From mboxrd@z Thu Jan 1 00:00:00 1970 From: Catalin Marinas Subject: Re: [Linaro-acpi] [PATCH v7 04/17] ARM64 / ACPI: Introduce early_param for "acpi" and pass acpi=force to enable ACPI Date: Wed, 28 Jan 2015 18:08:16 +0000 Message-ID: <20150128180816.GF31752@e104818-lin.cambridge.arm.com> References: <1421247905-3749-1-git-send-email-hanjun.guo@linaro.org> <1421247905-3749-5-git-send-email-hanjun.guo@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Timur Tabi Cc: Mark Rutland , Rob Herring , "phoenix.liyi@huawei.com" , Robert Richter , "linux-acpi@vger.kernel.org" , Arnd Bergmann , "linaro-acpi@lists.linaro.org" , Marc Zyngier , Will Deacon , Randy Dunlap , "Rafael J. Wysocki" , lkml , "grant.likely@linaro.org" , "wangyijing@huawei.com" , Mark Brown , "hanjun.guo@linaro.org" , "jcm@redhat.com" , Olof Johansson , Bjorn Helgaas , "linux-arm-kernel@lists.infradead.org" , Jason Cooper List-Id: linux-acpi@vger.kernel.org On Wed, Jan 28, 2015 at 05:58:54PM +0000, Timur Tabi wrote: > On Wed, Jan 14, 2015 at 9:04 AM, Hanjun Guo wrote: > > From: Al Stone > > > > Introduce one early parameters "off" and "force" for "acpi", acpi=off > > will be the default behavior for ARM64, so introduce acpi=force to > > enable ACPI on ARM64. > > > > Disable ACPI before early parameters parsed, and enable it to pass > > "acpi=force" if people want use ACPI on ARM64. This ensures DT be > > the prefer one if ACPI table and DT both are provided at this moment. > > What is the reason to assume that DT is preferred over ACPI? I would > have thought that if ACPI is present, then it means we're on an ARM64 > server platform, and therefore it should be used. It seems silly to > require acpi=force on every ARM64 server platform. I'm against requiring acpi=force when *only* ACPI tables are present (I don't like a command line argument to become firmware-kernel ABI), but otherwise DT takes precedence (it was the first supported booting method on arm64 and currently it is more mature and feature-rich than ACPI on arm64). -- Catalin