[Bug 224069] (Fix included) Use of uninitalized register value in vesa.ko, causing X, text console and suspend/resume to fail

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=224069

--- Comment #8 from Stefan B. <sblachmann at gmail.com> ---
(In reply to Jung-uk Kim from comment #4, #5 and #6)

#4: Didn't know about register zeroing. Such was not common back then when I
did VGA programming via hardware and INT10 decades ago using mixed C and
assembly back in the 16-bit DOS times.
The sysctl tip is great for debugging!


#5 No, you don't deserve that at all.
When I saw the commit Mark pointed me at, I instantly recognized that it was a
lot of work involved. And you know, the bigger the work, the easier it is to
overlook a detail. See please my comment #3, too.

And I did not know you were the one who implemented FreeBSD suspend/resume.
That was great work, good to know. Thank you!
However, I think the suspend/resume thing has been neglected, and it does not 
work for many people. Below I discuss part of possible reasons.
Btw, are you still interested in improving suspend/resume from STR to STD?


#6 That is very interesting, because:
In the FreeBSD forums, there are constant complaints regarding Nvidia cards. 
Garbled display when switching between console and X, and after resume. I have
made the discovery that this apparently *only* happens when vesa.ko is present.
And that is in the GENERIC kernel or as loaded module.

In the forums I have talked much of that problem. Apparently all people that
followed my advice to build a custom kernel *without* option VESA and switch
from vt to sc console (because the default vt console pulls in vesa.ko, if not
present in kernel), got rid of these problems.

And, in my naive opinion I think suspend/resume should *not* be broken by just
doing kldload vesa.ko. (this is factually the way to reproduce the problem)

So I have the strong feeling that there is a serious problem with the vesa
module. But that is just my (possibly misleading) intuition.

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