HEADLESS flag in ACPI

HEADLESS flag in ACPI

[Evan Lloyd]

We have a minor conundrum, and would like an element of consensus before we make a commit.
We want to (re-)submit patches adding HDLCD/GOP for some ARM platforms.
We have previously been asked to make this optional, as some people do not want the overhead of GOP (and the frame buffer) in their image/RAM.  This is fine, and a build flag called HEADLESS would seem to fit the bill.

The query arises from the ACPI spec which has (in FADT): "
HEADLESS 1 12 System Type Attribute. If set indicates the system cannot detect the monitor or keyboard / mouse devices."

And what we need to confirm is that there is no case of a system with no display still wanting to have keyboard and/or mouse.  I can't imagine there is, but thought it best to check.

Any thoughts?


Evan

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Re: HEADLESS flag in ACPI

[Leif Lindholm]

+ MdeModulePkg maintainers (GOP), linaro-acpi, Graeme, Ard.

On Wed, Sep 13, 2017 at 12:23:01PM +0000, Evan Lloyd wrote:
> We have a minor conundrum, and would like an element of consensus
> before we make a commit.
> We want to (re-)submit patches adding HDLCD/GOP for some ARM
> platforms.
> We have previously been asked to make this optional, as some people
> do not want the overhead of GOP (and the frame buffer) in their
> image/RAM.  This is fine, and a build flag called HEADLESS would
> seem to fit the bill.
> 
> The query arises from the ACPI spec which has (in FADT): "
> HEADLESS 1 12 System Type Attribute. If set indicates the system
> cannot detect the monitor or keyboard / mouse devices."
> 
> And what we need to confirm is that there is no case of a system
> with no display still wanting to have keyboard and/or mouse.  I
> can't imagine there is, but thought it best to check.
>
> Any thoughts?

I can't think of any.

Even if your video is only accessible via BMC, that's still video.

/
    Leif

Re: HEADLESS flag in ACPI

[Zeng, Star]

There should be platform has terminal console by serial, but has no VIDEO.


Thanks,
Star
-----Original Message-----
From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Leif Lindholm
Sent: Thursday, September 14, 2017 5:21 PM
To: Evan Lloyd <Evan.Lloyd@arm.com>
Cc: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>; Dong, Eric <eric.dong@intel.com>; Ard Biesheuvel <ard.biesheuvel@linaro.org>; Marc Zyngier <Marc.Zyngier@arm.com>; Catalin Marinas <Catalin.Marinas@arm.com>; edk2-devel (edk2-devel@lists.01.org) <edk2-devel@lists.01.org>; linaro-acpi@lists.linaro.org; Stephanie Hughes-Fitt <Stephanie.Hughes-Fitt@arm.com>; Sudeep Holla <Sudeep.Holla@arm.com>; Dong Wei <Dong.Wei@arm.com>; Zeng, Star <star.zeng@intel.com>
Subject: Re: [edk2] HEADLESS flag in ACPI

+ MdeModulePkg maintainers (GOP), linaro-acpi, Graeme, Ard.

On Wed, Sep 13, 2017 at 12:23:01PM +0000, Evan Lloyd wrote:
> We have a minor conundrum, and would like an element of consensus 
> before we make a commit.
> We want to (re-)submit patches adding HDLCD/GOP for some ARM 
> platforms.
> We have previously been asked to make this optional, as some people do 
> not want the overhead of GOP (and the frame buffer) in their 
> image/RAM.  This is fine, and a build flag called HEADLESS would seem 
> to fit the bill.
> 
> The query arises from the ACPI spec which has (in FADT): "
> HEADLESS 1 12 System Type Attribute. If set indicates the system 
> cannot detect the monitor or keyboard / mouse devices."
> 
> And what we need to confirm is that there is no case of a system with 
> no display still wanting to have keyboard and/or mouse.  I can't 
> imagine there is, but thought it best to check.
>
> Any thoughts?

I can't think of any.

Even if your video is only accessible via BMC, that's still video.

/
    Leif
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