Is it possible to have the ESP on an sdcard?

Ask Fedora
1

ESP and XBOOTLDR on an sdcard works now with sd-boot when formatted FAT so UEFI directly supports access.

2

https://www.intel.com/content/dam/doc/product-specification/efi-v1-10-specification.pdf

4

This is how researchers do it. . . Especially when traveling. I think you can find some Kali Linux tutorials on how to achieve just this. I “had” a script for this for a Fedora Security spin, but I am not on that machine at the moment.

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5

To my knowledge, grub does not support being installed on a single ESP. It requires three partitions – BIOSBOOT, /boot, and /boot/efi. Can you use sd-boot? sd-boot will work happily on a single partiton.

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7

I should have mentioned that. . . I’m on systemd-boot

11

I use a SD card with /boot now to get around Dell’s UEFI on internal devices only thing (no Legacy boot from NVMe).

With discarded NVMe/SD, with Anaconda I select both drives, custom partitioning, standard, delete home, boot, and root (only thing left in list is BIOS boot), re-add boot (auto sets/fills SD), add root (auto sets/fills to NVMe), and done (I have boot and root as XFS currently):

NAME        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
mmcblk0     179:0    0   1.9G  0 disk 
├─mmcblk0p1 179:1    0     1M  0 part 
└─mmcblk0p2 179:2    0   1.9G  0 part /boot
zram0       252:0    0     8G  0 disk [SWAP]
nvme0n1     259:0    0 953.9G  0 disk 
└─nvme0n1p1 259:1    0 953.9G  0 part /

I have a RTS525A and with most of my SD cards I got some voltage switch error in dmesg on-insert; not sure what it’s about but I kept switching cards until I found some that didn’t have the error, then chose a 2GB one. blkdiscard ideally should be instant for a quick test of speed.

I think using XFS on /boot has GRUB report something about writing outside the partition (don’t recall seeing it with ext4 on SD); I’ve seen it occasionally over a year on NVMe and different computers and assume it’s harmless :stuck_out_tongue:

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