Minimum size of freebsd-boot

Polytropon freebsd at
Thu Jun 21 16:48:35 UTC 2018

On Thu, 21 Jun 2018 21:45:38 +0530, Manish Jain wrote:
> Under GPT, FreeBSD needs a freebsd-boot partition of max size 512 KB. Is 
> there a minimum size too ?

The minimum size depends on what you require on the
/boot partition. The ZFS loader is bigger than the
classic UFS-only loader. Older FreeBSD documentation
suggested a smaller size (approx. 40 kB) which today
probably wouldn't be sufficient.

Note that the whole partition is loaded into memory.
And partition alignment is also important. That's why
512 kB is a good value (2^9). :-)

Subsequent partitions typically start at the next
multiple of 1 MB (which fits both 512 B and 4 kB
sector size). So you could try to create a smaller
/boot partition, but the next one, maybe / or swap,
would start at 1 MB anyway.

Also see:

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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