[ANN] Squashfs tools 4.1 released

[ANN] Squashfs tools 4.1 released

[Phillip Lougher]

Hi,

I'm pleased to announce the release of Squashfs tools 4.1.  This release
adds support for extended attributes (XATTRs), and LZMA and LZO compression.
There's also new pseudo file features and the usual bug fixes.

The release can be downloaded from http://sourceforge.net/projects/squashfs.


Compatibility
------------

Mksquashfs 4.1 generates 4.0 filesystems.  These filesystems are fully
compatible/interchangable with filesystems generated by Mksquashfs 4.0 and are
mountable on 2.6.29 and later kernels.

Extended attributes (xattrs)
----------------------------

Squashfs file systems now have extended attribute support.  The
extended attribute implementation has the following features:

1. Layout can store up to 248 bytes of compressed xattr data.
2. Number of xattrs per inode unlimited.
3. Total size of xattr data per inode 248 bytes of compressed data.
4. Up to 4 Gbytes of data per xattr value.
5. Inline and out-of-line xattr values supported for higher performance
    in xattr scanning (listxattr & getxattr), and to allow xattr value
    de-duplication.
6. Both whole inode xattr duplicate detection and individual xattr value
    duplicate detection supported.  These can obviously nest, file C's
    xattrs can be a complete duplicate of file B, and file B's xattrs
    can be a partial duplicate of file A.
7. Xattr name prefix types stored, allowing the redundant "user.", "trusted."
    etc. characters to be eliminated and more concisely stored.
8. Support for files, directories, symbolic links, device nodes, fifos
    and sockets.

Extended attribute support is in 2.6.35 and later kernels.  File systems
with extended attributes can be mounted on 2.6.29 and later kernels, the
extended attributes will be ignored with a warning.

LZMA and LZO compression
------------------------

Squashfs now supports LZMA and LZO compression.

LZO support is in 2.6.36 and newer kernels.  LZMA is not yet in mainline.


New pseudo file support
-----------------------

Mksquashfs supports pseudo files, these allow fake files, directories, character
and block devices to be specified and added to the Squashfs filesystem being
built, rather than requiring them to be present in the source directories.
This, for example, allows device nodes to be added to the filesystem without
requiring root access.

Mksquashfs 4.1 adds support for "dynamic pseudo files" and a modify operation.
Dynamic pseudo files allow files to be dynamically created when Mksquashfs
is run, their contents being the result of running a command or piece of
shell script.  The modifiy operation allows the mode/uid/gid of an existing
file in the source filesystem to be modified.


Phillip

how to increase memory limit reduced at boot-time by "mem"

[CEVAN Ondrej]

Hi all!

If the upper memory limit is reduced at booting by using the kernel command
line parameter "mem" is there a way how this memory limit could be increased
at some later point of kernel execution? In other words, if I exclude the
upper part of system memory from kernel's use at boot time, can I reclaim it
back at some later point? 

Particularly I am interested if this would work on the PowerPC and ARM
architecture, or is it not architecture depending?

Thanks a lot for your answer!

Ondrej

Re: how to increase memory limit reduced at boot-time by "mem"

[Geert Uytterhoeven]

On Fri, Sep 24, 2010 at 14:30, CEVAN Ondrej <Ondrej.CEVAN@frequentis.com> wrote:
> If the upper memory limit is reduced at booting by using the kernel command
> line parameter "mem" is there a way how this memory limit could be increased
> at some later point of kernel execution? In other words, if I exclude the
> upper part of system memory from kernel's use at boot time, can I reclaim it
> back at some later point?
>
> Particularly I am interested if this would work on the PowerPC and ARM
> architecture, or is it not architecture depending?

You can use memory hotplugging to add the memory later.
As this has been used on e.g. PS3, it should work on PowerPC.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds