Looking for a comprehensive/"expert" guide to BCD parameters

Posted by Stilez on Super User See other posts from Super User or by Stilez
Published on 2013-10-23T02:28:43Z Indexed on 2013/10/23 3:58 UTC
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I'm interested in educating myself about BCD on Windows 8. There are many, many "walkthrough" guides" and "howtos", but I can't find any guides at typical "enthusiast" level covering what each option or argument in a BCD /ENUM dump might mean, and the principles governing how these all work together.

Imagine trying to rebuild or debug BCD (including EFI/BIOS variants and recovery/hibernate/memtest sections, and perhaps multiple boot Windows/WinPE/WinRE) from scratch using just BCDedit + DiskPart, and trying to understand rather than just copy/pasting commands. That's roughly the knowledge I'm after.

Example questions might be:

  • How is a BCD /ENUM dump to be read, item by item? How do its sections work together? (A lot of guides only show a specific example rather than explaining all the all common args that can exist and what they mean, they don't actually explain how sections work together, or they assume MBR/BIOS/Vista/7 and omit info needed for EFI/GPT/Dynamic disks/8)
  • Partitions are specified by volume letter or as a \Device\HarddiskVolumeNNN. Why does it sometimes show these items as a letter and sometimes as a GUID? What are the practical differences if any?
  • What exactly is syntax like "ramdisk=[C:]\Images\winpe.wim,{ramdiskoptions}" saying, and how will the drive letter "C" be interpreted at runtime in a line like this? Is the drive in such a line always "C:" (most examples assume so) and if not, when wouldn't it be?
  • Many websites state that an sdi device and path may be needed in some sections of BCD, but what is sdi and what are these args doing when they appear?
  • How does the GUID to HDD volume/partition mapping work under EFI/GPT? So that if disks or partitions/volumes change it's clear how one can confirm from basic principles whether data shown in BCD /ENUM ALL is still correct or not.

Does anyone know of a suitable reference source for this kind of raw BCD data and structures? Thanks!

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