https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=203707
Bug ID: 203707
Summary: [patch] make makefs(8) more compatible with
geom_uncompress
Product: Base System
Version: 10.2-STABLE
Hardware: Any
OS: Any
Status: New
Keywords: patch
Severity: Affects Some People
Priority: ---
Component: bin
Assignee: [email protected]
Reporter: [email protected]
Keywords: patch
Created attachment 161924
--> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=161924&action=edit
new option -r roundup
While trying to run FreeBSD/mips on some device having very small flash media,
one is forced to compress file system with mkulzma(8) utility. It is desirable
to specify small UFS block/fragment sizes like 4096/512 bytes for makefs(8) and
big compression block size like 65535 bytes to mkulzma at the same time. Then
one obtains very good comression ratios (like 75% and more) but faces the
following problem.
geom_uncompress kernel module reports GEOM provider size rounded up to its
compression block size. Generally, this changes original media size and now it
fails to match the size of embedded UFS file system that leads to other
problems, f.e. geom_label kernel module does not like this and skips the file
system while tasting the GEOM and looking for UFS label.
This makes it impossible to refer to the file system using known UFS label
instead of something like /dev/map/rootfs.uncompress.
The following patch introduces new command line option "-r roundup" for makefs
that makes it round up the image to specified block size. Hence,
geom_uncompress does not change GEOM media size for images rounded that way and
geom_label accepts such GEOMs just fine.
With the patch applied, one can use following commands:
makefs -t ffs -r 65536 -o bsize=4096,fsize=512,label=flash optimization=space
fs.img fs
mkulzma -s 65536 -o fs.img.ulzma fs.img
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