From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH 11/14] ARM: v6k: use CPU domain feature if we include support for arch < ARMv6K Date: Fri, 28 Jan 2011 08:49:44 -0800 Message-ID: <20110128164944.GT23412@atomide.com> References: <20110127185935.GA1651@n2100.arm.linux.org.uk> <1296207966.1799.10.camel@e102109-lin.cambridge.arm.com> <20110128095953.GA13005@n2100.arm.linux.org.uk> <1296211611.1799.15.camel@e102109-lin.cambridge.arm.com> <20110128110629.GB13005@n2100.arm.linux.org.uk> <1296217518.1799.59.camel@e102109-lin.cambridge.arm.com> <20110128132134.GD13005@n2100.arm.linux.org.uk> <1296227465.1799.95.camel@e102109-lin.cambridge.arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mho-02-ewr.mailhop.org ([204.13.248.72]:27424 "EHLO mho-02-ewr.mailhop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754883Ab1A1QuC (ORCPT ); Fri, 28 Jan 2011 11:50:02 -0500 Content-Disposition: inline In-Reply-To: <1296227465.1799.95.camel@e102109-lin.cambridge.arm.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Catalin Marinas Cc: Russell King - ARM Linux , linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org * Catalin Marinas [110128 07:11]: > On Fri, 2011-01-28 at 13:21 +0000, Russell King - ARM Linux wrote: > > On Fri, Jan 28, 2011 at 12:25:18PM +0000, Catalin Marinas wrote: > > > With your latest patches, do we use the TLS emulation on ARMv7 (UP) if > > > v6 is compiled in? If that's the case, we may have a problem - I talked > > > to the toolchain guys and it looks like code optimised for ARMv7 reads > > > the TLS register directly without going through the kuser helper. So you > > > may have people taking an Ubuntu filesystem (v7 only) and a pre-built > > > OMAP image with TLS emulation even on Cortex-A8 and things won't work as > > > expected. > > > > You're really making a mountain out of TLS. > > Not really, just asking for clarification as I haven't checked all your > patches recently. > > > If we have a v6+v6k+v7 kernel, then the way the kernel TLS code is built, > > we will use the TLS register if that's available on the hardware. If it > > isn't, we will write the TLS value directly to virtual 0xffff0ffc. > > > > So, a kernel built for v6+v6k+v7, when run on v7, will set the hardware > > TLS register, and your v7 optimized binaries which access the TLS register > > directly will work. Same for v6k. > > Great. Yes AFAIK we sorted out the TLS issue already a while back for v6+v6k+v7. Regards, Tony From mboxrd@z Thu Jan 1 00:00:00 1970 From: tony@atomide.com (Tony Lindgren) Date: Fri, 28 Jan 2011 08:49:44 -0800 Subject: [PATCH 11/14] ARM: v6k: use CPU domain feature if we include support for arch < ARMv6K In-Reply-To: <1296227465.1799.95.camel@e102109-lin.cambridge.arm.com> References: <20110127185935.GA1651@n2100.arm.linux.org.uk> <1296207966.1799.10.camel@e102109-lin.cambridge.arm.com> <20110128095953.GA13005@n2100.arm.linux.org.uk> <1296211611.1799.15.camel@e102109-lin.cambridge.arm.com> <20110128110629.GB13005@n2100.arm.linux.org.uk> <1296217518.1799.59.camel@e102109-lin.cambridge.arm.com> <20110128132134.GD13005@n2100.arm.linux.org.uk> <1296227465.1799.95.camel@e102109-lin.cambridge.arm.com> Message-ID: <20110128164944.GT23412@atomide.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org * Catalin Marinas [110128 07:11]: > On Fri, 2011-01-28 at 13:21 +0000, Russell King - ARM Linux wrote: > > On Fri, Jan 28, 2011 at 12:25:18PM +0000, Catalin Marinas wrote: > > > With your latest patches, do we use the TLS emulation on ARMv7 (UP) if > > > v6 is compiled in? If that's the case, we may have a problem - I talked > > > to the toolchain guys and it looks like code optimised for ARMv7 reads > > > the TLS register directly without going through the kuser helper. So you > > > may have people taking an Ubuntu filesystem (v7 only) and a pre-built > > > OMAP image with TLS emulation even on Cortex-A8 and things won't work as > > > expected. > > > > You're really making a mountain out of TLS. > > Not really, just asking for clarification as I haven't checked all your > patches recently. > > > If we have a v6+v6k+v7 kernel, then the way the kernel TLS code is built, > > we will use the TLS register if that's available on the hardware. If it > > isn't, we will write the TLS value directly to virtual 0xffff0ffc. > > > > So, a kernel built for v6+v6k+v7, when run on v7, will set the hardware > > TLS register, and your v7 optimized binaries which access the TLS register > > directly will work. Same for v6k. > > Great. Yes AFAIK we sorted out the TLS issue already a while back for v6+v6k+v7. Regards, Tony