linux-kernel - Re: [REGRESSION] boot-screen override by "34db50e55656 efifb: Copy the ACPI BGRT"

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Date:   Wed, 12 Sep 2018 11:13:35 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     David Herrmann <dh.herrmann@...il.com>
Cc:     Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-fbdev@...r.kernel.org, linux-efi@...r.kernel.org,
        dri-devel@...ts.freedesktop.org
Subject: Re: [REGRESSION] boot-screen override by "34db50e55656 efifb: Copy
 the ACPI BGRT"

Hi,

On 03-09-18 17:11, David Herrmann wrote:
> Hey
> 
> On Mon, Sep 3, 2018 at 4:47 PM Hans de Goede <hdegoede@...hat.com> wrote:
>>
>> Hi,
>>
>> On 03-09-18 16:16, Bartlomiej Zolnierkiewicz wrote:
>>>
>>> Hi,
>>>
>>> On Monday, September 03, 2018 03:23:38 PM David Herrmann wrote:
>>>> Hey
>>>>
>>>> Since this commit:
>>>>
>>>>       34db50e55656 efifb: Copy the ACPI BGRT
>>>>
>>>> the kernel will override boot-splashs unasked. This breaks the
>>>> graphical boot-process on our setups. In particular, we have a setup
>>>> where an efi-boot-entry draws the early boot-splash on-screen, then
>>>> hands-over to the linux-kernel + initrd. The boot-splash daemon in the
>>>> initrd then takes over control of possible animations.
>>>>
>>>> With the mentioned commit compiled in, the kernel will redraw the
>>>> firmware logo on screen at a random time without any way to intervene.
>>>
>>> You have CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER=y (the deferred
>>> console takeover support introduced in v4,19-rc1). I assume that this
>>> is intended?
>>>
>>>> What is the intention of this commit? Why is the kernel re-drawing the
>>>> firmware logo unasked? If someone during the boot-process draws
>>>> content on the screen, I would prefer if the kernel does not clear
>>>> that on driver load.
>>>
>>> +/*
>>> + * If fbcon deffered console takeover is configured, the intent is for the
>>> + * framebuffer to show the boot graphics (e.g. vendor logo) until there is some
>>> + * (error) message to display. But the boot graphics may have been destroyed by
>>> + * e.g. option ROM output, detect this and restore the boot graphics.
>>> + */
>>> +#if defined CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER && \
>>> +    defined CONFIG_ACPI_BGRT
>>> ...
>>> +static void efifb_show_boot_graphics(struct fb_info *info)
>>> ...
>>> +#else
>>> +static inline void efifb_show_boot_graphics(struct fb_info *info) {}
>>> +#endif
>>>
>>>> Can we either provide an option to disable this feature, or revert the commit?
>>>
>>> Hans?
>>
>> We use the ACPI bgrt extension to get the logo to draw and then
>> draw it since some devices rely on the OS to draw it and otherwise we
>> just end up with a blackscreen when doing silent / flickerfree boot.
>>
>> Ideally you would be able to get your vendor to put the logo in firmware
>> in the ACPI bgrt extension, then you also do not need to play any tricks
>> with an EFI binary drawing your own logo. But I can understand if you don't
>> have control over this, so you need to do this with the EFI binary trick.
>>
>> I can also understand that you want to use deferred console takeover
>> in a setup like yours to avoid fbcon messing up what is on the display
>> during boot, that is exactly what it is for. So I think a reasonable
>> approach here is to add a kernel commandline option, say:
>>
>> video=efifb:nobgrt
>>
>> David, would that work for you?
> 
> That would be perfect!

Ok, I just send out a patch for this with you in the Cc.

Sorry for taking a bit long to write the patch.

Regards,

Hans