Date: Fri, 18 Mar 2016 17:45:23 -0400 From: Allan Jude <allanjude@freebsd.org> To: Freddie Cash <fjwcash@gmail.com>, cem@freebsd.org Cc: freebsd-current <freebsd-current@freebsd.org> Subject: Re: boot loaders got fatter in the last few days Message-ID: <56EC76F3.9030906@freebsd.org> In-Reply-To: <CAOjFWZ44sJhggWvQgJQhrPQ=xecTGnAkmUxvSKbgELzXcDTUMg@mail.gmail.com> References: <56EC2DD3.6050803@madpilot.net> <56EC34CE.1000002@freebsd.org> <CAG6CVpUxrmsLg=UROqqo_SKmqrqJMTtqyrij63nxigb5eB=WPA@mail.gmail.com> <CAOjFWZ44sJhggWvQgJQhrPQ=xecTGnAkmUxvSKbgELzXcDTUMg@mail.gmail.com>
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On 2016-03-18 17:41, Freddie Cash wrote: > > On Fri, Mar 18, 2016 at 10:39 AM, Conrad Meyer <cem@freebsd.org > <mailto:cem@freebsd.org>> wrote: > > On Fri, Mar 18, 2016 at 10:03 AM, Allan Jude <allanjude@freebsd.org > <mailto:allanjude@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@gmail.com <mailto:fjwcash@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 -- Allan Jude
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