What, exactly, does setting the boot partition to BOOT do?

Harry37

Member
EasyBCD is incredibly useful. But there's one thing I can't seem to find in the documentation. On the Advanced Settings page, you can set the "Drive" to "BOOT". I assume this means the boot partition set in your BIOS or overridden in the BIOS. But is that correct? Is there any reason I shouldn't set all of my various BCDs for all of my boot partitions to "BOOT"?

Thanks!
 
Your understanding of what BOOT means is correct, but I'm not sure you realize the implications. The boot files are only physically present on a particular partition, specifying BOOT means that the bootloader may look for the files on the drive the BIOS was configured to boot from and then not find them if it differs from where they're actually stored.
 
No EasyBCD merely gives you more control over Windows boot menu, in whatever partition you've installed EasyBCD on.
 
Your understanding of what BOOT means is correct, but I'm not sure you realize the implications. The boot files are only physically present on a particular partition, specifying BOOT means that the bootloader may look for the files on the drive the BIOS was configured to boot from and then not find them if it differs from where they're actually stored.
Thank you, @mqudsi for your helpful reply. Please allow me to rephrase that to see if I understand correctly. All of my Windows bootable drives/partitions contain an MBR (I dislike UEFI; all my boot disks are 500 GB or less), and all the other files necessary to boot Windows 10. And they are all marked "Active". Since that is the case, is my understanding summarized in my OP correct?

The reason I would like to use that feature -- if I'm right -- is when I run EasyBCD and load another partition's BCD store to make changes. I'm just a little leery of specifying drive letter "C:" as the boot drive because, while it will be assigned that letter during boot, that letter is assigned to the current boot partition rather than the target system. I'm sure I'm worried over nothing in a strictly technical sense; it's just that it makes me more comfortable to specify "BOOT" in such a case rather than "C:", even if it all ends up with the same behavior.

Given that scenario, will it cause any problems if I specify "BOOT" whenever I alter a bootable partition that's not currently running?

No EasyBCD merely gives you more control over Windows boot menu, in whatever partition you've installed EasyBCD on.
Dear @Ex_Brit, I'm afraid that your reply confused me. Does it really matter what partition contains EasyBCD if I select some other partition's BCD store? I assumed that the only thing unique to the EasyBCD installation partition is that it defaults to the currently booted system's BCD store. Is that incorrect?
 
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Thank you, @mqudsi for your helpful reply. Please allow me to rephrase that to see if I understand correctly. All of my Windows bootable drives/partitions contain an MBR (I dislike UEFI; all my boot disks are 500 GB or less), and all the other files necessary to boot Windows 10. And they are all marked "Active". Since that is the case, is my understanding summarized in my OP correct?

The reason I would like to use that feature -- if I'm right -- is when I run EasyBCD and load another partition's BCD store to make changes. I'm just a little leery of specifying drive letter "C:" as the boot drive because, while it will be assigned that letter during boot, that letter is assigned to the current boot partition rather than the target system. I'm sure I'm worried over nothing in a strictly technical sense; it's just that it makes me more comfortable to specify "BOOT" in such a case rather than "C:", even if it all ends up with the same behavior.

Given that scenario, will it cause any problems if I specify "BOOT" whenever I alter a bootable partition that's not currently running?


Dear @Ex_Brit, I'm afraid that your reply confused me. Does it really matter what partition contains EasyBCD if I select some other partition's BCD store? I assumed that the only thing unique to the EasyBCD installation partition is that it defaults to the currently booted system's BCD store. Is that incorrect?
You are correct
 
There are no device letters in the BCD.
EasyBCD is translating the user unfriendly UID into a letter for you, and vice versa depending on whether you're reading or writing to the BCD. It does this by looking up the letter in the registry device map of the running system.
Make sure that you specify a letter for the device as it's seen by the currently running system, no matter which BCD you're working on, regardless of what you think the letter will be when a different system is booted.
Because the letter is not actually present in the BCD, when you boot the system of the BCD you're working on, that system will report the letter as mapped in its registry, regardless of what it was when the original system was running.
Nothing in the BCD has changed, it's just that each Windows OS has it's own unique registry map and EasyBCD reflects that for you.
 
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