Re: [PATCH] video: console: mdacon: remove this obsolete driver

[Helge Deller <deller@gmx.de>]

On 5/20/26 05:31, Ethan Nelson-Moore wrote:
> The mdacon driver supports using ISA MDA or Hercules-compatible display
> adapters as a secondary text console. This was commonly used in the
> 1990s and earlier for debugging software which took over the primary
> display. It is highly unlikely anyone is doing so nowadays because
> serial consoles and much better methods of debugging exist.
> 
> The driver is not enabled by any defconfig, nor any of the
> dozens of distro configs collected at [1]. It has been relegated to VTs
> 13-16 since commit 0b9cf3aa6b1e ("mdacon messing up default vc's - set
> default to vc13-16 again") in Linux 2.6.27 (and before Linux 2.5.53 -
> see the link in the message of the above commit). The change in 2.6.27
> was done because it was incorrectly detecting non-MDA adapters as MDA
> and taking over all VTs, rendering them unusable.
> 
> Furthermore, vgacon supports using MDA/Hercules-compatible adapters as
> the primary text console, so any systems with only one of these
> adapters were already using vgacon and will not experience any loss in
> functionality from the removal of this driver.
> 
> Given all of these factors, the mdacon driver is likely entirely
> unused. Remove it.

I've applied this patch to the fbdev git tree, since I also believe that
there is no use case or user left (with Linux kernels >= 7.0), which uses the mdacon.

If someone thinks we need to keep it, please speak up.

Helge


> 
> [1] https://github.com/nyrahul/linux-kernel-configs/tree/f0bee86a135a0406ea427855f52702dd00d770f9
> 
> Signed-off-by: Ethan Nelson-Moore <enelsonmoore@gmail.com>
> ---
>   .../admin-guide/kernel-parameters.txt         |   5 -
>   arch/alpha/kernel/io.c                        |   2 +-
>   arch/powerpc/include/asm/vga.h                |   4 +-
>   drivers/tty/vt/vt.c                           |   3 -
>   drivers/video/console/Kconfig                 |  15 -
>   drivers/video/console/Makefile                |   1 -
>   drivers/video/console/mdacon.c                | 566 ------------------
>   include/linux/console.h                       |   2 -
>   include/linux/vt_buffer.h                     |   2 +-
>   9 files changed, 4 insertions(+), 596 deletions(-)
>   delete mode 100644 drivers/video/console/mdacon.c