[NTOS:INBV] Don't touch VGA I/O ports when /NOGUIBOOT specified

[binarymaster]

Don't touch VGA I/O ports when /NOGUIBOOT specified.

JIRA issue: CORE-14625, CORE-16222

[HBelusca]

See comments.

[HBelusca]

Note to self #1: InbvDisplayState is by default initialized to INBV_DISPLAY_STATE_DISABLED...
Note to self #2: We first call InbvEnableBootDriver(!NoGuiBoot), then InbvDriverInitialize().

[HBelusca]

Does BSOD still display OK later on? (because if VidInitialize is not called it won't be possible to display it)
And since this function is in the INIT section (and thus unavailable for later) I claim we still need to call it in any case (and thus potentially playing with video registers) even if NOGUIBOOT is specified.
Indeed two observations:

• NOGUIBOOT only means No GUI at boot, but you can still have "GUI" (graphics mode) for InbvDisplayString calls for later (for example, BSODs).
• When InbvDisplayState is == INBV_DISPLAY_STATE_DISABLED, which is the case when InbvEnableBootDriver() has been previously called with its parameter set to FALSE (when NOGUIBOOT is specified), the ResetMode variable here is kept to FALSE, and according to the code of VidInitialize() : https://git.reactos.org/?p=reactos.git;a=blob;f=drivers/base/bootvid/i386/bootvid.c;hb=af0d1d2f98749ed382ab7e718b91a9f11fd8a073#l361 , only HAL functions are called to find VGA memory mapping; VGA registers are only used by VgaIsPresent(), but this helper should not change the video mode, and finally, since SetMode is FALSE , bootvid does not reset the screen.

[binarymaster]

NOGUIBOOT only means No GUI at boot, but you can still have "GUI" (graphics mode) for InbvDisplayString calls for later (for example, BSODs)

I didn't know that, I thought it allows to fully disable bootvid for headless machines. I confirmed that Windows XP does initialize bootvid with NOGUIBOOT, so I close this.