From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753261AbbBPQcx (ORCPT ); Mon, 16 Feb 2015 11:32:53 -0500 Received: from foss-mx-na.arm.com ([217.140.108.86]:43823 "EHLO foss-mx-na.foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752636AbbBPQcw (ORCPT ); Mon, 16 Feb 2015 11:32:52 -0500 Date: Mon, 16 Feb 2015 16:32:48 +0000 From: Will Deacon To: Chris Clayton Cc: LKML Subject: Re: [PATCH] iommu: prompt for IOMMU_IO_PGTABLE_LPAE on ARM archs only Message-ID: <20150216163247.GM10634@arm.com> References: <54E0803F.5080707@googlemail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <54E0803F.5080707@googlemail.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Chris, On Sun, Feb 15, 2015 at 11:17:19AM +0000, Chris Clayton wrote: > When running "make oldconfig" for an x86_64 kernel, I was prompted for a > setting for IOMMU_IO_PGTABLE_LPAE. From the prompt and the help text it > appears that this config item is relevant to ARMv7/v8 only. This patch > prevents the prompt on non-ARM architectures. Compile tested building a > cross-compiled x86_64 kernel in an x86 user space. The resultant kernel > boots fine and I am running it now. > > Fixes: e1d3c0fd701df831169b116cd5c5d6203ac07f70 > Cc: will.deacon@arm.com > Signed-off-by: Chris Clayton > > --- linux/drivers/iommu/Kconfig.orig 2015-02-15 09:44:01.235927248 +0000 > +++ linux/drivers/iommu/Kconfig 2015-02-15 09:44:41.131926434 +0000 > @@ -22,6 +22,7 @@ config IOMMU_IO_PGTABLE > > config IOMMU_IO_PGTABLE_LPAE > bool "ARMv7/v8 Long Descriptor Format" > + depends on ARM || ARM64 > select IOMMU_IO_PGTABLE > help > Enable support for the ARM long descriptor pagetable format. What's the problem with this? The page-table code is intentionally decoupled from the CPU architecture and having this boot-tested on x86 found some real bugs that I'm currently fixing. Sure, you probably don't need this on your box, but it's not default y and you don't have to select it. Will