sig_/y/NNRm+pci6OV9c.3sVTdHg Content-Type: application/pgp-signature Content-Description: Цифровая подпись OpenPGP -----BEGIN PGP SIGNATURE----- iQKTBAEBCgB9FiEExffZlZm2QeE8UVaRBxMimZJ5Ln4FAlhjwk1fFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldEM1 RjdEOTk1OTlCNjQxRTEzQzUxNTY5MTA3MTMyMjk5OTI3OTJFN0UACgkQBxMimZJ5 Ln4O9A/+Ll0BXYm9sUys0R9sxrnrMOTouq+vOB5VCkkx7ztmTuRVX9WaXe51q7T+ e0gRcvr61jViiF+aFJFWEjCWKjkO1jcnSKB3X1Mtz5gy/hiLRnxhdIRlh4DMsQAn Az+KtM1ozixIHaohU2ARQvL+rt/vHkaDng6wwtZ9xnbajNcMeXArXlRBCnzl6mCN igDQo3/i7v7ZcsoufYegsQo87lV/iLPOo4PpStBJxL2IDl9lSXJxY80twRGGRHFt V6rRVRdQbeHYYvg5eNBpXZL209CgChvatSOyqqU97sIsA39ozFV9j1AG4GVrD5+p CGBUvOYE76a8VL7xXAHpipOlNn9dS+bT9MmzB4czYgcUDtySOuYksOKSWilkjNSn ARYVY2AIJpId14mN94qjs3o08QpHzMb53tteRgLTRapgoCct5Je/gAeq0FPaFcBk TnjVAXzLQ5SxBQkLZklJ/VHV8h2NUGWms5jhDF0DHZojPpk/FmBHXRhY41GVNRas P99gZX0LOKH+i4y3njDzbw3FANL53lJUyZxCTvAYV5mq3HbLQDZYeL+OrPWSIO+H DE+gqawrLvJA4JLlwWV/Wx93jTM95I+qbMZaUk9Dn3BbAeeHP31W9fWRtW/qCKaj 5QIV4IzWZULG858cP/Aty7201kA53LJPPDzUCPpLB6y5Q6+VYeo= =PSbE -----END PGP SIGNATURE----- --Sig_/y/NNRm+pci6OV9c.3sVTdHg--