Re: [PATCH] x86/efi-bgrt: Switch pr_err() to pr_debug() for invalid BGRT

[josh@joshtriplett.org]

On Mon, Jun 29, 2015 at 05:44:58PM +0200, Borislav Petkov wrote:
> On Mon, Jun 29, 2015 at 03:49:40PM +0100, Matt Fleming wrote:
> > It still makes sense to have the error message because the kernel
> > literally does not know what the firmware is trying to achieve by
> > setting those bits.
> > 
> > But I agree with Josh that for the specific case of "reserved bits",
> > FW_BUG is wrong, because if in some future version of the spec those
> > bits get used, seeing,
> > 
> >   "[Firmware Bug]: Ignoring BGRT: reserved bits are non-zero 0x3"
> 
> I still don't see what that message brings if some kernel complains that
> some bits are !0 then. Are they valid bits which the kernel doesn't know
> about or are they erroneously set and reserved. This, IMHO, is confusing
> because the error message is not correct in all cases.
> 
> Thus my suggestion to either check the spec version before looking at
> the bits or find out in some other way which bits are defined and which
> are reserved and warn only about the reserved ones which are 1b.

The version is already checked *before* the status bits: if the version
is not 1, the kernel stops there and ignores the BGRT, before printing a
message about status.

- Josh Triplett