From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Brownell Subject: Re: FOR COMMENT: void __iomem * and similar casts are Bad News Date: Wed, 3 Sep 2008 14:18:44 -0700 Message-ID: <200809031418.44929.david-b@pacbell.net> References: <20080827220821.GE7227@flint.arm.linux.org.uk> <20080903193421.GC19980@flint.arm.linux.org.uk> <13B9B4C6EF24D648824FF11BE8967162036545FAD7@dlee02.ent.ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from smtp115.sbc.mail.sp1.yahoo.com ([69.147.64.88]:39890 "HELO smtp115.sbc.mail.sp1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752293AbYICVSr (ORCPT ); Wed, 3 Sep 2008 17:18:47 -0400 In-Reply-To: <13B9B4C6EF24D648824FF11BE8967162036545FAD7@dlee02.ent.ti.com> Content-Disposition: inline Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: "Woodruff, Richard" Cc: Russell King - ARM Linux , Tony Lindgren , "linux-omap@vger.kernel.org" , Eduardo Valentin On Wednesday 03 September 2008, Woodruff, Richard wrote: > Fixed translations do have some benefits. =A0You can ensure that you > are using section or super section descriptors to cover large areas. > This does result in better TLB usage. =A0Along with freeing up TLB > entries you also generally avoid TLB misses on IO calls which > touch a variety of internal spaces as part of the IRQ sequence. =20 =2E.. which is exactly why some linux/arch/... code makes sure ioremap(= ) can return fixed mappings instead of always requiring dynamic ones. > Frankly I've never been convinced that a multi OMAP1/2/3 image makes = much > sense apart forcing better code structure Which is actually a pretty big thing. Along with "structure", it helps avoid #define collisions ... and also ensures that test builds can cover increasing fractions of the code base, giving a big win for maintainability. Maintainability is a *big thing* ... without it, you ensure that lots of code will begin bitrotting long before it needs to. > and being kind of cool. =A0Each=20 > chip has very different performance targets and is really better buil= t with > an optimized tool chain (ARMv5, ARMv6, ARMv7). =A0Doing multi-boots w= ith in > the same architecture family seems really good but across seems less = so. True enough, but that decision can be in the hands of whoever builds a kernel. If you want to deploy an A8-optimized system, the kernel will be only one part of the equation. - Dave -- To unsubscribe from this list: send the line "unsubscribe linux-omap" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html