Upgrading BIOS Boot Loader

C

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"For systems that boot via BIOS or UEFI CSM and use the GPT partition scheme, bootstrap upgrades are optional unless a ZFS root pool is upgraded (which is discouraged). "

( https://www.freebsd.org/releases/15.1R/upgrading/ )

Can you confirm that this means I do not need to do a bootstrap upgrade?

This is my relevant system info, first the boot method:


# sysctl machdep.bootmethod
machdep.bootmethod: BIOS


And next, the partition info:


# gpart show
=> 40 3565158320 vtbd0 GPT (1.7T)
40 1024 1 freebsd-boot (512K)
1064 3556768768 2 freebsd-ufs (1.7T)
3556769832 8388528 3 freebsd-swap (4.0G)


Based on that information, I could theoretically upgrade the bootcode with the following command:


gpart bootcode -b /boot/pmbr -p /boot/gptboot -i 1 vtbd0


And then doing

shutdown -r now

However, this is optional, correct?

I have been using FreeBSD for over 25 years to host my personal websites, but I have never seen something like this to do between minor version upgrades, hence my caution.

Thank you very much.
 
The biggest thing around bootloader upgrades is "Are you using ZFS for your root device"
If the answer is no, then as SirDice says, update gets bug fixes.

If ZFS then the "commandment" is "make sure you update bootloaders BEFORE doing zpool upgrade on your pools"
 
I'm not on FreeBSD since 25 years, but as long as I recall (let say 12 era), the loaders change at each FreeBSD version, whether it's minor or major; I mean in /boot.

Often pmbr stays the same, that said, but all the others evolve.

The main change here is that the update of the loaders is far well documented than before.

The command you show is correct. And yes, it's optional in your case, but I also recommend to update at each new version.
 
Thank you all for your help!

Hypothetically, is there any way for me to look at the new changes, like diff in some form or fashion, just for my own learning?

I realize they are probably binary, but the bootloader info usually isn't super huge, so maybe I can learn something from the differences anyway, even if binary.

I just don't know how to do the equivalent of "diff" to compare the proposed new data to the old data.

Is there a command I can run to access and compare the contents of what is old and what is going to be new?

Even more amazing, would be if there is some writeup explaining the difference in the existing FreeBSD 15.0 bootloader data and the upcoming FreeBSD 15.1 bootloader data, for my situation with BIOS and GPT.

Thank you again!
 
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