From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoffer Dall Subject: Re: [RFC v2] ARM VM System Specification Date: Mon, 30 Jun 2014 13:46:47 -0700 Message-ID: <20140630204647.GA19743@cbox> References: <20140328184517.GA27219@cbox> <20140611065412.GA24286@lvm> <53981043.3010300@redhat.com> <9801429.iblEns5zC3@wuerfel> <53B18E03.4050902@jonmasters.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Arnd Bergmann , linux-arm-kernel@lists.infradead.org, Paolo Bonzini , 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: Jon Masters Return-path: Received: from mail-lb0-f173.google.com ([209.85.217.173]:38603 "EHLO mail-lb0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750771AbaF3Uqo (ORCPT ); Mon, 30 Jun 2014 16:46:44 -0400 Received: by mail-lb0-f173.google.com with SMTP id s7so6340597lbd.32 for ; Mon, 30 Jun 2014 13:46:42 -0700 (PDT) Content-Disposition: inline In-Reply-To: <53B18E03.4050902@jonmasters.org> Sender: kvm-owner@vger.kernel.org List-ID: On Mon, Jun 30, 2014 at 12:19:15PM -0400, Jon Masters wrote: > On 6/11/14, 5:06 AM, Arnd Bergmann wrote: > >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. > > (sorry for delay in responding to this thread) > > Indeed. We should use the EFI RTC driver in general, rather than > push for many individual RTC drivers on aarch64 systems that are EFI > enabled. Within Red Hat, we currently have EFI Runtime Services live > in many of our labs and are using the EFI RTC. This is the way > forward. > Seems like we should stick a note in there about being UEFI compatible requires an RTC. We went this far before Peter raised the issue with noone else realizing it, so it seems like a good idea to me. -Christoffer From mboxrd@z Thu Jan 1 00:00:00 1970 From: christoffer.dall@linaro.org (Christoffer Dall) Date: Mon, 30 Jun 2014 13:46:47 -0700 Subject: [RFC v2] ARM VM System Specification In-Reply-To: <53B18E03.4050902@jonmasters.org> References: <20140328184517.GA27219@cbox> <20140611065412.GA24286@lvm> <53981043.3010300@redhat.com> <9801429.iblEns5zC3@wuerfel> <53B18E03.4050902@jonmasters.org> Message-ID: <20140630204647.GA19743@cbox> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Jun 30, 2014 at 12:19:15PM -0400, Jon Masters wrote: > On 6/11/14, 5:06 AM, Arnd Bergmann wrote: > >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. > > (sorry for delay in responding to this thread) > > Indeed. We should use the EFI RTC driver in general, rather than > push for many individual RTC drivers on aarch64 systems that are EFI > enabled. Within Red Hat, we currently have EFI Runtime Services live > in many of our labs and are using the EFI RTC. This is the way > forward. > Seems like we should stick a note in there about being UEFI compatible requires an RTC. We went this far before Peter raised the issue with noone else realizing it, so it seems like a good idea to me. -Christoffer