34

I wonder what vt.handoff=7 parameter does. I can not find any good man entries for that...

BTW, if you have a nice description about:

search --no-floppy --fs-uuid --set=root

I would be very happy :)

grub.cfg example:

menuentry 'FAILSAFE' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
set gfxpayload=$linux_gfx_mode
insmod part_msdos
insmod ext2
set root='(hd0,msdos8)'
search --no-floppy --fs-uuid --set=root 36286167-4eba-4a1e-a202-155c6baafa01
linux /boot/vmlinuz-2.6.37-12-generic root=UUID=36286167-4eba-4a1e-a202-155c6baafa01 ro vt.handoff=7 quiet splash
initrd /boot/initrd.img-2.6.37-12-generic
}

BTW2 - i can not create tag vt.handoff ;(

David Foerster
  • 36,264
  • 56
  • 94
  • 147
sirkubax
  • 341
  • 3
    Welcome to Ask Ubuntu! We're sorry, but Ask Ubuntu is not a forum, but a Question & Answer site: it works best if you ask one question, so you can receive one answer. When you ask multiple questions, you need to find one expert versed in multiple areas, which becomes unlikelier the more questions you put into, well, one question! ;-) So please, split up your question into multiple questions and drop me a comment so I can answer one of your questions. – David Foerster Oct 17 '15 at 14:20

1 Answers1

47

For a smooth boot process, we want to display something other than a black screen as early as possible and leave it on screen until the desktop is ready. vt.handoff=7 is part of this. We have the boot loader display an aubergine background (we wanted to have an Ubuntu logo as well, but there are problems with different aspect ratios between the boot loader and the real system, so this is the next best thing). vt.handoff=7 then causes the kernel to maintain the current contents of video memory on virtual terminal 7, which is a new "transparent" VT type. The first time that the kernel is told to switch away from VT 7, either from Plymouth or manually (Alt-F1, etc.), these contents are lost and VT 7 reverts to text mode.

The upshot is that, when everything is working correctly, you get an aubergine background on the way out of the boot loader, then at some point Plymouth displays a logo and a progress indicator on top of that, and then the display manager comes up and smoothly replaces that with a login prompt.

Also, you asked about the search command in GRUB. That is documented in the GRUB manual.

Colin Watson
  • 6,340
  • How i may sacefully unable the option "vt.handoff=7" from my grub.cfg configuration,so,that be it never adding again? –  Mar 28 '12 at 16:35
  • @deblanck: Edit /etc/grub.d/10_linux as explained here – Serrano Pereira May 21 '12 at 15:01
  • 1
    So this is separate from the gfxpayload=keep option in GRUB? i.e. if you get a desirable graphics mode in GRUB menu, and you get the aubergine blank screen and the correct desktop but get "Mode Not Supported" instead of the Plymouth splash, then this is Plymouth's fault? – Sam Brightman Sep 12 '15 at 12:04
  • 1
    gfxpayload=keep and vt.handoff=7 are two parts of the same overall scheme; gfxpayload=keep tells GRUB not to switch the video mode back to the firmware default before booting the kernel, and vt.handoff=7 tells the Linux kernel to behave as in my answer above. I don't know where your error message comes from. – Colin Watson Sep 13 '15 at 11:05
  • If vt.handoff is assigned 3, will one boot into command line mode (no X)? – user1823664 May 02 '18 at 03:08
  • @user1823664, I think you've confused the old distro-specific runlevel 3 (which was a "no X" runlevel on Red Hat and its derivatives, but not on Debian and its derivatives) with virtual terminal numbers. vt.handoff=3 would simply tell the kernel to maintain the current contents of video memory on virtual terminal 3 at startup; this might happen to confuse something into booting without X, but if it does it would be an accident at best. – Colin Watson Jun 25 '18 at 13:21
  • 1
    @guntbert that one is dead too... – Maxim Blinov Sep 23 '20 at 01:37