Date: Fri, 18 Mar 2016 14:48:18 -0700 From: Freddie Cash <fjwcash@gmail.com> To: Allan Jude <allanjude@freebsd.org> Cc: cem@freebsd.org, freebsd-current <freebsd-current@freebsd.org> Subject: Re: boot loaders got fatter in the last few days Message-ID: <CAOjFWZ4UmgAxTHGrpU6ToCSHpW_isRrGLvGnk%2BH%2B49XZfYu7WA@mail.gmail.com> In-Reply-To: <56EC76F3.9030906@freebsd.org> References: <56EC2DD3.6050803@madpilot.net> <56EC34CE.1000002@freebsd.org> <CAG6CVpUxrmsLg=UROqqo_SKmqrqJMTtqyrij63nxigb5eB=WPA@mail.gmail.com> <CAOjFWZ44sJhggWvQgJQhrPQ=xecTGnAkmUxvSKbgELzXcDTUMg@mail.gmail.com> <56EC76F3.9030906@freebsd.org>
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On Fri, Mar 18, 2016 at 2:45 PM, Allan Jude <allanjude@freebsd.org> wrote: > 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 ju= st >> >> 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. >> >> >> =E2=80=8BThe boot partition doesn't necessarily need =E2=80=8B >> =E2=80=8Bto be 1 MB (and can't due to some issues with the assembler use= d 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)=E2=80=8B. >> >> 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 =E2=80=8BAnd I'm pretty sure I read somewhere that the 10.x installer defau= lts to using "-a 1M" when partitioning new disks, although I haven't installed =E2= =80=8B =E2=80=8Bany 10.x systems from scratch yet (just upgrades from 9.x).=E2=80= =8B --=20 Freddie Cash fjwcash@gmail.com
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