From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from outbound7-dub-R.bigfish.com (outbound-dub.frontbridge.com [213.199.154.16]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "*.bigfish.com", Issuer "*.bigfish.com" (not verified)) by ozlabs.org (Postfix) with ESMTPS id D5783DDF0C for ; Wed, 21 May 2008 07:26:28 +1000 (EST) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Subject: RE: Instruction OCM Date: Tue, 20 May 2008 14:26:15 -0700 In-reply-to: <200805201511.25957.temerkhanov@yandex.ru> References: <012401c8b9c3$74b947c0$5e2bd740$@com> <4831CCA2.6000107@yandex.ru><016b01c8ba5a$9a621000$cf263000$@com> <200805201511.25957.temerkhanov@yandex.ru> From: "Stephen Neuendorffer" To: , "mojtaba" , , "Grant Likely" Message-Id: <20080520212616.B378E3A006D@mail99-dub.bigfish.com> List-Id: Linux on Embedded PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Ah yes, I forgot about that little detail with the OCM. It would be slick if these mappings were generated based on memory nodes in the device tree for ARCH=3Dpowerpc. Steve > -----Original Message----- > From: linuxppc-embedded-bounces+stephen=3Dneuendorffer.name@ozlabs.org [mailto:linuxppc-embedded- > bounces+stephen=3Dneuendorffer.name@ozlabs.org] On Behalf Of Temerkhanov > Sent: Tuesday, May 20, 2008 4:11 AM > To: mojtaba; linuxppc-embedded@ozlabs.org > Subject: Re: Instruction OCM > = > On Tuesday 20 May 2008 13:19:26 mojtaba wrote: > > Thank you for your email. But what is the solution to that? I have seen > > this in a thesis: > > > > "when using the OCM buses to connect memory, we can only use virtual memory > > as long as the virtual address is the same as the physical address, which > > is conceptually > > the same as using a system without MMU. Therefore porting Linux to a > > system based on an OCM memory system is not possible" > > > > http://ce.et.tudelft.nl/publicationfiles/1367_700_thesis.pdf > > > > Is that right? What do you suggest? > > > = > = > Getting OCM-based devices (and even memory) to work in Linux is possible. All > you need is to setup a mapping with virtual addresses equal to physical (some > info can be found here: > http://courses.ece.uiuc.edu/ece412/MP_Files/mp2/20060623-XUP-Linux-Tutor ial-REVISION-FINAL.pdf) > = > Furthermore, if you really need to get the code running from OCM, I'd suggest > to setup such MMU mapping for OCM region very early - it can be done in > initial_mmu function at head_4xx.S. Look at line 936 (#if > defined(CONFIG_SERIAL_TEXT_DEBUG) && defined(SERIAL_DEBUG_IO_BASE)) > - that's very good point to start. > = > Regards, Sergey Temerkhanov > _______________________________________________ > Linuxppc-embedded mailing list > Linuxppc-embedded@ozlabs.org > https://ozlabs.org/mailman/listinfo/linuxppc-embedded This email and any attachments are intended for the sole use of the named r= ecipient(s) and contain(s) confidential information that may be proprietary= , privileged or copyrighted under applicable law. If you are not the intend= ed recipient, do not read, copy, or forward this email message or any attac= hments. Delete this email message and any attachments immediately.