[Solved] mounting efi partition on /boot/efi

[juniper]

I am installing gentoo right now.

I have a windows partition on the machine. There is already an efi partition so I don't think I should follow the guide and create a new efi partition.

I installed gentoo a few months ago on another machine (the machine I am currently typing from, so it works). and I thought the recommendation was to mount the efi partition on /boot/efi but now the recommendation seems to be to mount the efi partition on /boot.

is this correct? Can I do it the old way that I know works.

[Banana]

I'm also somtimes confused about the mount paths. So no answer here.

But you should use for each OS its own EFI partition. This way the other OS does not overwrite anything.

[NeddySeagoon]

juniper,

It all depends how you will choose which operating system to boot.

With separate EFI partitions, you will have separate boot loaders for each.
Each will have its own EFI compliant binary to be loaded by the firmware.
To choose operating systems, you would normally enter the firmware and change the boot order or set the boot override.

However some boot loaders can 'chain load' other boot loaders, so you could use one boot loader to load other boot loaders.

Alternately, you choose at the outset to have one boot loader. The firmware always starts this boot loader, so there is no faffing about in the firmware settings.
All the various operating systems appear on the boot loaders menu.

There is no restriction on where kernels and initrd files go, unless your selected boot loader places some restrictions.

All three ways are right, pick one.

[Goverp]

... you should use for each OS its own EFI partition. This way the other OS does not overwrite anything.

I'm not sure I understand this. AFAIK there is only one EFI partition on a disk, and it's the way an UEFI-booting pc finds its boot manager; there's a flag in the GPT partition table to identify it. If you created multiple partitions to do EFI things, you'd have to fiddle around in BIOS to switch from one to another.

OS's in general do not write to the EFI; their installation process might if you let it, or if it's badly written, but you should always take care when installing any OS (for example, when partitioning ). I've had Windows make a mess of the Windows entries, but not my Gentoo ones!

I'd guess the most common area you might expect a conflict is trying to install Windows alongside Linux, but Windows puts its own bootloader into EFI/Windows, whereas say Gentoo uses, not surprisingly, EFI/gentoo, and should not play outside those directories. Some bootloaders can do more complex stuff - rEFInd uses EFI/refind like it should; Gentoo's GRUB puts grub64.efi into EFI/gentoo, but in this case you can legitimately argue GRUB is part of Gentoo. Things will get more complex if you install another Linux alongside - say Ubuntu. I don't know, but perhaps Ubuntu might create another grub64.efi somewhere, but that's irrelevant - you'd still use the same GRUB instance and need to update its /boot/grub/grub.cfg, which of course is not in EFI at all!

I agree this area contains traps ready to catch the unwary, but I don't think separate EFI partitions is a solution.

[pietinger]

Can I do it the old way that I know works.

YES !

You can mount your (existent) ESP (efi system partition) to any directory you like ... just give the installation routine of grub the correct info about this directory. UEFI specification says: This ESP must have a directory named "efi" (or "EFI"). In this directory you can have multiple directories (*) with bootable binaries (must have .efi as suffix). There are more than two possible solutions:

1. Our AMD64 handbook recommends to use the directory /boot as mount point for this ESP. So you will have /boot/efi ... and all grub files will go into your ESP (needs one mount to access \efi).
2a. You can have an extra partition for/as your /boot. Then you must mount this partition to /boot ... and all grub files will go into this extra partition. In there you will need a directory for mounting your ESP. Mostly it is named also "efi" - but you could also name it "esp"; then you will have /boot/efi/efi or /boot/esp/efi (needs two mounts to access \efi)
2b. You can use the existant boot-directory of your root partition without mounting an extra partition to it ... and all grub files will go into your root partition. In there you will need a directory for mounting your ESP. Mostly it is named also "efi" - but you could also name it "esp"; then you will have /boot/efi/efi or /boot/esp/efi (needs one mount to access \efi)


(* here are mine:

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# efibootmgr
BootCurrent: 0002
Timeout: 1 seconds
BootOrder: 0002,0000,0001
Boot0000* Secure        HD(1,GPT,0adcbfee-21aa-42ea-9a9a-2e53bd05e6a2,0x800,0x7f800)/File(\efi\secure\bzImage.efi)
Boot0001* gentoo        HD(1,GPT,0adcbfee-21aa-42ea-9a9a-2e53bd05e6a2,0x800,0x7f800)/File(\EFI\gentoo\grubx64.efi)
Boot0002* Unlocked      HD(1,GPT,0adcbfee-21aa-42ea-9a9a-2e53bd05e6a2,0x800,0x7f800)/File(\efi\unlocked\bzImage.efi)

[juniper]

@Banana: I think you are wrong. But someone here knows better than me and they can set things straight.

@the rest: Thanks for the replies. Neddy, I like my /boot/efi partition used along with GRUB. I think I am going to that route, which I think is endorsed by pietinger.

[Banana]

The multiple efi or esp partitions topic is not really 100% clear https://news.ycombinator.com/item?id=16261237
But there are cases in which https://devblog.xkern.net/multiple-efi- ... ingle-disk , https://forum.manjaro.org/t/create-a-se ... ot/62066/9 , https://forums.opensuse.org/t/why-multi ... t/143881/6 they do work.

[juniper]

@Banana: weird. Never seen multiple esp partitions.

@pietinger: it always seemed weird to me to have the esp partition mounted on boot in a dual boot machine.

In any case, for anyone reading this, my setup is (not quite, I have nvme partitions) but for simplicity

/dev/sda1 esp partition mounted on /boot/efi
/dev/sda2 mounted on /boot
/dev/sda3 mounted on /

Then when you get to the configuring bootloader section of the install manual, install grub as instructed. Now mount all of the partitions above (likely, you already have / and /boot mounted, so you only need to mount /boot/efi). Unless you need to do something funny, this is basically the only time you ever need to mount /boot/efi (in my fstab, I have /boot/efi set to noauto, so it does not mount on boot). After you build your kernel, installing it puts your kernel in /boot. Then execute

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grub-install --target=x86_64-efi --efi-directory=/boot/efi

This is the key line and where you can basically mount your esp partition anywhere (replace the last argument with wherever you mount it). Then

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grub-mkconfig -o /boot/grub/grub.cfg

After this you should be good to go. On my desktop I never mounted the /boot/efi drive after this. All updated kernels just go in /boot and the grub-mkconfig command above updates the grub menu. The esp drive isn't touched.

[Banana]

I'm running currently a dual boot with windows. (Multiple PCs and this one I was not sure about. So I needed to check it first)

There are two disks (physical) which do have their own EFI partition.

[pietinger]

@pietinger: it always seemed weird to me to have the esp partition mounted on boot in a dual boot machine.

Everything has its advantages and disadvantages ... yes, it depends also what you want to do.

For example: I dont use grub anymore (only as backup); I have my two (stub-) kernels (with different configs) and boot them directly from UEFI; this means I dont do a "make install" because I must copy my kernels into \efi\...\bzImage.efi. So, it is more senseful (for me) to mount my ESP directly to /boot (and of course I am an old man I have a "noauto" in my fstab for this) and DONT need two mounts (and dont need the ugly ".../efi/efi/...")

For dual booting with windows your approach could fit better for you.

(wwe had a time with a lot of confusion because our AMD64 handbook recommends to mount ESP directly to /boot, while in our Wiki article your solution with an extra partition for boot was described)

[GDH-gentoo]

There are two disks (physical) which do have their own EFI partition.

"Multiple ESPs" needs context: multiple disks, each of them with one ESP, is OK. On the other hand, one disk with multiple ESPs (i.e. multiple partitions marked with partition type GUID C12A7328-F81F-11D2-BA4B-00A0C93EC93B) can confuse the UEFI firmware, for the reasons stated by Goverp.

grub-install's --efi-directory option can be omitted if the ESP's mountpoint is /boot/efi. Option --target=x86_64-efi can be omitted if the OS that is being used for running grub-install has booted in UEFI mode.

[sMueggli]

Mounting the ESP at /boot can make sense, if you are directly loading the kernel from the firmware. For all other cases I dare to say that using the ESP as /boot partition is not the best case.

Using a bootloader, it is sufficient, if the EFI binary of the bootloader is present on the ESP (at the correct location). In the case of Grub, there is less than 1 MiB needed.

I can think only of very few and very special cases where separated ESPs can make sense. In 99% of all cases, exactly one ESP is needed. It will probably need another decade until the "you need separate ESP partitons" modern fairy tale will disappear.