Re: [PATCH] x86: Don't honour ACPI indicating absence of CMOS RTC

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Tue, Jun 17, 2014 at 05:01:12PM +0100, Jan Beulich wrote:
> >>> On 17.06.14 at 17:47, <konrad.wilk@oracle.com> wrote:
> > On Tue, Jun 17, 2014 at 04:12:32PM +0100, Jan Beulich wrote:
> >> >>> On 17.06.14 at 16:58, <andrew.cooper3@citrix.com> wrote:
> >> > This reverts f74556693 "x86: honor ACPI indicating absence of CMOS RTC"
> >> > 
> >> > Certain HP Gen8 BIOSes have started setting this bit despite an RTC CMOS 
> >> > being present and working.
> >> > 
> >> > Their reasonsing is to prevent EFI-booted OSes from playing with the CMOS,
> >> > combined with the erroneous assumption that the only OSes using legacy boot
> >> > are too old to know about ACPI v5 and therefore to understand this bit.
> >> 
> >> Which implies you can boot from EFI on those systems, which is
> >> precisely what the panic message says you ought to do. Why do
> >> you not boot via EFI in the first place?
> > 
> > You can swap between legacy and EFI in the BIOS. Customers can choose
> > either option.
> 
> I know on many systems you still can, but the question is "Why would
> you?" In particular when you know the firmware is assuming that the
> CSM is only being used by old OSes.

PCIe devices that don't EFI for setting up.
> 
> Jan
>