[coreboot] VGA and Graphics

[Igor Skochinsky]

Hello Zoran,

Monday, April 3, 2017, 9:24:41 AM, you wrote:


> VBT is not code, it's a table -- that's what the T is -- and you can create it any way you want.

Not going to say more, anyway. Just to point to the standard:
https://en.wikipedia.org/wiki/VESA_BIOS_Extensions


Not sure why you posted this link. VBE is not VBT, it's a completely separate and different thing.



To clever enough! ;-)

Zoran

On Mon, Apr 3, 2017 at 2:38 AM, ron minnich <rminnich at gmail.com> wrote:
As for graphics startup, here's what I learned when I was doing this in 2012/2013: the kernel could start sandy and ivy with no vbios needed. However, I have been told that the veil of secrecy has started to draw a bit closer in subsequent chipsets, and that something like a VGA BIOS/GOP has to run or graphics will not work. I really don't know, I have not looked at this in over 3 years.

Todd, just to make sure we're on the same page, VBT is not code, it's a table -- that's what the T is -- and you can create it any way you want. 

Also, as for numbers: the fastest graphics startup, by far, was when we had coreboot- based startup with configuration specialized to the chromeos laptop. How fast? At one point we had a pixel booting to chromeos prompt in 2.7 seconds, reduced from 7.7 seconds when linux did the graphics init. We've seen that the linux graphics init is highly concurrent and generalized, and that tends to mean slow. Of course this was all far faster than the 8086-mode vga BIOS supplied by "the vendor". But we were a bit surprised to see how much faster coreboot was than the linux kernel. 

I doubt this speed difference matters any more, since boot time only needs to be "fast enough" nowadays and 10 seconds seems to do it for most people -- plus, any 5-second advantage in boot time vanishes as soon as you go to your first web page.

ron



On Sun, Apr 2, 2017 at 5:31 PM ron minnich <rminnich at gmail.com> wrote:
So, I'll mention go userland one last time, for a simple reason: I have it on good authority that at some places, saying you have a go userland instead of a c userland checks a check box on a security checklist. I think that's a sensible decision, having watched all the awful ways that C programs tend to go wrong :-)

ron

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-- 
WBR,
 Igor
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