Date: Mon, 08 May 2017 11:10:50 -0700 From: John Baldwin <jhb@freebsd.org> To: freebsd-current@freebsd.org Cc: Toomas Soome <tsoome@me.com>, Julian Elischer <julian@freebsd.org>, Toomas Soome <tsoome@freebsd.org> Subject: Re: bootcode capable of booting both UFS and ZFS? Message-ID: <2078108.OFyxUdmrtS@ralph.baldwin.cx> In-Reply-To: <053354DF-651F-423C-8057-494496DA3B91@me.com> References: <963c5c97-2f92-9983-cf90-ec9d59d87bba@freebsd.org> <053354DF-651F-423C-8057-494496DA3B91@me.com>
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On Friday, May 05, 2017 11:01:03 PM Toomas Soome wrote: >=20 > > On 5. mai 2017, at 22:07, Julian Elischer <julian@freebsd.org> wrot= e: > >=20 > > Subject says it all really, is this an option at this time? > >=20 > > we'd like to try boot the main zfs root partition and then fall bac= k to a small UFS based recovery partition.. is that possible? > >=20 > > I know we could use grub but I'd prefer keep it in the family. > >=20 > >=20 > >=20 >=20 >=20 > it is, sure. but there is an compromise to be made for it. >=20 > Lets start with what I have done in illumos port, as the idea there i= s exactly about having as =E2=80=9Cuniversal=E2=80=9D binaries as possi= ble (just the binaries are listed below to get the size): >=20 > -r-xr-xr-x 1 root sys 171008 apr 30 19:55 bootia32.efi > -r-xr-xr-x 1 root sys 148992 apr 30 19:55 bootx64.efi > -r--r--r-- 1 root sys 1255 okt 25 2015 cdboot > -r--r--r-- 1 root sys 154112 apr 30 19:55 gptzfsboot > -r-xr-xr-x 1 root sys 482293 mai 2 21:10 loader32.efi > -r-xr-xr-x 1 root sys 499218 mai 2 21:10 loader64.efi > -r--r--r-- 1 root sys 512 okt 15 2015 pmbr > -r--r--r-- 1 root sys 377344 mai 2 21:10 pxeboot > -r--r--r-- 1 root sys 376832 mai 2 21:10 zfsloader >=20 > the loader (bios/efi) is built with full complement - zfs, ufs, dosfs= , cd9660, nfs, tftp + gzipfs. The cdboot is starting zfsloader (thats t= rivial string change). >=20 > The gptzfsboot in illumos case is only built with zfs, dosfs and ufs = - as it has to support only disk based media to read out the loader. Al= so I am building gptzfsboot with libstand and libi386 to get as much sh= ared code as possible - which has both good and bad sides, as usual;) >=20 > The gptzfsboot size means that with ufs the dedicated boot partition = is needed (freebsd-boot), with zfs the illumos port is always using the= 3.5MB boot area after first 2 labels (as there is no geli, the illumos= does not need dedicated boot partition with zfs). >=20 > As the freebsd-boot is currently created 512k, the size is not an iss= ue. Also using common code does allow the generic partition code to be = used, so GPT/MBR/BSD (VTOC in illumos case) labels are not problem. The intention btw of the larger size for gptboot is so we could have a = merged gptboot / gptzfsboot. I don't think ZFS was in FreeBSD when gptboot wa= s first written, but I would much rather have a merged gptboot binary that supp= orts both. It just needs some logic for what to pick if it sees both. (It = would also be nice to axe zfsloader and just pass a different KARGS_FLAG_FOO = in to select ZFS as the default boot device to /boot/loader, but zfsloader is= probably too baked into the system at this point.) > Also note that we can still build the smaller dedicated blocks like b= oot2, just that we can not use those blocks for more universal cases an= d eventually those special cases will diminish. Yes, the BSD label stuff is stuck with a smaller size, but GPT should s= upport unified bootstraps. --=20 John Baldwin
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