From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB1ECC433FF for ; Mon, 5 Aug 2019 13:26:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A11A820651 for ; Mon, 5 Aug 2019 13:26:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565011580; bh=mgBiOlhHTK7qh+vZs/EDlJVRM6VssQoHvpI2drPK8Os=; h=Subject:To:Cc:References:From:Date:In-Reply-To:List-ID:From; b=qINO3VDdrkoe947Hnk/2kbBsFLmweGuc7CcvzdTFsO1ouiJthlBB7lh1Xl5OmUUfs NG9pc+Bu/VY6VdiH1kycwoitg5JhcAIy5hQ/lrSLpsJkmqPHn4ZNr46GjMhYNLZzoI 4Li4MRDiBwWiRD5RDssDxIECpI4tDMa7gs/C1nD0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731418AbfHEN0P (ORCPT ); Mon, 5 Aug 2019 09:26:15 -0400 Received: from foss.arm.com ([217.140.110.172]:48942 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731391AbfHEN0L (ORCPT ); Mon, 5 Aug 2019 09:26:11 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4AE44337; Mon, 5 Aug 2019 06:26:10 -0700 (PDT) Received: from [10.1.197.61] (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 97F263F706; Mon, 5 Aug 2019 06:26:08 -0700 (PDT) Subject: Re: [PATCH 0/9] arm64: Stolen time support To: Steven Price Cc: kvm@vger.kernel.org, =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Catalin Marinas , Suzuki K Pouloze , linux-doc@vger.kernel.org, Russell King , linux-kernel@vger.kernel.org, James Morse , linux-arm-kernel@lists.infradead.org, Paolo Bonzini , Will Deacon , kvmarm@lists.cs.columbia.edu, Julien Thierry References: <20190802145017.42543-1-steven.price@arm.com> <20190803190522.5fec8f7d@why> <6789f477-8ab5-cc54-1ad2-8627917b07c9@arm.com> From: Marc Zyngier Organization: Approximate Message-ID: Date: Mon, 5 Aug 2019 14:26:07 +0100 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <6789f477-8ab5-cc54-1ad2-8627917b07c9@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/08/2019 14:06, Steven Price wrote: > On 03/08/2019 19:05, Marc Zyngier wrote: >> On Fri, 2 Aug 2019 15:50:08 +0100 >> Steven Price wrote: >> >> Hi Steven, >> >>> This series add support for paravirtualized time for arm64 guests and >>> KVM hosts following the specification in Arm's document DEN 0057A: >>> >>> https://developer.arm.com/docs/den0057/a >>> >>> It implements support for stolen time, allowing the guest to >>> identify time when it is forcibly not executing. >>> >>> It doesn't implement support for Live Physical Time (LPT) as there are >>> some concerns about the overheads and approach in the above >>> specification, and I expect an updated version of the specification to >>> be released soon with just the stolen time parts. >> >> Thanks for posting this. >> >> My current concern with this series is around the fact that we allocate >> memory from the kernel on behalf of the guest. It is the first example >> of such thing in the ARM port, and I can't really say I'm fond of it. >> >> x86 seems to get away with it by having the memory allocated from >> userspace, why I tend to like more. Yes, put_user is more >> expensive than a straight store, but this isn't done too often either. >> >> What is the rational for your current approach? > > As I see it there are 3 approaches that can be taken here: > > 1. Hypervisor allocates memory and adds it to the virtual machine. This > means that everything to do with the 'device' is encapsulated behind the > KVM_CREATE_DEVICE / KVM_[GS]ET_DEVICE_ATTR ioctls. But since we want the > stolen time structure to be fast it cannot be a trapping region and has > to be backed by real memory - in this case allocated by the host kernel. > > 2. Host user space allocates memory. Similar to above, but this time > user space needs to manage the memory region as well as the usual > KVM_CREATE_DEVICE dance. I've no objection to this, but it means > kvmtool/QEMU needs to be much more aware of what is going on (e.g. how > to size the memory region). > > 3. Guest kernel "donates" the memory to the hypervisor for the > structure. As far as I'm aware this is what x86 does. The problems I see > this approach are: > > a) kexec becomes much more tricky - there needs to be a disabling > mechanism for the guest to stop the hypervisor scribbling on memory > before starting the new kernel. > > b) If there is more than one entity that is interested in the > information (e.g. firmware and kernel) then this requires some form of > arbitration in the guest because the hypervisor doesn't want to have to > track an arbitrary number of regions to update. > > c) Performance can suffer if the host kernel doesn't have a suitably > aligned/sized area to use. As you say - put_user() is more expensive. > The structure is updated on every return to the VM. > > > Of course x86 does prove the third approach can work, but I'm not sure > which is actually better. Avoid the kexec cancellation requirements was > the main driver of the current approach. Although many of the > conversations about this were also tied up with Live Physical Time which > adds its own complications. My current train of thoughts is around (2): - We don't need a new mechanism to track pages or deal with overlapping IPA ranges - We can get rid of the save/restore interface The drawback is that the amount of memory required per vcpu becomes ABI. I don't think that's a huge deal, as the hypervisor has the same contract with the guest. We also take a small hit with put_user(), but this is only done as a consequence of vcpu_load() (and not on every entry as you suggest above). It'd be worth quantifying this overhead before making any decision one way or another. Thanks, M. -- Jazz is not dead, it just smells funny... From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6FD28C0650F for ; Mon, 5 Aug 2019 13:26:16 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 0722F20657 for ; Mon, 5 Aug 2019 13:26:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0722F20657 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 63C294A546; Mon, 5 Aug 2019 09:26:15 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id bjhPHgt2vIrf; Mon, 5 Aug 2019 09:26:14 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 122234A51F; Mon, 5 Aug 2019 09:26:14 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 49DB64A4FB for ; Mon, 5 Aug 2019 09:26:12 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id eJybgLvMREdT for ; Mon, 5 Aug 2019 09:26:11 -0400 (EDT) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by mm01.cs.columbia.edu (Postfix) with ESMTP id E12494A4BE for ; Mon, 5 Aug 2019 09:26:10 -0400 (EDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4AE44337; Mon, 5 Aug 2019 06:26:10 -0700 (PDT) Received: from [10.1.197.61] (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 97F263F706; Mon, 5 Aug 2019 06:26:08 -0700 (PDT) Subject: Re: [PATCH 0/9] arm64: Stolen time support To: Steven Price References: <20190802145017.42543-1-steven.price@arm.com> <20190803190522.5fec8f7d@why> <6789f477-8ab5-cc54-1ad2-8627917b07c9@arm.com> From: Marc Zyngier Organization: Approximate Message-ID: Date: Mon, 5 Aug 2019 14:26:07 +0100 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <6789f477-8ab5-cc54-1ad2-8627917b07c9@arm.com> Content-Language: en-US Cc: kvm@vger.kernel.org, Catalin Marinas , linux-doc@vger.kernel.org, Russell King , linux-kernel@vger.kernel.org, Paolo Bonzini , Will Deacon , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On 05/08/2019 14:06, Steven Price wrote: > On 03/08/2019 19:05, Marc Zyngier wrote: >> On Fri, 2 Aug 2019 15:50:08 +0100 >> Steven Price wrote: >> >> Hi Steven, >> >>> This series add support for paravirtualized time for arm64 guests and >>> KVM hosts following the specification in Arm's document DEN 0057A: >>> >>> https://developer.arm.com/docs/den0057/a >>> >>> It implements support for stolen time, allowing the guest to >>> identify time when it is forcibly not executing. >>> >>> It doesn't implement support for Live Physical Time (LPT) as there are >>> some concerns about the overheads and approach in the above >>> specification, and I expect an updated version of the specification to >>> be released soon with just the stolen time parts. >> >> Thanks for posting this. >> >> My current concern with this series is around the fact that we allocate >> memory from the kernel on behalf of the guest. It is the first example >> of such thing in the ARM port, and I can't really say I'm fond of it. >> >> x86 seems to get away with it by having the memory allocated from >> userspace, why I tend to like more. Yes, put_user is more >> expensive than a straight store, but this isn't done too often either. >> >> What is the rational for your current approach? > > As I see it there are 3 approaches that can be taken here: > > 1. Hypervisor allocates memory and adds it to the virtual machine. This > means that everything to do with the 'device' is encapsulated behind the > KVM_CREATE_DEVICE / KVM_[GS]ET_DEVICE_ATTR ioctls. But since we want the > stolen time structure to be fast it cannot be a trapping region and has > to be backed by real memory - in this case allocated by the host kernel. > > 2. Host user space allocates memory. Similar to above, but this time > user space needs to manage the memory region as well as the usual > KVM_CREATE_DEVICE dance. I've no objection to this, but it means > kvmtool/QEMU needs to be much more aware of what is going on (e.g. how > to size the memory region). > > 3. Guest kernel "donates" the memory to the hypervisor for the > structure. As far as I'm aware this is what x86 does. The problems I see > this approach are: > > a) kexec becomes much more tricky - there needs to be a disabling > mechanism for the guest to stop the hypervisor scribbling on memory > before starting the new kernel. > > b) If there is more than one entity that is interested in the > information (e.g. firmware and kernel) then this requires some form of > arbitration in the guest because the hypervisor doesn't want to have to > track an arbitrary number of regions to update. > > c) Performance can suffer if the host kernel doesn't have a suitably > aligned/sized area to use. As you say - put_user() is more expensive. > The structure is updated on every return to the VM. > > > Of course x86 does prove the third approach can work, but I'm not sure > which is actually better. Avoid the kexec cancellation requirements was > the main driver of the current approach. Although many of the > conversations about this were also tied up with Live Physical Time which > adds its own complications. My current train of thoughts is around (2): - We don't need a new mechanism to track pages or deal with overlapping IPA ranges - We can get rid of the save/restore interface The drawback is that the amount of memory required per vcpu becomes ABI. I don't think that's a huge deal, as the hypervisor has the same contract with the guest. We also take a small hit with put_user(), but this is only done as a consequence of vcpu_load() (and not on every entry as you suggest above). It'd be worth quantifying this overhead before making any decision one way or another. Thanks, M. -- Jazz is not dead, it just smells funny... _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 237D3C32751 for ; Mon, 5 Aug 2019 13:26:15 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id ECF1120657 for ; Mon, 5 Aug 2019 13:26:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="oKbEAEOX" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ECF1120657 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Rs8ZjZ+gx3TO4QeRBniUqlxDBFzlPT11xaJwLUJz0j4=; b=oKbEAEOXZ6U1j5 iQnTyd78fgOrvZ7M4q7R0vdeOWYuMNd3yfjOlvZG4DY9kxBb+9HRE/WM1+MOOzI01C80ucGP4uXWz 8CTXqiE/DTi4lBK0EJilr6VDITT+CpmXy1BWx9/mWMTw/t0SwH5fWA1az0EPHc4rsceKJ8nhCNWZ2 3ojTB9aNXDDP56HQGC+bZwilZJYbL14aaGW7c3+06u2uYq9e0ku1RsU7HIm17m83W3hewgmurE6NM IGBWu3+zSMwssh6WtlyaJ4RrIF1SCHvvk8eBQOPtVIL/6Ll5gHwy0mT1mIfAtWIcWHe3ttHCI/i8s YSQ3Vcwdb+jWZJmDeBpA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hud0A-0003Tp-CB; Mon, 05 Aug 2019 13:26:14 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hud07-0003TI-4H for linux-arm-kernel@lists.infradead.org; Mon, 05 Aug 2019 13:26:12 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4AE44337; Mon, 5 Aug 2019 06:26:10 -0700 (PDT) Received: from [10.1.197.61] (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 97F263F706; Mon, 5 Aug 2019 06:26:08 -0700 (PDT) Subject: Re: [PATCH 0/9] arm64: Stolen time support To: Steven Price References: <20190802145017.42543-1-steven.price@arm.com> <20190803190522.5fec8f7d@why> <6789f477-8ab5-cc54-1ad2-8627917b07c9@arm.com> From: Marc Zyngier Organization: Approximate Message-ID: Date: Mon, 5 Aug 2019 14:26:07 +0100 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <6789f477-8ab5-cc54-1ad2-8627917b07c9@arm.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190805_062611_286893_387C827E X-CRM114-Status: GOOD ( 25.72 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , kvm@vger.kernel.org, Suzuki K Pouloze , Catalin Marinas , linux-doc@vger.kernel.org, Russell King , linux-kernel@vger.kernel.org, James Morse , Julien Thierry , Paolo Bonzini , Will Deacon , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 05/08/2019 14:06, Steven Price wrote: > On 03/08/2019 19:05, Marc Zyngier wrote: >> On Fri, 2 Aug 2019 15:50:08 +0100 >> Steven Price wrote: >> >> Hi Steven, >> >>> This series add support for paravirtualized time for arm64 guests and >>> KVM hosts following the specification in Arm's document DEN 0057A: >>> >>> https://developer.arm.com/docs/den0057/a >>> >>> It implements support for stolen time, allowing the guest to >>> identify time when it is forcibly not executing. >>> >>> It doesn't implement support for Live Physical Time (LPT) as there are >>> some concerns about the overheads and approach in the above >>> specification, and I expect an updated version of the specification to >>> be released soon with just the stolen time parts. >> >> Thanks for posting this. >> >> My current concern with this series is around the fact that we allocate >> memory from the kernel on behalf of the guest. It is the first example >> of such thing in the ARM port, and I can't really say I'm fond of it. >> >> x86 seems to get away with it by having the memory allocated from >> userspace, why I tend to like more. Yes, put_user is more >> expensive than a straight store, but this isn't done too often either. >> >> What is the rational for your current approach? > > As I see it there are 3 approaches that can be taken here: > > 1. Hypervisor allocates memory and adds it to the virtual machine. This > means that everything to do with the 'device' is encapsulated behind the > KVM_CREATE_DEVICE / KVM_[GS]ET_DEVICE_ATTR ioctls. But since we want the > stolen time structure to be fast it cannot be a trapping region and has > to be backed by real memory - in this case allocated by the host kernel. > > 2. Host user space allocates memory. Similar to above, but this time > user space needs to manage the memory region as well as the usual > KVM_CREATE_DEVICE dance. I've no objection to this, but it means > kvmtool/QEMU needs to be much more aware of what is going on (e.g. how > to size the memory region). > > 3. Guest kernel "donates" the memory to the hypervisor for the > structure. As far as I'm aware this is what x86 does. The problems I see > this approach are: > > a) kexec becomes much more tricky - there needs to be a disabling > mechanism for the guest to stop the hypervisor scribbling on memory > before starting the new kernel. > > b) If there is more than one entity that is interested in the > information (e.g. firmware and kernel) then this requires some form of > arbitration in the guest because the hypervisor doesn't want to have to > track an arbitrary number of regions to update. > > c) Performance can suffer if the host kernel doesn't have a suitably > aligned/sized area to use. As you say - put_user() is more expensive. > The structure is updated on every return to the VM. > > > Of course x86 does prove the third approach can work, but I'm not sure > which is actually better. Avoid the kexec cancellation requirements was > the main driver of the current approach. Although many of the > conversations about this were also tied up with Live Physical Time which > adds its own complications. My current train of thoughts is around (2): - We don't need a new mechanism to track pages or deal with overlapping IPA ranges - We can get rid of the save/restore interface The drawback is that the amount of memory required per vcpu becomes ABI. I don't think that's a huge deal, as the hypervisor has the same contract with the guest. We also take a small hit with put_user(), but this is only done as a consequence of vcpu_load() (and not on every entry as you suggest above). It'd be worth quantifying this overhead before making any decision one way or another. Thanks, M. -- Jazz is not dead, it just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel