On Wed, Oct 30, 2024 at 06:40:02PM -0400, D. Hugh Redelmeier via talk wrote:
Not really. Everything starts small, but Linux was quite large by the time it was really useful for something other than Linux development.
As far as I know, every machine that has UEFI implements MBR booting through UEFI. In particular, the "CSM" implements BIOS calls.
CSM is gone on newer machines.
I don't think that you are avoiding vulnerabilities using MBR on a machine with UEFI.
MBR's primary partitions are actually described by a few entries in the last bytes of the boot sector. There is only room for four entries so the additionally hack of "extended partition" was invented.
Where does you boot loader live in MBR? The primary boot-loader loads a secondary boot-loader from the partition to be booted. Where does the secondary boot loader (which must fit in a single block!) get the rest of the machinery for booting? Normally from an list of absolute block numbers (very fragile).
UEFI has a less hacky answer: the ESP is a full fledged file-system allowing files to be used.
These hacks can mean perplexing behaviour unless you understand how it is all put together.
Secure Boot, which comes with UEFI, is a little bit of a comfort. Not perfect.
Yeah for most things UEFI is a better design. They did have a lot of years to think about how to fix the mess of the MBR boot process. -- Len Sorensen