From: Steve Litt via Talk <talk@lists.gtalug.org>
D. Hugh Redelmeier via Talk said on Mon, 13 Oct 2025 16:35:07 -0400 (EDT)
From: Steve Litt via Talk <talk@lists.gtalug.org>
It's very much relevant today. If you don't want that UEFI mess, you need to format the boot disk with the old MSDOS partitioning scheme that Carey described almost exactly, so that you can boot to an MBR. Assuming your motherboard allows you to do that.
Not actually: the BIOS doesn't know or care about partitions. UEFI is another matter: it does know about partitions (GPT partitions).
I didn't know I was disputing the preceding sentence. The preceding sentence is good information, but it doesn't negate UEFI's disadvantages.
I was saying that you don't need to format the disk with MBR partitioning (a confusing name) to avoid UEFI. You certainly do need to have a master boot record.
The motherboard, in BIOS / MBR mode, only boots the first 512 byte sector of the boot disk and jumps to it. That requires no knowledge of partitions.
In the preceding two sentences, I think we have an ambiguity about the word "that". Bootloaders like Grub, LILO, etc have no knowledge of partitions, but the 512 byte MBR absolutely does: In fact it contains the partition table in MBR booted computers.
Not accurate. GRUB certainly knows about disk partitions. It even knows how to handle a bunch of file-system types. Very convenient but it means that functionality is duplicated between GRUB and the kernel. I've forgotten what LILO knows, but it amounts to a bunch of disk extents (typically a list of LBAs) that get written into LILO's data by each kernel installation. This kind of breaks file-system abstractions because you cannot move a kernel file the way you can move an ordinary file: LILO will access the old addresses. The first level boot loaders that are often installed as the Master Boot Record usually have an MBR-style partition table embedded in them. This is not mandated by the BIOS "standard". You can put anything in that 512-byte block that can start running in 16-bit Real Mode. You definitely want GPT for any HDD with modern sizes. SSDs are heading that way. GPT is just a Good Thing. It would be easy to write a boot loader for MBR that ends up running grub in a GPT boot disk. Maybe this is already the case with the standard GRUB package. ================== Some systems have used a cut-down Linux kernel as a boot loader. I think that's what "MILO" was on the DEC ALpha. It sounds crazy but it does reduce the chance of problems with re-implemented functionality.