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Author Topic: How big is your ESP partition?  (Read 251 times)

Offline PDP-8

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How big is your ESP partition?
« on: January 04, 2022, 02:22:35 PM »
For those of us who like to build our own 64-bit EFI systems from the distribution files ...

I was always told to "just make it 100mb" or so.  Seemed pretty random, until I found this explanation on how it differs if you are using FAT16 or FAT32 etc.

https://www.ctrl.blog/entry/esp-size-guide.html

There is so much conflicting / guesswork out there, that at least this seemed to be some sort of guide.

Does your ESP partition *have* to be the first one, or can it exist elsewhere?  Seems it depends ultimately on what you want to do, although some claim that it has to be the first one.  However, the last statement by Rod of Rod's books makes it clear that for the most part, it doesn't.  Everything seems to hinge around what must-or-should really means.

https://askubuntu.com/questions/618244/does-the-uefi-partition-either-must-or-should-be-first-for-some-reason-if-s

Good info.  At least it is something to consider when building up TC64 for yourself.

Also, even if you don't intend to use a normal FAT filesystem for your stick and are only going to use non-fat filesystems for system use, Grub itself needs the fat module, so don't rip that out!  This I haven't tested yet as I'm not a grub-master.  Yet. :)


« Last Edit: January 04, 2022, 02:54:31 PM by PDP-8 »
That's a UNIX book! - cool  -- Garth

Offline nick65go

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Re: How big is your ESP partition?
« Reply #1 on: January 05, 2022, 07:56:49 AM »
I said few times on this TC forum, but maybe I must repeat it again:

- ESP partition is for any UEFI (be it UEFI32 or UEFI64).
- ESP partition can be on a MBR or on GPT disk.
- ESP maximum size can be as all HDD/SDD - but not very useful.
- ESP partition can be at any position on HDD, be it first, last, the 69-th, whatever.
- There can be multiple ESP partition on the same HDD !! I have 4 ESP on my HDD :)
- ESP minimum size can be less than 500 KB; JUST to contain the boot-loader (mini-grub preferably) and (optionally) its (few bytes) configuration. Then you can chain-load whatever kernel/loader.
- ESP format(FAT12/16/32) does not matter, as long as the firmware knows it. [Some UEFI firmware natively understand NTFS or exFAT file-systems for ESP].

But for novice users, and greater compatibility to many devices/laptops, you can use GPT type USB/disk, FAT32 format, ESP is 1-st partition on disk, etc. If ESP already exist on disk (because Micro$oft win10) use it as it is.

Oh, and full-grub (modules embedded) can be less than 1MB. The fonts do not need to be 2.5 MB, you can use an ASCII font of few KB, etc. I do not waste time admiring grub screen styles/photos, my grub purpose is to fast load the desired kernel.

PS: I like to share info/knowledge; but usually I test it (real/ virtual) before spreading other's (not-tested) info.
« Last Edit: January 05, 2022, 08:04:04 AM by nick65go »

Offline polikuo

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Re: How big is your ESP partition?
« Reply #2 on: January 14, 2022, 01:34:14 AM »
Mine is around 150 MB as I have several versions of TC including my home-brew ones.
They add up to just around 100MB, it really depends on you need.

Offline PDP-8

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Re: How big is your ESP partition?
« Reply #3 on: January 14, 2022, 06:02:31 PM »
Great info guys.

What I'm thinking is that perhaps to help ensure 64-bit UEFI compatability with the most amount of machines, older and modern,  that the EFI partition should be larger Fat32, and not a small FAT16.

And no, manufacturers aren't regularly cruising our threads to change their ways to our small-at-all costs mindset. :)

From my perspective as TC being a *nomadic* tool I can take from any machine I present it to in my travels, perhaps a larger EFI which mkfs will recognize and default to using FAT32 makes sense.

Just in case some uefi hardware has trouble recognizing a FAT16 partition, making it a more practical solution, rather than a radical rant at the manufacturers. :)


That's a UNIX book! - cool  -- Garth