linux-kernel - Re: [PATCH 1/3] dummycon: only build module if there are users

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <fb4c9b76-82dd-4227-9ee5-d7b52438bd0e@suse.de>
Date: Thu, 27 Feb 2025 10:25:32 +0100
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Arnd Bergmann <arnd@...db.de>, Arnd Bergmann <arnd@...nel.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Helge Deller <deller@....de>
Cc: linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] dummycon: only build module if there are users

Hi

Am 26.02.25 um 12:46 schrieb Arnd Bergmann:
> On Wed, Feb 26, 2025, at 09:16, Thomas Zimmermann wrote:
>> Am 26.02.25 um 08:55 schrieb Arnd Bergmann:
>> Here's another general question. vgacon and fbcon only seem usable with
>> CONFIG_VT=y. Wouldn't it make sense to have them depend on CONFIG_VT=y?
>> dummycon could then be implemented as part of the vt code, maybe even
>> become a vt-internal thing. The console code is complex, so I'm probably
>> missing something here?
> I think in theory one may have a system use fbcon purely to get the
> boot logo, but not actually support VT.  I had also assumed there might
> be a way to use fbcon as the console (i.e. printk) but not register
> the tty, but it looks like the console code still requires vt.
>
> After I looked at the vt and conswitchp code some more, I wonder
> if we could go the other way and instead of integrating it more
> make the conswitchp logic optional: most of the complexity here
> deals with switching between text console and fbcon dynamically,
> but having any text console support is getting very rare (vga
> on alpha/mips/x86-32, newport on mips-ip22, sti on parisc).
>
> If we do this, the conswitchp code could be merged with dummycon
> in drivers/video/console, with the simpler alternative just
> calling into fbcon functions. I'm not sure if we can already drop
> vgacon from normal x86-64 distro configs, i.e. if there are cases
> that are not already covered by any of efi-earlycon, efifb,
> vga16fb, vesafb/uvesafb or a PCI DRM driver.

Thanks for the lengthy answer. I don't want to add work to your todo 
list. For vgacon, I wouldn't remove it yet, as there still exisits 
x86_64 systems with plain VGA support.

Best regards
Thomas


>
>      Arnd
>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)