Re: Please revert "ACPICA: AML interpreter: add region addresses in global list during initialization"

[Jean Delvare <jdelvare@suse.de>]

On Tue, 20 Nov 2018 09:54:19 +0100, Greg KH wrote:
> On Tue, Nov 20, 2018 at 09:46:49AM +0100, Jean Delvare wrote:
> > Dear stable kernel team,
> > 
> > In stable kernel 4.19.2, the following upstream commit was included:
> > 
> > commit 4abb951b73ff0a8a979113ef185651aa3c8da19b
> > Author: Erik Schmauss
> > Date:   Wed Oct 17 14:09:35 2018 -0700
> > 
> >     ACPICA: AML interpreter: add region addresses in global list during initialization
> >
> > (...)
> > Please revert this commit from future stable kernels on all affected
> > branches (I think only 4.18.19 and 4.19.2 are affected at the moment,
> > but maybe other affected releases are in the works already).  
> 
> Ok, I'll go revert this, but shouldn't it also be reverted in Linus's
> tree as well?

No. As I understand it (with my limited knowledge of ACPICA), the
change itself is correct. The problem is that it will detect resource
conflicts which were unnoticed before, and that will prevent drivers
from loading. Some of them may be addressed with driver fixes or new
drivers. Others are false positives (due to bogus BIOS) which users
will have to work around with acpi_resource_conflicts=lax. We have been
through this before, nothing new really, but it takes years to address
such problems. This just can't be done in stable kernel series.

Thanks,
-- 
Jean Delvare
SUSE L3 Support