Bug 2467673

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anaconda.log

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anaconda-webui.log

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dbus.log

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journal.log

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packaging.log

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program.log

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storage.log

Currently indeed anaconda when it detects an existing ESP on the dual boot scenario, it tries to reuse it, no matter the size. https://github.com/rhinstaller/anaconda/blob/2ed79f7cadde4bc5a93998a29e4a1442e76e2472/pyanaconda/modules/storage/partitioning/automatic/utils.py#L347

Related to the anaconda's size requirement for the ESP for 500MB here is the Fedora change: https://fedoraproject.org/wiki/Changes/BiggerESP 

About the suggestion to not share the ESP with windows, rather create a new one, I take the proposal, we need to investigate the implications before going forward.

(In reply to Katerina Koukiou from comment #8)
> Related to the anaconda's size requirement for the ESP for 500MB here is the
> Fedora change: https://fedoraproject.org/wiki/Changes/BiggerESP 

Thanks, this is very useful. It says:

> Windows 10 and 11 allocates an ESP of at least 500MiB.

Which is not true at least in my case (latest Thinkpads preinstalled from Lenovo). It is 450 MiB instead.

Maybe the number can vary according to circumstances? Or Microsoft changed it recently? If needed, I can do some experiments with a completely fresh user install, if that changes anything.


> About the suggestion to not share the ESP with windows, rather create a new
> one, I take the proposal, we need to investigate the implications before
> going forward.

Thanks. In my personal opinion, it would make sense to just reuse the existing ESP, and not warn about it. E.g. disable the warning if installing into dual-boot AND the ESP >=400 MiB (or 450MiB, the logs should tell you an exact number). Because it does satisfy the spirit of the proposal (speaks about sharing ESP with modern Windows), even though not the exact size number (which might be a mistake in the proposal itself). 

Creating the ESP from scratch would still create 500 MiB partition, just the warning would be adjusted in this dual-boot case.

Also, talking to Richard might be helpful.

@Richard, it seems that more Windows systems than expected in the Change https://fedoraproject.org/wiki/Changes/BiggerESP have the ESP size lower than 500M.

Could you provide some input:

1) Can we lower the recommended size to 400? What would be the impact?

2) Does a user need to care how much *free space* is left, when adding a new system, or is it more about the *total size* of the partition?

3) What you would recommend to a less experienced user with 400M ESP size willing to install a dual boot system - to proceed with the installation or to repartition the system?

4*) Do you know some Lenovo folks who can clarify what was the decision regarding pre-installed laptops they setup and what are their plans going further? If the size they setup comes from some documented heuristics, maybe we should rely on a similar one?

> Can we lower the recommended size to 400? What would be the impact?

We could; although the everything in the BiggerESP page is still true. It's most possible that Lenovo changed the Windows default on their preload -- it would be interesting to wipe the exact same machine and do a fresh install of win11 and see what it picks without the Lenovo preload getting involved.

> Do you know some Lenovo folks who can clarify what was the decision regarding pre-installed laptops they setup

I certainly could find out; I did think 500MiB was part of the WHQL cert these days so I'm a bit surprised it's not at least that.

I can provide some updated numbers after my experiments today.

Lenovo-preinstalled disk layout:

$ lsblk -o NAME,SIZE,FSTYPE,FSVER,LABEL,PARTLABEL /dev/nvme0n1
NAME          SIZE FSTYPE    FSVER LABEL                        PARTLABEL
nvme0n1     953.9G                                              
├─nvme0n1p1   450M vfat      FAT32 SYSTEM                       EFI System Partition
├─nvme0n1p2    16M                                              Microsoft reserved partition
├─nvme0n1p3 951.4G BitLocker 2     X1CARBONG14 Windows 5/7/2026 Basic data partition
└─nvme0n1p4     2G ntfs            WinRE_DRV                    Basic data partition

A clean Windows 11 25H2 installation disk layout:

$ lsblk -o NAME,SIZE,FSTYPE,FSVER,LABEL,PARTLABEL /dev/nvme0n1
NAME          SIZE FSTYPE    FSVER LABEL                    PARTLABEL
nvme0n1     953.9G                                          
├─nvme0n1p1   200M vfat      FAT32                          Basic data partition
├─nvme0n1p2    16M                                          Microsoft reserved partition
├─nvme0n1p3 952.9G BitLocker 2     X1CARBONG14 C: 5/12/2026 Basic data partition
└─nvme0n1p4   735M ntfs                                     

When I reported this bug, I assumed that the Lenovo-preinstalled layout is the same as the default Windows layout. Unfortunately, Win11 (25H2) still defaults to a 200 MiB ESP :-(

That is even documented here:
https://learn.microsoft.com/en-us/windows-hardware/manufacture/desktop/configure-uefigpt-based-hard-drive-partitions?view=windows-11#system-partition

My chatbot claims that many vendors enlarge the ESP to store their pre-boot diagnostic tools, boot logos, etc. No idea whether it's true.

Since I learned that 450 MiB is not a Windows default, but just a Lenovo default (and other vendors probably have a different default size), I guess the best course of action here would be to define the "minimum acceptable ESP size for dual boot" value (because for dual boot, the user most likely can't easily change the partition size). If ESP is smaller than that, either show a very clear warning message (including consequences, e.g. "you might not be able to update firmware in the future") or create a second ESP just for Fedora right away. If ESP is larger than that, but still smaller than the default 500MiB value, show a more reassuring warning message (e.g. "Your ESP is 450MiB instead of the minimum recommended 500MiB, and we recommend you to make it larger. But if you can't easily change the partition size, e.g. because of a dual-boot OS, this size should still work sufficiently well.").

If you want to go this route, the question, of course, is, what this "minimum acceptable ESP size for dual boot" size should be...