From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752648AbbBJUmu (ORCPT ); Tue, 10 Feb 2015 15:42:50 -0500 Received: from g4t3425.houston.hp.com ([15.201.208.53]:33568 "EHLO g4t3425.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751941AbbBJUms (ORCPT ); Tue, 10 Feb 2015 15:42:48 -0500 Message-ID: <1423600952.1128.9.camel@misato.fc.hp.com> Subject: Re: [PATCH v2 5/7] x86, mm: Support huge KVA mappings on x86 From: Toshi Kani To: Dave Hansen 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 Date: Tue, 10 Feb 2015 13:42:32 -0700 In-Reply-To: <54DA54FA.7010707@intel.com> References: <1423521935-17454-1-git-send-email-toshi.kani@hp.com> <1423521935-17454-6-git-send-email-toshi.kani@hp.com> <54DA54FA.7010707@intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4 (3.10.4-4.fc20) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2015-02-10 at 10:59 -0800, Dave Hansen wrote: > On 02/09/2015 02:45 PM, Toshi Kani wrote: > > Implement huge KVA mapping interfaces on x86. Select > > HAVE_ARCH_HUGE_VMAP when X86_64 or X86_32 with X86_PAE is set. > > Without X86_PAE set, the X86_32 kernel has the 2-level page > > tables and cannot provide the huge KVA mappings. > > Not that it's a big deal, but what's the limitation with the 2-level > page tables on 32-bit? We have a 4MB large page size available there > and we already use it for the kernel linear mapping. ioremap() calls arch-neutral ioremap_page_range() to set up I/O mappings with PTEs. This patch-set enables ioremap_page_range() to set up PUD & PMD mappings. With 2-level page table, I do not think this PUD/PMD mapping code works unless we add some special code. Thanks, -Toshi