From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f182.google.com (mail-wi0-f182.google.com [209.85.212.182]) by kanga.kvack.org (Postfix) with ESMTP id 8E51E6B00A2 for ; Wed, 18 Feb 2015 15:44:20 -0500 (EST) Received: by mail-wi0-f182.google.com with SMTP id l15so4923771wiw.3 for ; Wed, 18 Feb 2015 12:44:20 -0800 (PST) Received: from mail-wi0-x22a.google.com (mail-wi0-x22a.google.com. [2a00:1450:400c:c05::22a]) by mx.google.com with ESMTPS id hh1si37111139wib.9.2015.02.18.12.44.18 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 18 Feb 2015 12:44:19 -0800 (PST) Received: by mail-wi0-f170.google.com with SMTP id hi2so41522526wib.1 for ; Wed, 18 Feb 2015 12:44:18 -0800 (PST) Date: Wed, 18 Feb 2015 21:44:14 +0100 From: Ingo Molnar Subject: Re: [PATCH v2 6/7] x86, mm: Support huge I/O mappings on x86 Message-ID: <20150218204414.GA20943@gmail.com> References: <1423521935-17454-1-git-send-email-toshi.kani@hp.com> <1423521935-17454-7-git-send-email-toshi.kani@hp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1423521935-17454-7-git-send-email-toshi.kani@hp.com> Sender: owner-linux-mm@kvack.org List-ID: To: Toshi Kani Cc: akpm@linux-foundation.org, hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, arnd@arndb.de, linux-mm@kvack.org, x86@kernel.org, linux-kernel@vger.kernel.org, Elliott@hp.com * Toshi Kani wrote: > This patch implements huge I/O mapping capability interfaces on x86. > +#ifdef CONFIG_HUGE_IOMAP > +#ifdef CONFIG_X86_64 > +#define IOREMAP_MAX_ORDER (PUD_SHIFT) > +#else > +#define IOREMAP_MAX_ORDER (PMD_SHIFT) > +#endif > +#endif /* CONFIG_HUGE_IOMAP */ > +#ifdef CONFIG_HUGE_IOMAP Hm, so why is there a Kconfig option for this? It just complicates things. For example the kernel already defaults to mapping itself with as large mappings as possible, without a Kconfig entry for it. There's no reason to make this configurable - and quite a bit of complexity in the patches comes from this configurability. Thanks, Ingo -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org