SlyGuy SlyGuy - 8 months ago 39
Bash Question

What is the difference between FS0 and BLK0 in UEFI shell mappings?

I think FS stands for filesystem, but I don't know what BLK stands for. Not only that, but what are the meanings behind the pci hierarchy parameters. i.e. When I see HD(1,MBR,0x0003B) what does "1","MBR", and what looks to be an address, stand for?

Here's the mapping table I'm looking at in UEFI shell:

Mapping table
FS0: Alias(s):HD21a0e0b:;BLK1:
FS1: Alias(s):HD23a0a1:;BLK4:
BLK3: Alias(s):
BLK0: Alias(s):
BLK2: Alias(s):

I'm guessing BLK's are available ports and FS's are physical things that are plugged into those ports. It looks like once somethign is plugged into a BLK, it becomes an FS, but still retains its BLK value. i.g. FS0=BLK1


According to archwiki:

  • fsX means filesystem
  • blkX means block device or data storage device

MBR should mean Master Boot Record

HD should mean Hard Drive

1 might mean Primary, 2 Secondary Partition

That hex number after MBR could be the device signature or disk identifier. Or maybe an offset of that device to important information.

Links that might help further: