From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [RFC v2] ARM VM System Specification Date: Wed, 11 Jun 2014 11:06:45 +0200 Message-ID: <9801429.iblEns5zC3@wuerfel> References: <20140328184517.GA27219@cbox> <20140611065412.GA24286@lvm> <53981043.3010300@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: Paolo Bonzini , Christoffer Dall , Peter Maydell , Ian Campbell , kvm-devel , Michael Casadevall , "marc.zyngier@arm.com" , Rob Herring , "cross-distro@lists.linaro.org" , "xen-devel@lists.xen.org" , Stefano Stabellini , Christopher Covington , Grant Likely , "kvmarm@lists.cs.columbia.edu" To: linux-arm-kernel@lists.infradead.org Return-path: Received: from mout.kundenserver.de ([212.227.126.187]:63358 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932410AbaFKJHY (ORCPT ); Wed, 11 Jun 2014 05:07:24 -0400 In-Reply-To: <53981043.3010300@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Wednesday 11 June 2014 10:16:03 Paolo Bonzini wrote: > > > If kernels actually do use the UEFI runtime services and have no need > > for direct access to an RTC when runing in a UEFI compliant system, then > > I agree with not specifying the hardware details. > > The RTC is not needed for ordinary operation of the kernel and, in the > current kernel, the EFI RTC driver is only used for IA64. However, it > seems to be platform independent. I'll give it a shot (on x86, since > that's the only architecture for which I know how to get UEFI firmware). Using the EFI RTC seems appropriate for ARM, as it's a reasonable abstraction that should work with any hypervisor. I suspect the only reason we don't use it on x86 is that we know which RTC hardware we have and the kernel comes with a mandatory driver already. Arnd