From mboxrd@z Thu Jan 1 00:00:00 1970 From: Geert Uytterhoeven Subject: Re: [PATCH] arch/tile: new multi-core architecture for Linux Date: Thu, 27 May 2010 15:41:44 +0200 Message-ID: References: <201005200543.o4K5hFRF006079@farm-0002.internal.tilera.com> <201005252345.15685.arnd@arndb.de> <4BFDC3D1.40708@tilera.com> <201005271041.30519.arnd@arndb.de> <4BFE73DF.5090107@tilera.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail-pw0-f46.google.com ([209.85.160.46]:50203 "EHLO mail-pw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754247Ab0E0Nlp convert rfc822-to-8bit (ORCPT ); Thu, 27 May 2010 09:41:45 -0400 In-Reply-To: <4BFE73DF.5090107@tilera.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Chris Metcalf Cc: Arnd Bergmann , Linux Kernel Mailing List , Linus Torvalds , linux-arch@vger.kernel.org On Thu, May 27, 2010 at 15:30, Chris Metcalf wrot= e: > On 5/27/2010 4:41 AM, Arnd Bergmann wrote: >> On Thursday 27 May 2010, Chris Metcalf wrote: >>>> +EXPORT_SYMBOL(inb); >>>> >>>> If you just remove these definitions, you get a link error for any >>>> driver that tries to use these, which is probably more helpful tha= n >>>> the panic. >>>> >>>> OTOH, are you sure that you can't just map the PIO calls to mmio f= unctions >>>> like readb plus some fixed offset? On most non-x86 architectures, = the PIO >>>> area of the PCI bus is just mapped to a memory range somewhere. >>>> >>>> >>> I'll try to remove them and see if anything falls over. =C2=A0We do= n't have >>> any memory-mapped addresses in the 32-bit architecture, though that >>> changes with the 64-bit architecture, which introduces IO mappings.= =C2=A0For >>> PCI we actually have to do a hypervisor transaction for reads or wr= ites. >>> >> Ok, then I assume that PIO would also be a hypervisor call, right? >> If you don't have MMIO on 32 bit, you might want to not define eithe= r >> PIO (inb, ...) no MMIO (readb, ...) calls there and disable >> CONFIG_HAVE_MMIO in Kconfig. >> > > We don't define CONFIG_HAVE_MMIO, but drivers certainly seem to use > ioread/iowrite methods as well as inb/outb without guarding them with > any particular tests, so we have to provide definitions of some kind = for > all of them. =C2=A0I'll confer with our PCI developer to see if we ca= n clean > up the set of definitions in io.h. It's CONFIG_NO_IOMEM (cfr. s390 and um), which is inverted and turned i= nto CONFIG_HAS_IOMEM, to be checked by drivers. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-= m68k.org In personal conversations with technical people, I call myself a hacker= =2E But when I'm talking to journalists I just say "programmer" or something li= ke that. -- Linus Torvalds