Hi: Porting Cramfs on FreeBSD

Dear All,
 I want to port cramfs to freebsd-6.1 ; can anybody give me
some tips
about how to port..


thank you,
with love,
krishnamurthy
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krishnamurthy holla wrote:
 >  I want to port cramfs to freebsd-6.1 ; can anybody
give me
 > some tips about how to port..

I think porting cramfs is not a good idea.  It's GPL'ed,
doesn't fully support POSIX semantics, and has severe
limitations (16 MB maximum file size, 256 MB maximum file
system size).

It is probably better to design a new file system from
scratch (and make it BSD-licensed).

Just my 2 cents.

Best regards
   Oliver

-- 
Oliver Fromme,  secnetix GmbH & Co. KG, Marktplatz 29,
85567 Grafing
Dienstleistungen mit Schwerpunkt FreeBSD: http://www.secnetix.de/bsd

Any opinions expressed in this message may be personal to
the author
and may not necessarily reflect the opinions of secnetix in
any way.

Perl is worse than Python because people wanted it worse.
        -- Larry Wall
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On 09/27/06 08:07, Oliver Fromme wrote:
> krishnamurthy holla wrote:
>  >  I want to port cramfs to freebsd-6.1 ; can
anybody give me
>  > some tips about how to port..
> 
> I think porting cramfs is not a good idea.  It's
GPL'ed,
> doesn't fully support POSIX semantics, and has severe
> limitations (16 MB maximum file size, 256 MB maximum
file
> system size).
> 
> It is probably better to design a new file system from
> scratch (and make it BSD-licensed).
> 
> Just my 2 cents.
> 
> Best regards
>    Oliver
> 


I'm currently working on a tarfs, that will do something
similar to 
this, except it allows you to use a regular tar file as the
file system 
image.  I don't have compression working yet, but that is on
the 
roadmap.  It's also more fully featured than cramfs - it
will support 
the full uid/gids, . and .. directories, hard links, large
file system 
sizes (based on available memory), real timestamps, full
permissions 
(but not extended attributes), and will be BSD licensed.


Eric



-- 
------------------------------------------------------------
------------
Eric Anderson        Sr. Systems Administrator       
Centaur Technology
Anything that works is better than anything that doesn't.
------------------------------------------------------------
------------
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On Wed, Sep 27, 2006 at 03:07:16PM +0200, Oliver Fromme
wrote:
> krishnamurthy holla wrote:
>  >  I want to port cramfs to freebsd-6.1 ; can
anybody give me
>  > some tips about how to port..
> 
> I think porting cramfs is not a good idea.  It's
GPL'ed,
> doesn't fully support POSIX semantics, and has severe
> limitations (16 MB maximum file size, 256 MB maximum
file
> system size).
> 
> It is probably better to design a new file system from
> scratch (and make it BSD-licensed).

For running on a flash card, I'm not sure those limits are
unreasonable.
Also, if you do a implementation from the public data in the
headers, is
that code also under GPL?
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Gary Palmer wrote:
 > Oliver Fromme wrote:
 > > krishnamurthy holla wrote:
 > > >  I want to port cramfs to freebsd-6.1 ; can
anybody give me
 > > > some tips about how to port..
 > > 
 > > I think porting cramfs is not a good idea.  It's
GPL'ed,
 > > doesn't fully support POSIX semantics, and has
severe
 > > limitations (16 MB maximum file size, 256 MB
maximum file
 > > system size).
 > > 
 > > It is probably better to design a new file system
from
 > > scratch (and make it BSD-licensed).
 > 
 > For running on a flash card, I'm not sure those limits
are unreasonable.

Nowadays, flash cards of 1 GB or even larger are pretty much
standard.  Therefore I think that a 256 MB file system limit
is not reasonable.  A file size limit of 16 Mb is even less
reasonable, IMHO.

(Remember Bill Gate's famous statement "640 KB should
be
enough for everybody"? 

 > Also, if you do a implementation from the public data
in the headers, is
 > that code also under GPL?

No, I don't think so (but I'm not a lawyer).  But he wrote
that he wanted "to port cramfw", not to do an
implementation
of his own, which is a different thing.  But maybe he really
meant the latter.

Best regards
   Oliver

-- 
Oliver Fromme,  secnetix GmbH & Co. KG, Marktplatz 29,
85567 Grafing
Dienstleistungen mit Schwerpunkt FreeBSD: http://www.secnetix.de/bsd

Any opinions expressed in this message may be personal to
the author
and may not necessarily reflect the opinions of secnetix in
any way.

"A language that doesn't have everything is actually
easier
to program in than some that do."
        -- Dennis M. Ritchie
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Eric Anderson wrote:
 > I'm currently working on a tarfs, that will do
something similar to 
 > this, except it allows you to use a regular tar file
as the file system 
 > image.

That's cool.  I'm looking forward to it.

 > I don't have compression working yet, but that is on
the 
 > roadmap. [...] large file system sizes (based on
available
 > memory)

Hm.  Does that mean that the whole (uncompressed) FS image
will have to fit into memory?  That would be a disadvantage
compared to cramfs.  Cramfs doesn't compress the whole FS
as one object (like .tar.gz), but it compresses it page-by-
page, so every page can be uncompressed independently, and
memory usage is very low, which is good for small embedded
applications.

Best regards
   Oliver

-- 
Oliver Fromme,  secnetix GmbH & Co. KG, Marktplatz 29,
85567 Grafing
Dienstleistungen mit Schwerpunkt FreeBSD: http://www.secnetix.de/bsd

Any opinions expressed in this message may be personal to
the author
and may not necessarily reflect the opinions of secnetix in
any way.

"... there are two ways of constructing a software
design:  One way
is to make it so simple that there are _obviously_ no
deficiencies and
the other way is to make it so complicated that there are no
_obvious_
deficiencies."        -- C.A.R. Hoare, ACM Turing Award
Lecture, 1980
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On 09/27/06 12:44, Oliver Fromme wrote:
> Eric Anderson wrote:
>  > I'm currently working on a tarfs, that will do
something similar to 
>  > this, except it allows you to use a regular tar
file as the file system 
>  > image.
> 
> That's cool.  I'm looking forward to it.
> 
>  > I don't have compression working yet, but that is
on the 
>  > roadmap. [...] large file system sizes (based on
available
>  > memory)
> 
> Hm.  Does that mean that the whole (uncompressed) FS
image
> will have to fit into memory?  That would be a
disadvantage
> compared to cramfs.  Cramfs doesn't compress the whole
FS
> as one object (like .tar.gz), but it compresses it
page-by-
> page, so every page can be uncompressed independently,
and
> memory usage is very low, which is good for small
embedded
> applications.

No, only inode+direntries need to fit into memory.  So an FS
with 
1million inodes might take .5MB of memory (estimate).

Eric



-- 
------------------------------------------------------------
------------
Eric Anderson        Sr. Systems Administrator       
Centaur Technology
Anything that works is better than anything that doesn't.
------------------------------------------------------------
------------
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how are use geom_uzip(4)/mkuzip ? it`s seem to be equal
cramfs. 


÷ óÒÄ, 27.09.2006, × 15:26, krishnamurthy holla ÐÉÛÅÔ:
> Dear All,
>  I want to port cramfs to freebsd-6.1 ; can anybody
give me some tips
> about how to port..
> 
> 
> thank you,
> with love,
> krishnamurthy
> _______________________________________________
> freebsd-fsfreebsd.org mailing list
> 
http://lists.freebsd.org/mailman/listinfo/freebsd-fs
> To unsubscribe, send any mail to
"freebsd-fs-unsubscribefreebsd.org"
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Dear Sir,
 Thank u for ur info,
   i need some docs so that i can implement cramfs / tarfs
on my own on
FreeBSD. Since i am new to FreeBSD and even i am not Getting
docs about how
to implement filesystems in feebsd ...


with love
krishnamurthy


On 9/28/06, Alex Lyashkov <umkasevcity.net> wrote:
>
> how are use geom_uzip(4)/mkuzip ? it`s seem to be equal
cramfs.
>
>
> ÷ óÒÄ, 27.09.2006, × 15:26, krishnamurthy holla ÐÉÛÅÔ:
> > Dear All,
> >  I want to port cramfs to freebsd-6.1 ; can
anybody give me some tips
> > about how to port..
> >
> >
> > thank you,
> > with love,
> > krishnamurthy
> > _______________________________________________
> > freebsd-fsfreebsd.org mailing list
> > 
http://lists.freebsd.org/mailman/listinfo/freebsd-fs
> > To unsubscribe, send any mail to "
freebsd-fs-unsubscribefreebsd.org"
>
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Eric Anderson <andersoncenttech.com> writes:
> No, only inode+direntries need to fit into memory.  So
an FS with
> 1million inodes might take .5MB of memory (estimate).

How are you going to do that?  Whenever you want to read a
file,
you'll have to start decompressing the entire tarball from
the
beginning, since it's a single gzip stream.  You can't just
seek to an
arbitrary position in the stream and start decompressing
there.

DES
-- 
Dag-Erling Smørgrav - desdes.no
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