linux-kernel - Re: RTC_DRV_CMOS can break userspace interface

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Message-ID: <20070527233911.GA23491@srcf.ucam.org>
Date:	Mon, 28 May 2007 00:39:11 +0100
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org
Cc:	david-b@...bell.net
Subject: Re: RTC_DRV_CMOS can break userspace interface

On Sun, May 27, 2007 at 08:03:51PM +0100, Matthew Garrett wrote:

> (It doesn't really help that rtc-cmos doesn't load on this machine, but 
> I'll try to track that down later - right now I suspect some sort of PNP 
> issue)

Ah, no, it's because the ioports for the rtc-cmos driver are already 
claimed by the old driver from CONFIG_RTC. The following configuration 
is valid in Kconfig:

CONFIG_RTC=y
CONFIG_RTC_CMOS=m

but will disable /proc/acpi/wakeup. It'll also be impossible to load 
CONFIG_RTC_CMOS because CONFIG_RTC has grabbed the io ports, so it's not 
possible to use the new interface. This situation doesn't appear to be 
documented, which is less than ideal...

-- 
Matthew Garrett | mjg59@...f.ucam.org
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