What happens if I make grub the default boot loader, then delete Ubuntu
What happens if I make grub the default boot loader, then delete Ubuntu
Noah Ross
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Lucas Powell
Nothing, grub is directly installed on the BIOS/UEFI
Gabriel Lopez
This guy is retarded.
grub is generally installed on the MBR of your main HDD/SSD, with additional files being loaded from "/boot/grub"
David Gonzalez
You know, I never really understood how MBR bootloaders work. Sure, I understand that the bios checks the MBR and executes code from it, but it obviously isn't enough to load an entire OS or even a boot menu like that.
But it's also not enough to make a driver for an ext4 partition in order to load files from it.
So how does grub load its second stage bootloader? First I thought it could just memorize the exact sector and then use bios IO to read it into memory, but that would break as soon as someone defragmented the drive.
Nathan Perry
afaik what is written to the MBR by grub is little more than a pointer to the actual bootloader on the disk. The bootloader only loads the kernel (Linux/NT) and the kernel initializes the rest of the components of the OS.
The MBR itself can't be defragmented, and any defragmentation program will update file pointers while moving files.
Mason Smith
Yes, but how does it load the second stage from the MBR? That would require writing an ext4 driver in the mbr, but there's not enough space for that.
Dominic Campbell
it would be extremely painful
Joshua Garcia
With the power of machines these days, why are bootloaders so fucking ugly? Never the native resolution of your display and they look fucking garbage.
Blake Robinson
because they're supposed to just boot and not do anything else, they're not here to be pretty
you can set a minimal bootloader time to hide it, or you can set it to 0
Brody Morgan
It doesnt you stupid twat
like the previous answer. Grub is merely a pointer to the bootloader. Think of it like a signpost pointing to a town
then the car driver can choose one way or another
Henry Wilson
use grub-customizer n00b
Charles Roberts
And where is that bootloader stored? How does the code in the mbr adress it realiably so it can jump to it?
That's the question.
Ryder White
it's working at a lower level than the filesystem. Your filesystem doesn't even come into play until the kernel is loaded
Thomas Wood
WHAT level?
That's precisely the part every article that attempts to describe the boot process just skips over.
Robert Perez
see
Thomas Richardson
magic numbers nigga
Angel Watson
the same level of the partition table and MBR. Both the BIOS and bootloader essentially load raw data from a point on the disk into memory for the CPU to execute.
Brayden Hughes
what I'm trying to say is that the bootloader loads data from the disk in the same way the BIOS does
Colton Ramirez
Basically. Low level computing shit fucks with your head
Nathaniel Ramirez
These non-answers are precisely why we never have actual discussion about technology on Jow Forums.
>How does Grub load its second stage? Where is it stored? How does it know where it's stored despite having no filesystem access?
>Uhh, iunno, like, some low level stuff or something, there, that answers it.
Eli Morales
>How does it know where it's stored despite having no filesystem access?
A filesystem isn't necessary for accessing data on a disk, which was already said.
Asher Green
Just don't touch the /boot partition and you will be fine.
Then press 'e' and delete the Ubuntu entries of your bootloader.
Connor Reyes
This. The disk has it's own microcontroller which can be told what to do at a basic level.
"read data from point XX to YY"
"write data from point XX to YY"
Brandon Taylor
for you, maybe
Alexander White
And yet that doesn't answer the question. It's like answering
>How does machine learning work
with
>Uhh, the CPU executes instructions and that causes values to change.
Colton Morris
It's nothing like that.
The filesystem is on a completely different level of operation. At this level it literally is just telling the disk to load some specific bits for the processor to execute. The microcontroller on the disk knows where the data is stored for a given address.
Leo Watson
Pic related happens
Carter Lewis
>Never the native resolution of your display
Because you didn't configure grub properly
Aiden Peterson
meant for
Jason Wright
The MBR is the first 512 bytes of the disk. It begins with a tiny bit of assembly explaining which physical location to jump to ie the first active partition. All MBR partitions in their first sector contain another small chunk of code that again points to a physical location (this time I think it is an offset from the start of the partition). This chunk of code this points to can actually be as large as is necessary, but it's still raw assembly - 1's and 0's on the disk outside of the filesystem of the partition.
But since this sector can be as large as needed it has enough space to implement the driver for your filesystem eg ext4 and find, load and run the boot up code for your os.
Aiden Mitchell
non-amp link neosmart.net