From this question, about
The newest kernels have moved the video mode setting into the
kernel. So all the programming of the hardware specific clock rates
and registers on the video card happen in the kernel rather than in
the X driver when the X server starts.. This makes it possible to have
high resolution nice looking splash (boot) screens and flicker free
transitions from boot splash to login screen. Unfortunately, on some
cards this doesn't work properly and you end up with a black screen.
Adding the nomodeset parameter instructs the kernel to not load video
drivers and use BIOS modes instead until X is loaded.
From Unix & Linux, on
The splash (which eventually ends up in your /boot/grub/grub.cfg )
causes the splash screen to be shown.
At the same time you want the boot process to be quiet, as otherwise
all kinds of messages would disrupt that splash screen.
Although specified in GRUB these are kernel parameters influencing the
loading of the kernel or its modules, not something that changes GRUB
behaviour. The significant part from GRUB_CMDLINE_LINUX_DEFAULT is
This answer covers
In general, such boot parameters are not needed unless there is a
problem with your BIOS and how it handles these standards, or it just
might be old enough where these standards were not fully implemented
ACPI (Advanced Configuration and Power Interface) is a standard for
handling power management. Older systems may not support ACPI full, so
sometimes it helps to give the kernel a hint to not use it. "acpi=off"
APIC (Advanced Programmable Interrupt Controller) is a kind of feature
found on newer systems. The "local" version is called "LAPIC". What
this controller can do is be set up to generate and handle interrupts,
a signal the hardware uses to pass messages. Again, some
implementations of APIC can have problems on older system, and so it
is useful to disable it. "noapic" and "nolapic".
Sometimes the APIC is working, but it slows things down by getting in
the middle of messages being passed around. This can mess with audio
and video processing, for example. Folks might disable it for that
reason as well.