On Fri, Mar 18, 2016 at 2:45 PM, Allan Jude <allanj...@freebsd.org> wrote:
> On 2016-03-18 17:41, Freddie Cash wrote:
>> On Fri, Mar 18, 2016 at 10:39 AM, Conrad Meyer <c...@freebsd.org
>> <mailto:c...@freebsd.org>> wrote:
>> On Fri, Mar 18, 2016 at 10:03 AM, Allan Jude <allanj...@freebsd.org
>> <mailto:allanj...@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
>> >> 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
>> > filename? I generally wanted to avoid creating a new version of
>> > 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
>> 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
>> fjwc...@gmail.com <mailto:fjwc...@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).
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