boot loaders got fatter in the last few days

[Allan Jude]

On 2016-03-18 17:48, Freddie Cash wrote:
>
>
> On Fri, Mar 18, 2016 at 2:45 PM, Allan Jude <allanjude at freebsd.org
> <mailto:allanjude at freebsd.org>> wrote:
>
>     On 2016-03-18 17:41, Freddie Cash wrote:
>
>
>         On Fri, Mar 18, 2016 at 10:39 AM, Conrad Meyer <cem at freebsd.org
>         <mailto:cem at freebsd.org>
>         <mailto:cem at freebsd.org <mailto:cem at freebsd.org>>> wrote:
>
>              On Fri, Mar 18, 2016 at 10:03 AM, Allan Jude
>         <allanjude at freebsd.org <mailto:allanjude at freebsd.org>
>              <mailto:allanjude at freebsd.org
>         <mailto:allanjude at freebsd.org>>> wrote:
>               > On 2016-03-18 12:33, Guido Falsi wrote:
>               >>
>               >> Hi,
>               >>
>               >> I have just update one of my machines and noticed the
>         booloaders
>              files
>               >> got quite fat in the last few days, some by a big margin.
>               >>
>               >> on an updated machine(r296993):
>               >>
>               >> -r--r--r--  1 root  wheel   85794 Mar 18 16:47
>         /boot/gptboot
>               >>
>               >> from a machine I still have not updated(r296719):
>               >>
>               >> -r--r--r--  1 root  wheel   16059 Mar 13 21:01
>         /boot/gptboot
>
>              So the loader grew 70 kB.  How big are your disks?
>
>               >> I noticed because mu gpt boot partition is 64K and
>         gptzfsboot just
>               >> passed 100K.
>               >
>               > This is a side effect of the loader gaining the ability
>         to boot
>              from GELI
>               > encrypted partitions.
>               >
>               > ...
>               >
>               > Maybe we should be putting the GELI enabled boot blocks in a
>              different
>               > filename? I generally wanted to avoid creating a new
>         version of each
>               > bootcode with GELI support.
>
>
>              I think we should just suggest that boot partitions be much
>         larger
>              than 64kB (1MB is still <0.1% of any disk sold today) and
>         not worry
>              about it too much.  Embedded applications can disable GELI
>         loader
>              support to save a few bytes.
>
>
>         ​The boot partition doesn't necessarily need ​
>         ​to be 1 MB (and can't due to some issues with the assembler
>         used right
>         now, or something like that).  We just need to make sure people have
>         slack space in their partition table to expand into in the future.
>
>         Using "-a 1M" in your gpart command to create your first data
>         partition
>         gives you that slack space.
>
>         gpart create -s gpt ada0
>         gpart add -t freebsd-boot -s 256K -l boot ada0
>         gpart add -t freebsd-ufs  -s 10G  -l root -a 1M ada0
>
>         That leaves ~756 KB of free space between the end of the boot
>         partition
>         and the start of the first data partition.  Increasing the size
>         of the
>         boot partition in the future is as easy as (no formatting of disks
>         required):
>
>         gpart delete -i 1 ada0
>         gpart add -t freebsd-boot -s 512K -l boot ada0
>         gpart bootcode -b ... -p ... ada0
>
>         It's a handy pattern I've gotten used to over the years, ever
>         since the
>         first 4K sector harddrives were advertised (as alignment of
>         filesystems
>         was/is *very* important)​.
>
>         Even on disks that will be used solely for ZFS I've taken to
>         creating
>         GPT partitions starting at 1 MB.  And it's saved me from having to
>         reformat disks when moving from a separate root filesystem (no USB
>         sticks) to root-on-ZFS as there was 1 MB of free space at the
>         start of
>         every disk for creating boot partitions.  :)
>
>         --
>         Freddie Cash
>         fjwcash at gmail.com <mailto:fjwcash at gmail.com>
>         <mailto:fjwcash at gmail.com <mailto:fjwcash at gmail.com>>
>
>
>     This also has the handy side effect of allowing you to switch to
>     booting with UEFI, which currently uses an 800kb fat file system
>
>
> ​And I'm pretty sure I read somewhere that the 10.x installer defaults
> to using "-a 1M" when partitioning new disks, although I haven't installed ​
> ​any 10.x systems from scratch yet (just upgrades from 9.x).​
>
> --
> Freddie Cash
> fjwcash at gmail.com <mailto:fjwcash at gmail.com>

Yes, when I built the 10.x 'ZFS' installer mode, I set it to do the 
right thing. I'll have to look into making sure UFS via 'sade' does the 
right thing though

-- 
Allan Jude