HDMI output since boot?

Ginta · Apprentice Joined: 17 Feb 2006 Posts: 152 Location: Spain

I have a laptop with a broken screen, but it usually boots, and when KDM is started, then, HDMI is detected and used, so I can use it.

But my problem is that I am afraid that maybe one day, some update or bad config could have my system unbootable and I could not do much without an active screen.

That's why I thought on the posibility of booting directly to HDMI (like some framebuffer or something similar) in early kernel boot stage.

The problem: I don't have a clue if it is possible, which kernel config should I have, or which special option to kernel boot parameters should I use

Currently, I use grub2, with this lines on /etc/defaults/grub

GRUB_GFXPAYLOAD_LINUX=1920x1080x24
GRUB_DISTRIBUTOR="Gentoo"
GRUB_TIMEOUT=10
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_DEFAULT=saved
GRUB_GFXMODE=1920x1080x24
GRUB_CMDLINE_LINUX_DEFAULT='root=/dev/sda2 video=uvesafb:1920x1080-32,mtrr:3,ywrap crashkernel=128M@16M resume=/dev/sda4 udev splash rw'
#GRUB_HIDDEN_TIMEOUT=0
GRUB_TERMINAL=console

Maybe changing video=uvesafb:1920x1080-32 to something else could work, but unfortunatelly I can't just test, because if it does not boot, it is very hard to repair it.

I will thank any comment on it

P.S. I use nvidia-driver if it is needed to know
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Some people should use emerge brain on theirselves...

Logicien · Posted: Fri Apr 18, 2014 6:16 pm Post subject:

If you want to boot only from your external Hdmi screen, you can tell Linux to do so. You do not need more than one video parameter, This should do the job:

Ginta · Apprentice Joined: 17 Feb 2006 Posts: 152 Location: Spain

Logicien · Posted: Sat Apr 19, 2014 12:38 am Post subject:

All videos output use to be enabled by default by the Linux kernel. Passing

Ginta · Apprentice Joined: 17 Feb 2006 Posts: 152 Location: Spain

Oh, that makes sense.

However, I've tried and the result is just the same, hdmi output is not enabled until KDE starts and I can't see the tty in my TV yet.

Maybe I miss some kernel options, or maybe my hardware is just unable to do it in boot phase?
_________________
Some people should use emerge brain on theirselves...

Logicien · Posted: Sun Apr 20, 2014 3:20 pm Post subject:

Note that the kernel log will give you the exact port number for LVDS-? and HDMI-? Check with dmesg.
Try to boot with these kernel parameters

s4e8 · Guru Joined: 29 Jul 2006 Posts: 311

You have no output control if you use the nvidia-driver, both VGA/VESA console output initialized by BIOS.