From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Fedin Subject: RE: [RFC] Handling CP15 timer without in-kernel irqchip Date: Fri, 02 Oct 2015 13:22:54 +0300 Message-ID: <00cd01d0fcfc$4de250e0$e9a6f2a0$@samsung.com> References: <00a001d0fce3$f76e2170$e64a6450$@samsung.com> <560E4EC4.5050101@redhat.com> <560E56DC.6020406@redhat.com> <560E59FA.9070205@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Cc: kvmarm@lists.cs.columbia.edu, 'kvm-devel' , 'Marc Zyngier' To: 'Paolo Bonzini' , 'Peter Maydell' Return-path: Received: from mailout2.w1.samsung.com ([210.118.77.12]:53444 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751425AbbJBKW6 convert rfc822-to-8bit (ORCPT ); Fri, 2 Oct 2015 06:22:58 -0400 Received: from eucpsbgm1.samsung.com (unknown [203.254.199.244]) by mailout2.w1.samsung.com (Oracle Communications Messaging Server 7.0.5.31.0 64bit (built May 5 2014)) with ESMTP id <0NVL00KFH8U8XF50@mailout2.w1.samsung.com> for kvm@vger.kernel.org; Fri, 02 Oct 2015 11:22:56 +0100 (BST) In-reply-to: <560E59FA.9070205@redhat.com> Content-language: ru Sender: kvm-owner@vger.kernel.org List-ID: Hello! > I mean in the device tree. Does the boot loader realize it's under a > hypervisor, and provide different device trees to the kernel? This has nothing to do with the device tree. Device tree is static. The logic sits inside Linux kernel itself: a) If we are running in HYP mode (we are host) - use physical timer b) If there's no virtual timer IRQ specified - use physical timer c) Otherwise - use virtual vimer. On systems without virtualization support virtual timer is simply aliased to physical timer, this is architectural requirement. Therefore this logic just works everywhere. Kind regards, Pavel Fedin Expert Engineer Samsung Electronics Research center Russia