Re: [Xen-devel] [RFC v2] ARM VM System Specification

[Christoffer Dall <christoffer.dall@xxxxxxxxxx>]

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

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