Embedded Linux 1-Second Cold Boot To QT

An anonymous reader writes "The blog post shows an embedded device cold booting Linux to a QT application all in just one second. This post also includes a link which describes what modifications were made to achieve this."

Re:Ermm..

[buchner.johannes]

The have a slideshow here: http://www.slideshare.net/andrewmurraympc/elce-the [slideshare.net] , it's interesting starting at slide 19. Especially the executable reordering to defer loading of UI event handling code is impressive.

Re:Ain't that qute?

[countSudoku()]

I had the same reaction. The answer lies in the wikipedia, not in the unhelpful intermediate posts:

http://en.wikipedia.org/wiki/Qt_(framework) [wikipedia.org]

Qt "is a cross-platform application framework that is widely used for developing application software with graphical user interface (GUI) (in which case Qt is referred to as a widget toolkit when used as such), and also used for developing non-GUI programs such as command-line tools and consoles for servers"

Re:Details

[Anonymous Coward]

Any details on what they've done? Is it largely hardware-specific initialisation, or have they made changes that would be useful on a traditional desktop?

From the article:

"We've not applied any specific intellectual property but instead spent time analysing where boot delays are coming from and simply optimising them away. The majority of the modifications we make usually fall into the category of 'removing things that aren't required', 'optimising things that are required', or 'taking a new approach to solving problems' and are tailored very precisely to the needs of the 'product'."

Also:

"If you're interested in exactly what modification I made and a little more about the approach taken - you may be interested in these slides [http://www.slideshare.net/andrewmurraympc/elce-the] which I presented at ELC-E 2010"

Re:Function re-ordering inside the image? wow

[Chrutil]

That's actually common practice in profile guided optimization, put commonly used code close together in the image to minimize the number of pages loaded.

Re:Function re-ordering inside the image? wow

[noidentity]

Really? I thought this was standard stuff for profile-guided-optimization. It's common knowledge that when a system initializes, it jumps all over the image, which is bad if it's paged. Seems a big "duh" to reorder functions so that all the init code is together.

Another optimization that was common old Mac compilers was "dead-stripping", where they avoided linking in any functions that were never called. Apparently this isn't commonly done and instead if a single function in a file is called, then ALL are linked in, at least when I looked into it for Linux a while back.

Re:yes, my 1990 Acorn A3000...

[thegarbz]

Actually if you custom compile your kernel to strip out every device driver that's irrelevant to your system you will save an absolute trivial amount of boot time at best. Go to TFA and click the slideshow to see where the real slogs of the boot lie.

Re:Function re-ordering inside the image? wow

[sp332]

The Story of Mel! http://foldoc.org/The+Story+of+Mel [foldoc.org] (That's not the original, that's the "free verse" version which is better IMHO.) It might even be a true story! http://en.wikipedia.org/wiki/Mel_Kaye [wikipedia.org]

Re:Flash 9

[frogboyflips]

There is also a PDF of the slides on the elinux.org web site under the 'Boot Time' page.

PDF is available here

[lindi]

My thoughts exactly, I don't want to use non-free adobe flash and slideshare does not work with gnash. Fortunately a very similar looking PDF does seem to be available at

http://elinux.org/images/f/f7/RightApproachMinimalBootTimes.pdf