On Friday, May 05, 2017 11:01:03 PM Toomas Soome wrote: > > > On 5. mai 2017, at 22:07, Julian Elischer <jul...@freebsd.org> wrote: > > > > Subject says it all really, is this an option at this time? > > > > we'd like to try boot the main zfs root partition and then fall back to a > > small UFS based recovery partition.. is that possible? > > > > I know we could use grub but I'd prefer keep it in the family. > > > > > > > > > it is, sure. but there is an compromise to be made for it. > > Lets start with what I have done in illumos port, as the idea there is > exactly about having as “universal” binaries as possible (just the binaries > are listed below to get the size): > > -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 > > the loader (bios/efi) is built with full complement - zfs, ufs, dosfs, > cd9660, nfs, tftp + gzipfs. The cdboot is starting zfsloader (thats trivial > string change). > > 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. Also I am > building gptzfsboot with libstand and libi386 to get as much shared code as > possible - which has both good and bad sides, as usual;) > > 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). > > As the freebsd-boot is currently created 512k, the size is not an issue. 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 was first written, but I would much rather have a merged gptboot binary that supports 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 boot2, > just that we can not use those blocks for more universal cases and eventually > those special cases will diminish. Yes, the BSD label stuff is stuck with a smaller size, but GPT should support unified bootstraps. -- John Baldwin _______________________________________________ freebsd-current@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
