MSI -5149 User Manual page 61

Chapter 4
Security Option
PCI VGA Palette
Snooping
4.5 Chipset Features Setup Menu
®
AWARD BIOS USER'S GUIDE
Choose "System" to prevent unauthorized
system boot-up or choose "Setup" to
prevent unauthorized use of BIOS Setup.
Choose Disabled or Enabled. Some graphic
controllers, which are not VGA compatible,
take the output from a VGA controller and map
it to their display as a way to provide the boot
information and the VGA compatibility.
However, the color information coming
from the VGA controller is drawn from
the palette table inside the VGA
controller. In order for the graphic
controller to generate the proper colors,
the graphic controller needs to know what
is in the palette of the VGA controller. To
do this , the non-VGA graphic controller
watches for Write access to the VGA
palette registers and snoops the data. In
the PCI based systems where the VGA
controller is on the PCI bus and a non-
VGA graphic controller is on the ISA bus,
the Write access to the palette will not
show up on the ISA bus if the PCI VGA
controller responds to the Writes. In this
case, the PCI VGA controller should not
respond to the write; it should only snoop
the data and permit the access to be
forwarded to the ISA bus. The non-VGA
ISA graphic controller can then snoop the
data on the ISA bus. Unless you have the
above situations, you should disable this
option.
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