I have a laptop that has Windows 7 64 bit Enterprise edition. It is already filled with plenty of Software and drivers.
The laptop (Dell E6220) supports booting through UEFI, but the insatllition was on legacy BIOS.
When I try to change the booting from Legacy to UEFI I get an error message that no boot device was found (the Windows 7 doesn't recognize as bootable). Is there any way I can configure the current install to allow booting from UEFI or do I have to format and reinstall?
No, you shouldn't have to format and reinstall, as you can convert your disk to allow UEFI booting via gptgen, an excellent opensource project that non-destructively converts a MBR partition table to GPT.
Microsoft published a good tutorial on this process (unabridged), with the abridged version below taking <10 minutes to do:
Disk 0)gptgen, start a cmd prompt as Admin, and run: gptgen.exe -w \\.\physicaldrive0
diskpart, identifying the boot disk containing Windows via list disk:
Disk ### Status Size Free Dyn Gpt
-------- ------------- ------- ------- --- ---
* Disk 0 Online 128 GB 0 B *
select disk <#> and verify via list partition:
Partition ### Type Size Offset
------------- ---------------- ------- -------
Partition 1 Primary 350 MB 1024 KB
Partition 2 Primary 126 GB 350 MB
select partition 1
delete partition
create partition EFI size=100 offset=1
format quick fs=fat32 label="System"
assign letter=S
create partition msr size=128 offset=103424
list partition:
Partition ### Type Size Offset
------------- ---------------- ------- -------
Partition 1 System 100 MB 1024 KB
Partition 2 Reserved 128 MB 101 MB
Partition 3 Primary 126 GB 229 MB
3 with the Windows installation, then exit:
list volume
select volume 3
assign letter=C
exit
C: with the Windows installation, then reboot:
bcdboot C:\Windows /s S: /f UEFI
Convert Windows Installation from Legacy to UEFI:
Please note that this technique will work only for those computer systems which support UEFI firmware. Please check that first in your BIOS settings and then continue with this tutorial.
Step 1:
Confirm that you installation is indeed in Legacy Mode. Press WinKey + R and then type msinfo32 and hit enter.
The BIOS mode should be Legacy in System Summary.
Step 2: Download System Rescue Disk and make a bootable media from it. Download the disk from here. See instructions to make bootable media. That is pretty trivial and one can follow this tutorial.
testdisk
Use the arrow keys to navigate.
Select your HDD in which Windows is installed in Legacy Mode and press enter.
Select [EFI GPT] EFI GPT Partition Map and press enter.
Select Analyze and hit enter.
Select Quick Search (at the bottom) and hit enter.
Select Continue (at the bottom) and hit enter.
Hit enter again.
Select Write (at the bottom) and hit enter.
Press Y and hit enter.
Your partition table has changed from MBR to GPT.Step 7: Run the following commands:
diskpartlist disk - Note the disk number which contains your windows installation. Let us say, it is xselect disk xlist partition - Note the partition number which contains your windows installation. Let us say, it is yselect partition yshrink minimum=200 desired=200create partition efilist partition - Note the partition number of the new one. Let us say, it is zselect partition zformat fs = fat32assign letter = b:exitmkdir b:\EFImkdir b:\EFI\Microsoftcd /d b:\EFI\Microsoftbootrec /fixbootdiskpartlist volbcdboot c:\windows /l en-us /s b: /f ALL - Please note that here c: denotes the letter of the partition in which windows is installed. Lets find that out first.Step 8: Reboot. Tada! Done! Check whether your installation has changed into UEFI or not.
Ref: How to Convert Windows 7/8/8.1 Installation from Legacy to UEFI Without Data Loss!
Simpler way using gdisk: Convert Windows 7/8/10 Installation from Legacy to UEFI Without Data Loss (Simpler Method)
Windows 7 on UEFI requires that the disk partitions use GUID partition table (GPT) rather than the traditional MBR partitioning format found on BIOS systems. Unfortunately, windows provides no way of converting an MBR partition to a GPT one non-destructively.
However, if you don't mind copying data off your drive, converting, then copying it back then you could use Windows to do it as described in this Microsoft Technet article Change a Master Boot Record Disk into a GUID Partition Table Disk. The article describes two procedures, both of which require making a copy of the data then modifying the disk to use GPT. Using the Windows interface you first delete any volumes on the disk and then convert the disk to a GPT disk using right click on the disk and selecting menu items. Using the command shell with Admin elevation, you use the diskpart utility to delete any volumes and then convert the disk to a GPT disk.
If you don't want to backup the data first and have access to a a Linux machine that you can install the drive in, there are tools in Linux that will allow you to convert the partition type non-destructively as described here. If you don't have a Linux box handy, you can also try creating a Linux boot CD and booting from that.
Searhing for "convert MBR to GPT" brings up other tools, but I have never tried them.
A quick addendum to nathanbedford's answer:
As simonzack said, Windows 7's bcdboot doesn't support the /f flag.
I didn't have any problems; just had to run bootrec /rebuildbcd
immediately after running Nathan's commands and it worked a treat.
The second, 128 MB partition is not necessary. I had no room, and just ignored it. Everything's working fine so far.
I did what @nathanbedford said, however Windows 7 bcdboot doesn't accept /f flag so in order to finish the last step
bcdboot c:\windows /s s: /f UEFI
you need to use a newer version of bcd, that's >=win8.
Two different ways to do this are, either copying a newer bcdboot.exe into an readable drive so you can access it from cmd (that's how I did it), or running a newer Windows system repair disk.
Let's say the Windows 7 install that we want to process is on HDD1.
I have been able to do it with @nathanbedford's method with a few modifications:
no use at all of a system repair disc / original Windows installation media
boot on a secondary Windows 10 install (e.g. on HDD2)
similar use of gptgen.exe -w \\.\physicaldrive0 from a cmd.exe run in administrator mode (it did not work from Powershell in my test, but it worked from cmd.exe admin)
the rest is nearly identical, except Step 13 for which the second reserved partition create partition msr size=128 ... was not needed for me
since I booted on HDD2 (Win 10), HDD1's C:\ is now called D:\, and I had to modify it like this:
bcdboot d:\windows /s s: /f UEFI
(thus using Win10's bcdboot; I thought it would fail because it would create a Win10 boot system, but in fact it worked, see also @xkazuko's answer here)
reboot on HDD1, Windows 7 is now in UEFI mode
PS: after all these steps there will probably be two entries named "Windows Boot Manager" in bcdedit /enum firmware. Then you can do:
bcdedit /set {bootmgr} description "Windows 7"
bcdedit /set {...} description "Windows 10" (or even /delete if the other entry is not needed)
An easy method is using a third-party product in the following two steps:
The can be done in this way:
Download the AOMEI Partition Assistant Professional Edition Demo and run it
Right-click on the system disk and select "Convert to GPT Disk"
Click "Apply" to apply the change
During the process, the computer will reboot into AOMEI Pre-OS mode.
When it completes, go into the BIOS and switch the boot mode from Legacy to UEFI mode.
I suggest taking a complete image backup of the disk before starting, where the free AOMEI Backupper Freeware can again be useful.
For more information see the article How to Change Legacy to UEFI in Windows 10/8/7.
