Dual boot efi/System Reserved partition size

gbn15

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On Windows 10 installation, it creates an EFI system partition as required by UEFI & a System Reserved partition in Bios.MBR mode. This partition's capacity is 100 megabytes. The recommended EFI system partition for Linux is 260-512 megabytes of capacity . Dual booting is for both operating systems to boot from the same EFI partition.
In a dual boot configuration do i need to resize either the Efi partition or System Reserved partition to 512MiB?
 


something your saying doesn't add up. With a UEFI PC where firmware is UEFI boot files will be stored on the EFI partition ; but my understanding is you can't have both. In fact with UEFi there's usually a protective section.

Anyway, lets cut to the chase with a lot of OS's on a disk an EFI of 100mb's might be tight ,but for just 2 OS's windows and Linux that should be OK.

So basically if you were to install linux onto a HD that has Windows, run defrag from the running Windows to clean up data. The section you can install Windows would be after the EFI and any Windows backup stuff, if there is enough room. IN other words how big is your HD or SSD and how much of that is taken up by windows? if you can boot from a Linix OS on a usb stick, fire gPArted and then take a screen shot that would tell us. Anyway assuming you make room, install Linux , then what happens is that when it comes to installing the boot loader ,linux will store some files onto the EFI partition , Windows files will still be there on the EFI . After grub is installed , you update grub and this should recognise the Windows install, so bascially on a cold boot you should get the choice to boot either Windows or Linux .Bascially the EFI partition will be "shared" . boot files for the UEFI system will have file from both Windows and Linux. You can use some software and run from command that will show entries. i've only got Arch but if I run that command this is what it shows :

Code:
[andrew@darkstar:~]$ sudo efibootmgr -v                                   (03-25 20:20)
BootCurrent: 0000
Timeout: 0 seconds
BootOrder: 0000,0001,9999
Boot0000* boot	HD(1,GPT,192a9aa1-9848-4329-8171-9253ffc0f920,0x800,0x32000)/File(\EFI\boot\grubx64.efi)

With the successful install of a few OS's on a UEFiI system there wil be a few entries

if you look at attached ,you will see my lean Arch system, since i don't have a lot of room.Note my EFI is only 100mb
 

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Captain sensible thanks for the explanation.I was really getting confused about that minimum requirement of 260MB for ESP in Linux & also I had seen images of partition table posted by others showing the Efi partition to be in the 260 to 550MB range.
So i guess for dual booting in BIOS/MBR disk.,100MB of System reserve is sufficient.

If i may ask another question:
In single boot Hard Disk where Linux is the sole OS,when installing latest version of Linux Mint & selecting Something Else to do manual partitioning,is it still necessary to create boot partitions? /boot partition in BIOS /MBR disk
/boot/efi partition in UEFI/GPT disk
 
/boot is different from /biosboot and /boot/efi
If it was me, I would re-create it, or at the least reformat it.
Just to clear out any old un-necessary stuff that might be conflicting.

The original efi spec was for 200 Meg. It may have changed since then.
I would think 100MB would be plenty, unless you've installed a dozen OS'es.
 
My EFI partition is 105 MB and is 38% used dual booting windows 10 and ubuntu. So the two of them are using roughly 38 MB.

--glenn
 

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