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Subject: Re: [PATCH] acpi, spcr: Make SPCR available to x86
To:     Timur Tabi <timur@codeaurora.org>,
        Peter Zijlstra <peterz@infradead.org>
References: <20180118150951.28964-1-prarit@redhat.com>
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Cc:     linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org,
        linux-doc@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-pm@vger.kernel.org, linux-serial@vger.kernel.org,
        Bhupesh Sharma <bhsharma@redhat.com>,
        Lv Zheng <lv.zheng@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>, x86@kernel.org,
        Jonathan Corbet <corbet@lwn.net>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>, graeme.gregory@linaro.org,
        mark.salter@redhat.com
From:   Prarit Bhargava <prarit@redhat.com>
Message-ID: <7bd5897f-d6da-7e29-29c4-aa26d24f6355@redhat.com>
Date:   Mon, 12 Feb 2018 09:49:47 -0500
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On 02/12/2018 09:43 AM, Timur Tabi wrote:
> On 2/12/18 7:47 AM, Prarit Bhargava wrote:
>> ACPI SPCR is used by a vendor to define the serial console for a system.  If
>> SPCR exists a user can add kernel parameter "earlycon" (no extra kernel
>> parameters) and the console will work out-of-the-box.
> 
> "earlycon" is needed only for an *early* console.  You don't need any command
> line parameters for a normal console to work with SPCR.

That's true on ARM64.  I specifically did not enable the console by default on
x86.  There are users who do not want a console active during boot & runtime.

P.

>