Op 14-5-2012 16:16, Adam Jackson schreef:
On Sat, 2012-05-12 at 21:14 +0200, A.J. Werkman wrote:
When I boot with nomodeset boot-option in runlevel 3, I expect that I
see a login prompt on a screen with 80*25 character positions.
That's a reasonable conclusion if one's mental model is "nomodeset
disables all pre-userspace video mode changes". But that's not what it
does. nomodeset disables KMS support in the kernel. It does not affect
grub's behaviour, and it does not affect the old-style vga= options.
So...
This was default in the old days and from somewhere around f12(?) this
changed and I had to use the nomodeset argument to get this screen
dimensions in text-mode. With F16 when grub2 started in text-mode this
also was the case. But now in the later F17-TC's I see that grub2 starts
in graphical mode. And now passing the nomodeset option no longer brings
up a 80*25 text-mode screen in runlevel 3, but gives me a much smaller
lettertype and more positions on the screen vertical and horizontal.
When you do this, do you see symlinks for your video outputs
in /sys/class/drm? I suspect that you don't, that nomodeset has
disabled KMS support as expected. On that assumption, we would still
need to explain why your text console doesn't match your expectations.
I would bet that the answer is that grub2 does not reset the video mode
to 80x25 before entering the kernel, and tells the upcoming kernel what
mode it has programmed. grub2.cfg seems to agree with me: gfxpayload is
set to 'keep', at least on my machine that I didn't do anything special
to.
Pretty sure if you set gfxpayload to 'text' in addition to passing
'nomodeset' to the kernel you will get the old behaviour.
I freshly installed F17-TC5, changed gfxpayload to text and added
nomodeset to the boot options. Then I rebuild the grub config-file with
grub2-mkconfig.
Indeed I now have a 80*25 text screen on the console when I boot.
In /sys/class/drm I do see symlinks though.
Now whether that's a bug, I don't know, and kind of doubt. Fewer video
mode transitions during boot is generally preferable, and the way to do
that is to pass grub's environment to the kernel for reuse. So if you
want a graphical boot menu, you have to set that up before you know
you're going to disable KMS in the upcoming kernel, so...
Besides, 'nomodeset' is a diagnostic tool, not a support path.
- ajax
From your comment I conclude, that I more or less wrongly use
nomodeset. Can you tell me what the 'official' way is, to reach my goal?
Koos
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