From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Tue, 17 Jun 2014 15:46:15 +0100 From: Matthew Garrett To: "Rafael J. Wysocki" Cc: lenb@kernel.org, robert.moore@intel.com, lv.zheng@intel.com, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, bhelgaas@google.com Subject: Re: [PATCH 1/4] ACPI: Support _OSI("Darwin") correctly Message-ID: <20140617144614.GA16934@srcf.ucam.org> References: <1401640436-1947-1-git-send-email-matthew.garrett@nebula.com> <1401640436-1947-2-git-send-email-matthew.garrett@nebula.com> <7712179.sDPAd6Ubry@vostro.rjw.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <7712179.sDPAd6Ubry@vostro.rjw.lan> Sender: linux-acpi-owner@vger.kernel.org List-ID: On Tue, Jun 17, 2014 at 02:11:36PM +0200, Rafael J. Wysocki wrote: > On Sunday, June 01, 2014 12:33:53 PM Matthew Garrett wrote: > > Apple hardware queries _OSI("Darwin") in order to determine whether the > > system is running OS X, and changes firmware behaviour based on the answer. > > The most obvious difference in behaviour is that Thunderbolt hardware is > > forcibly powered down unless the system is running OS X. The obvious solution > > would be to simply add Darwin to the list of supported _OSI strings, but this > > causes problems. > > > > Recent Apple hardware includes two separate methods for checking _OSI > > strings. The first will check whether Darwin is supported, and if so will > > exit. The second will check whether Darwin is supported, but will then > > continue to check for further operating systems. If a further operating > > system is found then later firmware code will assume that the OS is not OS X. > > This results in the unfortunate situation where the Thunderbolt controller is > > available at boot time but remains powered down after suspend. > > > > The easiest way to handle this is to special-case it in the Linux-specific > > OSI handling code. If we see Darwin, we should answer true and then disable > > all other _OSI vendor strings. > > > > Signed-off-by: Matthew Garrett > > Does applying this patch without the rest of the series makes things worse > or better on the machines in question (or perhaps it doesn't matter at all > alone)? On its own, I think this will do nothing. -- Matthew Garrett | mjg59@srcf.ucam.org