Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 12 Nov 2001 02:33:02 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 12 Nov 2001 02:32:42 -0500 Received: from main.sonytel.be ([195.0.45.167]:41083 "EHLO mail.sonytel.be") by vger.kernel.org with ESMTP id ; Mon, 12 Nov 2001 02:32:39 -0500 Date: Mon, 12 Nov 2001 08:31:47 +0100 (MET) From: Geert Uytterhoeven To: James Simmons cc: Bakonyi Ferenc , Linux Kernel Development Subject: Re: isa_* problems (hgafb is broken since 2.4.13) In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 8 Nov 2001, James Simmons wrote: > > I have two questions about asm-i386/io.h: > > 1. Why #define __ISA_IO_base ((char *)(PAGE_OFFSET)) ? > > 2. Why not #define __ISA_IO_base ((char *)0) ? > > For ix86 the ISA IO space start is at the very begining of memory. On > other platforms like the PPC the ISA IO space is seperate from the > regular memory space. It starts after the regular memory space thus the > __ISA_IO_base will not be 0x0. He's talking about asm-i386/io.h. __ISA_IO_base (what's in a name, why not call it __ISA_MEM_base?!?!?) is the kernel virtual address of the start of ISA _memory_ space. On ia32 PCs, ISA memory space overlaps with the first 16 MB of real RAM, at CPU physical address 0. (DISCLAIMER: my ia32 knowledge is limited) 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. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/