Hi,

Is there a way to install grub to the VBR of an exfat-formatted
partition?

> grub-bios-setup: error: hostdisk//dev/sdb appears to contain a exfat
> filesystem which isn't known to reserve space for DOS-style boot.
> Installing GRUB there could result in FILESYSTEM DESTRUCTION if valuable
> data is overwritten by grub-setup (--skip-fs-probe disables this check,
> use at your own risk).

ExFAT reserves 390 octets (<420o in FAT32) at offset 0x078, plus the
whole second sector, for boot code.
<https://wiki.osdev.org/ExFAT#Boot_Sector_Structure>
Am I correct that grub could put its boot image there and it's just not
implemented?

For context: the goal was to devise a single device structure bootable
"everywhere" (MBR or UEFI, different platforms), with the simplest
possible partitioning (1 part) and accepting iso files >4Go, on a very
widely supported filesystem.
Hence the idea of just one big "ESP" formatted with exFAT. But then
there are further issues:
- Most UEFI firmwares out there only support FAT32, not exFAT, right?
- "Apple machines (like iMac and MacBooks) only accept HFS+ FS on the
ESP." <https://wiki.osdev.org/EFI_System_Partition> Maybe tacking a
second, HFS+-formatted, ESP would convince those machines to boot from the
same device?


Thanks in advance for your comments,
Daniel
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