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Is there any meaning of the CentOS (I guess RedHat and if I remember correctly Fedora too) boot screen progress bar layers*?

CentOS boot screen progress bar
(*) Layers ~ white, lilac(?) and violet colours.

I can't figure out any good search query for this, but maybe somebody will know...

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    I had always assumed it was meant to indicate "hey look at me, I'm moving around." The source code seems to bear that out(that's from the function that updates the "step bar"). Although maybe someone knows more than me.
    – Bratchley
    Jan 20, 2016 at 19:58
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    It is an illusion, mental imagery of sorts. The point is to make the boot feel faster whilst looking at the screen.
    – Runium
    Jan 20, 2016 at 20:31

2 Answers 2

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+50

I'm not an expert, but from the source (ply-text-progress-bar.c) it looks like you set the overall percentage done and that the different colors/layers's progress is hard coded by the following, and other functions within that file:

    brown_fraction = -(progress_bar->percent_done * progress_bar->percent_done) + 2 * progress_bar->percent_done;
    blue_fraction = progress_bar->percent_done;
    white_fraction = progress_bar->percent_done * progress_bar->percent_done;

So, it appears that it is a style choice with no underlying meaning.

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  • lol brown = 2*percent - percent^2, blue = percent, white = percent^2. Lame Plymouth, lame. I'll accept this as a definitive answer though.
    – Mike Ounsworth
    Jun 15, 2016 at 20:55
  • @MikeOunsworth Thank you for the bounty... I have been too lazy or not enough curios to look to the code, but fortunately Liczyrzepa answered this.
    – g2mk
    Jun 16, 2016 at 16:59
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    It's funny - I had wondered myself what was behind that progress bar and was curious. When I saw the question posted here, I thought to myself, time to figure it out! Thanks for spurring my curiosity :)
    – Liczyrzepa
    Jun 16, 2016 at 18:08
  • @Liczyrzepa Thanks for your answer, however IMO it's a pity that opportunity to show something meaningful on this progress bar is wasted.
    – g2mk
    Jun 16, 2016 at 20:26
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The software that is running to produce that bar is called Plymouth, and it only appears if you have rhgb in your kernel arguments. It basically takes the output of the startup sequence and presents it according to the chosen theme. In this case, it is using the text theme, probably because it can't start the graphical theme.

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  • I'm aware that is startup sequence progress, I have found that is Plymouth and I prefer text mode ;) Just since I have seen it first time I'm wondering is the darkest layer a kind of task scheduling progress, medium a kind of task execution start and a brightest a task execution end or the layers just don't have any meaning (what Sukminder suggests).
    – g2mk
    Jan 23, 2016 at 11:51

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