kern/153173: [zfs] booting from a gzip-compressed dataset doesn't work

[Anonymous]

>Number:         153173
>Category:       kern
>Synopsis:       [zfs] booting from a gzip-compressed dataset doesn't work
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-fs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Wed Dec 15 10:20:08 UTC 2010
>Closed-Date:
>Last-Modified:
>Originator:     Anonymous
>Release:        FreeBSD 9.0-CURRENT amd64
>Organization:
>Environment:
Not documented? Google[1] doesn't return why it's kept unimplemented.
And what seems to be initial zfsboot commit log[2] doesn't help.

[1] http://google.com/search?q=zfs+gzip+boot+freebsd
[2] http://p4db.freebsd.org/changeView.cgi?CH=124081
>Description:
When setting compression globally, i.e. on a root dataset, one has to be
careful as such datasets are not bootable. And dedup doesn't work on
blocks with different compression which limits at how many cycles one
can throw away to save space.

This is a feature request.
>How-To-Repeat:
$ zpool create -O compression=gzip -R /mnt/foo foo gptid/A-B-C-D-E
$ qemu -nographic foo.img
/boot.config: -h
ZFS: unsupported compression algorithm gzip-6
ZFS: i/o error - all block copies unavailable
Invalid format

FreeBSD/x86 boot
Default: foo:/boot/kernel/kernel
boot:

# in case zfsloader is compressed by off/lzjb/zle
$ qemu -nographic foo.img
/boot.config: -h
Consoles: serial port
BIOS drive C: is disk0
BIOS 637kB/130036kB available memory

FreeBSD/x86 ZFS enabled bootstrap loader, Revision 1.1
(foo at bar, Tue Dec 14 00:38:42 UTC 2010)
ZFS: unsupported compression algorithm gzip-6
ZFS: i/o error - all block copies unavailable
start not found
-
ZFS: unsupported compression algorithm gzip-6
ZFS: i/o error - all block copies unavailable
ZFS: unsupported compression algorithm gzip-6
ZFS: i/o error - all block copies unavailable
ZFS: unsupported compression algorithm gzip-6
ZFS: i/o error - all block copies unavailable
ZFS: unsupported compression algorithm gzip-6
ZFS: i/o error - all block copies unavailable
can't load 'kernel'

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OK
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted: