[syslinux] not sure how to get rid of white screen during boot

[Douglas McClendon]

On 02/19/2011 06:40 PM, H. Peter Anvin wrote:
> On 02/19/2011 03:17 PM, Douglas McClendon wrote:
>> I've noticed in the last roughly year, something seems to have changed
>> with with the syslinux/isolinux I've been using, causing there to be an
>> unwanted flash of pure white just at the threshold of isolinux starting
>> linux.  I'm using vesamenu.c32, and have played around a bit with the
>> dozen or so color options.  I half suspect perhaps this is a linux KMS
>> caused thing.  Though one thing that makes me less(or more?) suspicious
>> of that is the fact that the white appears to be due to console text
>> background color in linux, in that I've seen the white persist exactly
>> to the first character of console text I see from linux, as if it is a
>> console text property, reset when I first output something such that
>> there is half a screen of white above if, then text with normal white on
>> black.
>>
>> The easiest way (perhaps) to reproduce this, is to just download the
>> fedora-12 and fedora-14 i686 livecd iso images, and run them under qemu.
>>    With f12, the first thing you see after you think isolinux is done, is
>> a black screen with an underline cursor in the upper left.  With f14,
>> you get the IMHO less nice full screen flash of white.  This is also
>> visible on hardware, e.g. my netbook, though the duration will be
>> subsecond versus longer than a second under qemu.
>>
>> I can do more digging, but hope that someone can give me the quick
>> explanation off the top of their heads.  I did scan the archives of the
>> list a few months back, and saw the comment about 'vga=keep' or
>> whatever, which made me think this is possibly a KMS thing, but maybe
>> the same way the font persists to linux, so do console text settings?
>
> This seems to happen when you use "quiet" but not "vga=current".

Interesting.  I had tried that and sort of given up on it because under 
qemu(0.11.1) it seemed hung, although disk i/o indicated otherwise.  So 
I tried again and discovered that at GDM, linux/fedora/mydistro does get 
working with graphics again.  And then I tried on my netbook, and there 
at least, that does basically achieve the desired effect.

But- even on real hw, there was a significant (2s-ish) delay after 
historically syslinux would have transitioned from its background, to 
linux's black console (with cursor).  Which is reasonable enough as 
clearly linux is just keeping the current graphics contents for a few 
seconds.  But- a significant improvement it would seem would be a 
fadeout effect on syslinux's part, such that the user experience can be 
better.  I.e. syslinux screen contents off the screen at the time in 
which it is out of the picture execution-wise, and then black (or 
configured screen color) to whatever the OS wants to do (plymouth 
bootsplash).

Should something like that be my reasonable long-term perfectionist hope 
for LiveCD/DVD/USB boot experience, or ??

Do I implement that by-? digging into whatever code makes up vesamenu.c32?

And of course, while I'm more concerned with the perfect real-hw netbook 
boot experience, I'd also like the qemu/virt bootup to be the same.  Any 
ideas on that?  For all I know it may be working better in current qemu 
(0.11.1 is still the recommended branch for x86-32 with no cpu hw virt 
support).

-dmc