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aljones15 01-01-2012 08:29 AM

Using Grub for BCD commands in Win7
Hey Folks,

Have a dual boot desktop with gentoo and windows.
I have a small problem, in windows I am running a number of games and need to allocate virtual memory to them. In order to do this I have to use bcdedit, but I believe that because I am using grub there are no bcd files in my windows installation. I get the error file not found when I try. Is there a way to do this with grub?

this is the command that I need to execute
C:\ bcdedit /set increaseuserva 2500

Is there a way to tell grub to pass this to windows on boot?
BTW am I correct that grub replaces bcd on a dual boot system?

paulsm4 01-01-2012 12:32 PM

Hi -

You're correct - there is only *one* "Master Boot Record".

Typically, you install Windows Vista/Win7 first, install Linux afterward, and allow Grub(2) to select Windows or Linux at boot time. Grub replaces the Vista bootloader, but "everything works". This is exactly how I have all my dual-boot systems configured (I've have XP, Vista, Server 2008, Win7, Grub and Grub2).

*However* - I've never needed to fiddle with bcdedit on a dual boot system.

Here are links that allows *both* Grub2 and the Win7 bootloader to *coexist* (each on a different partition):

jefro 01-01-2012 01:04 PM

Chain load from grub to bcd.

paulsm4 01-01-2012 03:20 PM

Hi -

Actually, this is probably the easiest solution: just run bcedit from Windows.


EXAMPLE: c:\windows\system32\bcdedit /set increaseuserva 2500  c:\boot\BCD
Look here:

1. "BCD" is the boot database, stored in XXX:\boot\BCD (where "XXX:" is your boot drive)

2. This is true regardless of whether you're booting via grub or BCD. The BCD file is there for any viable Vista/Server 2008/Win7 install.

3. "Bcedit" the BCD database, and you've set your configuration.

Voila. It should really be as easy as that!

'Hope that helps!

aljones15 01-01-2012 08:15 PM

It's not that easy win7 says I have nothing to bcdedit.

jefro 01-02-2012 10:26 AM

Cause grub overwrote the bcd?

aljones15 01-02-2012 08:29 PM

Yeah not sure if that's what happened, but I did have to reinstall grub after installing windows hence there does seem to be a conflict between the two.

syg00 01-02-2012 11:22 PM

This isn't making a lot (any) sense. The BCD is in the NTFS filesystem. Nothing to do with grub - unless you happened to (incorrectly) install grub into that partition. In which case Win7 wouldn't boot at all, so it appears you didn't do that.
You need to be admin to run bcdedit - try it from the install DVD (recovery centre).

I get the error file not found when I try.
Let's see the (entire) message.

jefro 01-03-2012 09:06 PM

Might use easybcd to fix it.

See down the page to linux.

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