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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E4025C433FE for ; Fri, 6 May 2022 13:15:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1392284AbiEFNSr (ORCPT ); Fri, 6 May 2022 09:18:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38696 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343648AbiEFNSp (ORCPT ); Fri, 6 May 2022 09:18:45 -0400 Received: from angie.orcam.me.uk (angie.orcam.me.uk [IPv6:2001:4190:8020::34]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 8E7F962A32; Fri, 6 May 2022 06:15:02 -0700 (PDT) Received: by angie.orcam.me.uk (Postfix, from userid 500) id F116B9200B4; Fri, 6 May 2022 15:15:00 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by angie.orcam.me.uk (Postfix) with ESMTP id ED3C892009E; Fri, 6 May 2022 14:15:00 +0100 (BST) Date: Fri, 6 May 2022 14:15:00 +0100 (BST) From: "Maciej W. Rozycki" To: David Laight cc: Arnd Bergmann , Rich Felker , "open list:IA64 (Itanium) PLATFORM" , "open list:SUPERH" , Catalin Marinas , Dave Hansen , "open list:MIPS" , "James E.J. Bottomley" , "open list:SPARC + UltraSPARC (sparc/sparc64)" , "open list:RISC-V ARCHITECTURE" , Will Deacon , linux-arch , Yoshinori Sato , Helge Deller , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Russell King , Ingo Molnar , Geert Uytterhoeven , linux-pci , Bjorn Helgaas , Matt Turner , Albert Ou , Arnd Bergmann , Niklas Schnelle , "open list:M68K ARCHITECTURE" , Ivan Kokshaysky , Paul Walmsley , Thomas Gleixner , "moderated list:ARM PORT" , Richard Henderson , Michal Simek , Thomas Bogendoerfer , "open list:PARISC ARCHITECTURE" , Greg Kroah-Hartman , Linux Kernel Mailing List , Palmer Dabbelt , "open list:ALPHA PORT" , Borislav Petkov , "open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)" , "David S. Miller" Subject: RE: [RFC v2 01/39] Kconfig: introduce HAS_IOPORT option and select it as necessary In-Reply-To: <5239892986c94239a122ab2f7a18a7a5@AcuMS.aculab.com> Message-ID: References: <20220505161028.GA492600@bhelgaas> <5239892986c94239a122ab2f7a18a7a5@AcuMS.aculab.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org On Fri, 6 May 2022, David Laight wrote: > > The PCI configuration space was retrofitted into x86 systems (and is > > accessed in an awkward manner with them), but with a new design such a > > clean approach is most welcome IMHO. Thank you for your explanation. > > Actually I think x86 was the initial system for PCI. > The PCI config space 'mess' is all about trying to make > something that wouldn't break existing memory maps. It was retrofitted in that x86 systems already existed for ~15 years when PCI came into picture. Therefore the makers of the CPU ISA couldn't have envisaged the need for config access instructions like they did for memory and port access. Maciej 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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 996A3C433EF for ; Fri, 6 May 2022 13:15:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:Message-ID: In-Reply-To:Subject:cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Ffa6YHe1dwn+kg3D1EV8tmq1vwecrhdGb2U0t34xnNc=; b=3brlGrZmQiFwbn EM8rY8d0UZNpL3Q3RtY107XOKpTnJ1Q4MP7LUBz6lYQYTnNeFrLW990mO2/McRV0jEWS2E/PpjM/E jZaQozDlSYiDSNz2D2Wotd1YZmi6naf0T2oqR9HIhS+bJZ2QDcFwVuCCMK8MfVQPTlkVBLgz14DLS mhJLQ+M8wxLRaKVzROu/0r5lhXc9yZVbFqm+dV75BxnfoQrprrkFXQ5RmJu0lwPfSv7JbV6RGUH8+ yX7eyfxgIQJNX2goUIfHRl2vXbMo4JE580vN6rtZB2NAgjHhHAkCs6QV+IpK147Vs46gKTRJx8IPL PjMxzVoR0SOcKb13shjg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nmxnf-003MoC-5o; Fri, 06 May 2022 13:15:15 +0000 Received: from angie.orcam.me.uk ([2001:4190:8020::34]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nmxnT-003MkJ-5e; Fri, 06 May 2022 13:15:05 +0000 Received: by angie.orcam.me.uk (Postfix, from userid 500) id F116B9200B4; Fri, 6 May 2022 15:15:00 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by angie.orcam.me.uk (Postfix) with ESMTP id ED3C892009E; Fri, 6 May 2022 14:15:00 +0100 (BST) Date: Fri, 6 May 2022 14:15:00 +0100 (BST) From: "Maciej W. Rozycki" To: David Laight cc: Arnd Bergmann , Rich Felker , "open list:IA64 (Itanium) PLATFORM" , "open list:SUPERH" , Catalin Marinas , Dave Hansen , "open list:MIPS" , "James E.J. Bottomley" , "open list:SPARC + UltraSPARC (sparc/sparc64)" , "open list:RISC-V ARCHITECTURE" , Will Deacon , linux-arch , Yoshinori Sato , Helge Deller , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Russell King , Ingo Molnar , Geert Uytterhoeven , linux-pci , Bjorn Helgaas , Matt Turner , Albert Ou , Arnd Bergmann , Niklas Schnelle , "open list:M68K ARCHITECTURE" , Ivan Kokshaysky , Paul Walmsley , Thomas Gleixner , "moderated list:ARM PORT" , Richard Henderson , Michal Simek , Thomas Bogendoerfer , "open list:PARISC ARCHITECTURE" , Greg Kroah-Hartman , Linux Kernel Mailing List , Palmer Dabbelt , "open list:ALPHA PORT" , Borislav Petkov , "open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)" , "David S. Miller" Subject: RE: [RFC v2 01/39] Kconfig: introduce HAS_IOPORT option and select it as necessary In-Reply-To: <5239892986c94239a122ab2f7a18a7a5@AcuMS.aculab.com> Message-ID: References: <20220505161028.GA492600@bhelgaas> <5239892986c94239a122ab2f7a18a7a5@AcuMS.aculab.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220506_061503_424120_9668966D X-CRM114-Status: GOOD ( 11.89 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Fri, 6 May 2022, David Laight wrote: > > The PCI configuration space was retrofitted into x86 systems (and is > > accessed in an awkward manner with them), but with a new design such a > > clean approach is most welcome IMHO. Thank you for your explanation. > > Actually I think x86 was the initial system for PCI. > The PCI config space 'mess' is all about trying to make > something that wouldn't break existing memory maps. It was retrofitted in that x86 systems already existed for ~15 years when PCI came into picture. Therefore the makers of the CPU ISA couldn't have envisaged the need for config access instructions like they did for memory and port access. Maciej _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv 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 Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 36B34C433EF for ; Fri, 6 May 2022 13:15:29 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4Kvrf75W49z3brH for ; Fri, 6 May 2022 23:15:27 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=orcam.me.uk (client-ip=78.133.224.34; helo=angie.orcam.me.uk; envelope-from=macro@orcam.me.uk; receiver=) Received: from angie.orcam.me.uk (angie.orcam.me.uk [78.133.224.34]) by lists.ozlabs.org (Postfix) with ESMTP id 4Kvrdh3RHsz3bXg for ; Fri, 6 May 2022 23:15:03 +1000 (AEST) Received: by angie.orcam.me.uk (Postfix, from userid 500) id F116B9200B4; Fri, 6 May 2022 15:15:00 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by angie.orcam.me.uk (Postfix) with ESMTP id ED3C892009E; Fri, 6 May 2022 14:15:00 +0100 (BST) Date: Fri, 6 May 2022 14:15:00 +0100 (BST) From: "Maciej W. Rozycki" To: David Laight Subject: RE: [RFC v2 01/39] Kconfig: introduce HAS_IOPORT option and select it as necessary In-Reply-To: <5239892986c94239a122ab2f7a18a7a5@AcuMS.aculab.com> Message-ID: References: <20220505161028.GA492600@bhelgaas> <5239892986c94239a122ab2f7a18a7a5@AcuMS.aculab.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Rich Felker , "open list:IA64 \(Itanium\) PLATFORM" , "open list:SUPERH" , Catalin Marinas , Dave Hansen , Linux Kernel Mailing List , "James E.J. Bottomley" , "open list:SPARC + UltraSPARC \(sparc/sparc64\)" , "open list:RISC-V ARCHITECTURE" , Will Deacon , linux-arch , Yoshinori Sato , Helge Deller , "maintainer:X86 ARCHITECTURE \(32-BIT AND 64-BIT\)" , Russell King , Ingo Molnar , Geert Uytterhoeven , linux-pci , Bjorn Helgaas , Matt Turner , Albert Ou , Arnd Bergmann , Niklas Schnelle , "open list:M68K ARCHITECTURE" , Ivan Kokshaysky , Paul Walmsley , Thomas Gleixner , "moderated list:ARM PORT" , Richard Henderson , Arnd Bergmann , Michal Simek , Thomas Bogendoerfer , "open list:PARISC ARCHITECTURE" , Greg Kroah-Hartman , "open list:MIPS" , Palmer Dabbelt , "open list:ALPHA PORT" , Borislav Petkov , "open list:LINUX FOR POWERPC \(32-BIT AND 64-BIT\)" , "David S. Miller" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Fri, 6 May 2022, David Laight wrote: > > The PCI configuration space was retrofitted into x86 systems (and is > > accessed in an awkward manner with them), but with a new design such a > > clean approach is most welcome IMHO. Thank you for your explanation. > > Actually I think x86 was the initial system for PCI. > The PCI config space 'mess' is all about trying to make > something that wouldn't break existing memory maps. It was retrofitted in that x86 systems already existed for ~15 years when PCI came into picture. Therefore the makers of the CPU ISA couldn't have envisaged the need for config access instructions like they did for memory and port access. Maciej 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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C28C2C433FE for ; Fri, 6 May 2022 13:16:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:Message-ID: In-Reply-To:Subject:cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Xzbz/HvGR69DjFvn4rUPfC80Ns56NQpNQeh+DsT9Qqk=; b=QVkjoMoLK/OXYe izv+2dUu/hr5YU9jj7kHwPpPYdqEILdUDHGTgOWBDIXV/6n8LSPIDsI+/MYbdZa/Z5g98cNAN7jhO M/KqL0CpvVzRPSxlIrnFOgR3WC3DogQBfaA0PZASdlKgCOLaZ2UId/+q57lb74znzJKiRs4q9FSWO nPrtQEG7PnXemCdIb3WKHlheZsKyRphlHZiAdTHclAF14kTxfVxkkKe+HxMfTHrnCquKiAx5MMtcm CF2OkguB3w1bqoPJIBtLycch9PIhXTugVlwgHX8uCEjG3hO+vrWX4jG5Rhy3mubcMOL3aIfNZIKuM EmkkcJlein71qWwTZDGg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nmxnW-003Mlf-PJ; Fri, 06 May 2022 13:15:06 +0000 Received: from angie.orcam.me.uk ([2001:4190:8020::34]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nmxnT-003MkJ-5e; Fri, 06 May 2022 13:15:05 +0000 Received: by angie.orcam.me.uk (Postfix, from userid 500) id F116B9200B4; Fri, 6 May 2022 15:15:00 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by angie.orcam.me.uk (Postfix) with ESMTP id ED3C892009E; Fri, 6 May 2022 14:15:00 +0100 (BST) Date: Fri, 6 May 2022 14:15:00 +0100 (BST) From: "Maciej W. Rozycki" To: David Laight cc: Arnd Bergmann , Rich Felker , "open list:IA64 (Itanium) PLATFORM" , "open list:SUPERH" , Catalin Marinas , Dave Hansen , "open list:MIPS" , "James E.J. Bottomley" , "open list:SPARC + UltraSPARC (sparc/sparc64)" , "open list:RISC-V ARCHITECTURE" , Will Deacon , linux-arch , Yoshinori Sato , Helge Deller , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Russell King , Ingo Molnar , Geert Uytterhoeven , linux-pci , Bjorn Helgaas , Matt Turner , Albert Ou , Arnd Bergmann , Niklas Schnelle , "open list:M68K ARCHITECTURE" , Ivan Kokshaysky , Paul Walmsley , Thomas Gleixner , "moderated list:ARM PORT" , Richard Henderson , Michal Simek , Thomas Bogendoerfer , "open list:PARISC ARCHITECTURE" , Greg Kroah-Hartman , Linux Kernel Mailing List , Palmer Dabbelt , "open list:ALPHA PORT" , Borislav Petkov , "open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)" , "David S. Miller" Subject: RE: [RFC v2 01/39] Kconfig: introduce HAS_IOPORT option and select it as necessary In-Reply-To: <5239892986c94239a122ab2f7a18a7a5@AcuMS.aculab.com> Message-ID: References: <20220505161028.GA492600@bhelgaas> <5239892986c94239a122ab2f7a18a7a5@AcuMS.aculab.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220506_061503_424120_9668966D X-CRM114-Status: GOOD ( 11.89 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, 6 May 2022, David Laight wrote: > > The PCI configuration space was retrofitted into x86 systems (and is > > accessed in an awkward manner with them), but with a new design such a > > clean approach is most welcome IMHO. Thank you for your explanation. > > Actually I think x86 was the initial system for PCI. > The PCI config space 'mess' is all about trying to make > something that wouldn't break existing memory maps. It was retrofitted in that x86 systems already existed for ~15 years when PCI came into picture. Therefore the makers of the CPU ISA couldn't have envisaged the need for config access instructions like they did for memory and port access. Maciej _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Maciej W. Rozycki" Date: Fri, 06 May 2022 13:15:00 +0000 Subject: RE: [RFC v2 01/39] Kconfig: introduce HAS_IOPORT option and select it as necessary Message-Id: List-Id: References: <20220505161028.GA492600@bhelgaas> <5239892986c94239a122ab2f7a18a7a5@AcuMS.aculab.com> In-Reply-To: <5239892986c94239a122ab2f7a18a7a5@AcuMS.aculab.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: David Laight Cc: Arnd Bergmann , Rich Felker , "open list:IA64 (Itanium) PLATFORM" , "open list:SUPERH" , Catalin Marinas , Dave Hansen , "open list:MIPS" , "James E.J. Bottomley" , "open list:SPARC + UltraSPARC (sparc/sparc64)" , "open list:RISC-V ARCHITECTURE" , Will Deacon , linux-arch , Yoshinori Sato , Helge Deller , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Russell King , Ingo Molnar , Geert Uytterhoeven , linux-pci , Bjorn Helgaas , Matt Turner , Albert Ou , Arnd Bergmann , Niklas Schnelle , "open list:M68K ARCHITECTURE" , Ivan Kokshaysky , Paul Walmsley , Thomas Gleixner , "moderated list:ARM PORT" , Richard Henderson , Michal Simek , Thomas Bogendoerfer , "open list:PARISC ARCHITECTURE" , Greg Kroah-Hartman , Linux Kernel Mailing List , Palmer Dabbelt , "open list:ALPHA PORT" , Borislav Petkov , "open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)" , "David S. Miller" On Fri, 6 May 2022, David Laight wrote: > > The PCI configuration space was retrofitted into x86 systems (and is > > accessed in an awkward manner with them), but with a new design such a > > clean approach is most welcome IMHO. Thank you for your explanation. > > Actually I think x86 was the initial system for PCI. > The PCI config space 'mess' is all about trying to make > something that wouldn't break existing memory maps. It was retrofitted in that x86 systems already existed for ~15 years when PCI came into picture. Therefore the makers of the CPU ISA couldn't have envisaged the need for config access instructions like they did for memory and port access. Maciej From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Maciej W. Rozycki" Subject: RE: [RFC v2 01/39] Kconfig: introduce HAS_IOPORT option and select it as necessary Date: Fri, 6 May 2022 14:15:00 +0100 (BST) Message-ID: References: <20220505161028.GA492600@bhelgaas> <5239892986c94239a122ab2f7a18a7a5@AcuMS.aculab.com> Mime-Version: 1.0 Return-path: In-Reply-To: <5239892986c94239a122ab2f7a18a7a5@AcuMS.aculab.com> List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: David Laight Cc: Arnd Bergmann , Rich Felker , "open list:IA64 (Itanium) PLATFORM" , "open list:SUPERH" , Catalin Marinas , Dave Hansen , "open list:MIPS" , "James E.J. Bottomley" , "open list:SPARC + UltraSPARC (sparc/sparc64)" , "open list:RISC-V ARCHITECTURE" , Will Deacon , linux-arch , Yoshinori Sato , Helge Deller , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Russell King On Fri, 6 May 2022, David Laight wrote: > > The PCI configuration space was retrofitted into x86 systems (and is > > accessed in an awkward manner with them), but with a new design such a > > clean approach is most welcome IMHO. Thank you for your explanation. > > Actually I think x86 was the initial system for PCI. > The PCI config space 'mess' is all about trying to make > something that wouldn't break existing memory maps. It was retrofitted in that x86 systems already existed for ~15 years when PCI came into picture. Therefore the makers of the CPU ISA couldn't have envisaged the need for config access instructions like they did for memory and port access. Maciej