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I'm having issues with BCD on Windows 8. 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, and BCD is a very long-standing tool, so I'm asking for help on my specific issues here:
- 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.
- Is there any guide on the web, how a BCD /ENUM dump is to be read, item by item, so I can debug it myself? 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)
There are many, many "walkthrough" guides" and "howtos", but 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 which would help with my questions, but if it exists I can't find it. So ideally, does anyone know of a suitable reference source for this kind of raw BCD data and structures? If not, then at least can my specific questions be helped.
Thanks!
Stilez
Posted 2013-10-23T02:28:43.023
Reputation: 1 183
This is seriously useful stuff. Mods, please allow it to be open in some form. bcdedit has been there for the past 4 windows editions and will probably continue to be there for a while now. It is a system administration tool, which is exactly the scope of superuser.com – Milind R – 2013-10-29T14:20:12.157
Besides, and more importantly, I haven't been able to find a reference of this sort despite scouring the net for it. Not even on TechNet. – Milind R – 2013-10-29T14:27:57.190
The specific questions are on topic. It seems silly to ask such core questions and not ask if a guide covering the area generally exists, but I can do that if needed. As Milind says, BCD is a crucial systems tool with no good information source. – Stilez – 2013-10-29T18:46:21.750
Questions looking for off-site resources are considered off topic, not only because they link to resources that may go offline anytime (rendering existing answers useless), but also because we'd just get a collection of links as answers. Rather ask the question you need the answer to, focusing on a specific problem. Your question right now is too broad, but each of your bullet points could be considered several questions that can easily stand on their own and attract a good answer. – slhck – 2013-10-29T18:54:52.847
I've had a go at rewording it to emphasise the issues that actually raised the question. Hopefully it's moot and we can look for answers now? :) – Stilez – 2013-10-29T19:33:02.467
Slhck, so you say he shouldn't have asked for links? On one hand, the questions are supposed to be general enough to be useful to others. On the other hand, there's this extremely frustrating label of "not a real question", which seems to be another way of saying that fixing/achieving something is the focus, never is actual understanding. And hacks/fixes/tutorials don't need all this stackexchange goodness. – Milind R – 2013-10-29T19:47:26.463
(Both, please reply with
@slhck, otherwise I won't get a notification. I just saw this by accident.) As I mentioned, the question is too broad. For a question to be useful, it should be as specific as possible to a certain issue, not asking five (rather) unrelated questions. Each of your bullet points could be an individual question. Just don't ask for a tutorial, ask for the actual issue you're having. If someone links to a tutorial and explains the important parts here, so be it. – slhck – 2013-10-29T19:49:03.617OK @Slhck so the question, without any dressing, is "can someone specify in detail what the command line switches and options of
bcdeditare, and what they can be used for?". Would that be a valid question? Yes it's too broad, but since there isn't a complete reference anywhere yet, what's wrong with it? Or rather, what can be done about it? Should I ask about each command line switch separately? Isn't that a little dogmatic? – Milind R – 2013-10-30T06:30:21.943I'd consider that too broad as well. It could be answered by just looking at the documentation. Please note that Super User is not supposed be the replacement for official documentation or a home for complete references. The Q&A format is just not suited for that. If you ask about a specific problem you're facing or a thing you need explained here, on site, you're likely to get a better answer, which is the main point I'm trying to make. For further discussion about how to improve this question, head to [meta], please.
– slhck – 2013-10-30T07:07:39.497