linux-kernel - Re: [PATCH] video/console/vgacon: Print big fat warning with nomodeset

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Message-ID: <87a7r8r0q3.fsf@intel.com>
Date:   Tue, 03 Jul 2018 14:57:08 +0300
From:   Jani Nikula <jani.nikula@...ux.intel.com>
To:     Daniel Vetter <daniel@...ll.ch>, Lyude Paul <lyude@...hat.com>
Cc:     linux-fbdev@...r.kernel.org, Kees Cook <keescook@...omium.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Jan H. Schönherr 
        <jschoenh@...zon.de>, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH] video/console/vgacon: Print big fat warning with nomodeset

On Tue, 03 Jul 2018, Daniel Vetter <daniel@...ll.ch> wrote:
> On Mon, Jul 02, 2018 at 05:04:40PM -0400, Lyude Paul wrote:
>> It's been a pretty good while since kernel modesetting was introduced.
>> It has almost entirely replaced previous solutions which required
>> userspace modesetting, and I can't even recall any drivers off the top
>> of my head for modern day hardware that don't only support one or the
>> other. Even nvidia's ugly blob does not require the use of nomodeset,
>> and only requires that nouveau be blacklisted.
>> 
>> Effectively, the only thing nomodeset does in the year 2018 is disable
>> your graphics drivers. Since VESA is a thing, this will give many users
>> the false impression that they've actually fixed an issue they were
>> having with their machine simply because the laptop will boot up to a
>> degraded GUI. This of course, is never actually the case.
>> 
>> Things get even worse when you consider that there's still an enormous
>> amount of tutorials users find on the internet that still suggest adding
>> nomodeset, along with various users who have been around long enough to
>> still suggest it.
>> 
>> There really isn't any legitimate reason I can see for this to be an
>> option that's used by anyone else other then developers, or properly
>> informed users. So, let's end the confusion and start printing warnings
>> whenever it's enabled.
>> 
>> Signed-off-by: Lyude Paul <lyude@...hat.com>
>
> Yeah makes tons of sense. I think we should also perhaps mark the option
> as a tainting one, but I think that's only wired up for module option.

You could do that by adding

	add_taint(TAINT_USER, LOCKDEP_STILL_OK);

in text_mode(). If you do that, you should probably amend the warning
message accordingly.

Either way,

Acked-by: Jani Nikula <jani.nikula@...el.com>

> Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>
>
>> ---
>>  drivers/video/console/vgacon.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>> 
>> diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
>> index f09e17b60e45..09731b2f6815 100644
>> --- a/drivers/video/console/vgacon.c
>> +++ b/drivers/video/console/vgacon.c
>> @@ -112,6 +112,11 @@ EXPORT_SYMBOL(vgacon_text_force);
>>  static int __init text_mode(char *str)
>>  {
>>  	vgacon_text_mode_force = true;
>> +
>> +	pr_warning("You have booted with nomodeset. This means your GPU drivers are DISABLED\n");
>> +	pr_warning("Any video related functionality will be severely degraded, and you may not even be able to suspend the system properly\n");
>> +	pr_warning("Unless you actually understand what nomodeset does, you should reboot without enabling it\n");
>> +
>>  	return 1;
>>  }
>>  
>> -- 
>> 2.17.1
>> 
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel@...ts.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Jani Nikula, Intel Open Source Graphics Center

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