Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262797AbTIVVyp (ORCPT ); Mon, 22 Sep 2003 17:54:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262799AbTIVVyp (ORCPT ); Mon, 22 Sep 2003 17:54:45 -0400 Received: from mail.jlokier.co.uk ([81.29.64.88]:43649 "EHLO mail.jlokier.co.uk") by vger.kernel.org with ESMTP id S262797AbTIVVyo (ORCPT ); Mon, 22 Sep 2003 17:54:44 -0400 Date: Mon, 22 Sep 2003 22:54:32 +0100 From: Jamie Lokier To: "Eric W. Biederman" Cc: linux@horizon.com, linux-kernel@vger.kernel.org Subject: Re: Can we kill f inb_p, outb_p and other random I/O on port 0x80, in 2.6? Message-ID: <20030922215432.GE29869@mail.jlokier.co.uk> References: <20030922153651.16497.qmail@science.horizon.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 868 Lines: 21 linux@horizon.com writes: > > So can we gradually kill inb_p, outb_p in 2.6? An the other > > miscellaneous users of I/O port 0x80 for I/O delays? > > Actually, It's not easy. The issue got debated a lot a few years ago. > A read is also acceptable, and allows a few more ports to be > potentially used, but that corrupts %al and thus bloats the code. It bloats the code a lot less than udelay() calls or any other solution which keeps the delay! In the worst case, the bloat from a read _should_ be two bytes: "push %eax; inb $80,%al; pop %eax". Whereas a call to udelay is 5 bytes, for a call instruction. -- Jamie - 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/