JFFS2 on eCos

JFFS2 on eCos

[David Woodhouse]

Is anyone still interested in JFFS2 on eCos? I've just committed a bunch
of improvements to mount time and memory usage, and I'm hoping that
someone will step forward to update and look after the eCos port.

We've abandoned the CVS repository which was used for development of
JFFS2, and we're doing JFFS2 development in a git tree based on the
Linux kernel (http://git.infradead.org/?p=mtd-2.6.git)

This means that the eCos code is no longer in CVS right next to the
Linux version. We used to have a 'mkepk.sh' script which would create an
epk from what's in CVS -- perhaps we could replace that with a git
repository which automatically pulls in core JFFS2 changes from the
Linux tree, but also contains the eCos files. I'm happy enough to give
accounts to whoever steps forward as JFFS2/eCos maintainers to do
something like that on git.infradead.org, or give whatever assistance is
otherwise useful.

-- 
dwmw2

Re: JFFS2 on eCos

[Gary Thomas]

On Fri, 2006-05-26 at 00:26 +0100, David Woodhouse wrote:
> Is anyone still interested in JFFS2 on eCos? I've just committed a bunch
> of improvements to mount time and memory usage, and I'm hoping that
> someone will step forward to update and look after the eCos port.
> 
> We've abandoned the CVS repository which was used for development of
> JFFS2, and we're doing JFFS2 development in a git tree based on the
> Linux kernel (http://git.infradead.org/?p=mtd-2.6.git)
> 
> This means that the eCos code is no longer in CVS right next to the
> Linux version. We used to have a 'mkepk.sh' script which would create an
> epk from what's in CVS -- perhaps we could replace that with a git
> repository which automatically pulls in core JFFS2 changes from the
> Linux tree, but also contains the eCos files. I'm happy enough to give
> accounts to whoever steps forward as JFFS2/eCos maintainers to do
> something like that on git.infradead.org, or give whatever assistance is
> otherwise useful.

Put my head on the block :-)  Tell me what needs to be done and how
and I'll make sure it happens.

-- 
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------

Re: JFFS2 on eCos

[David Woodhouse]

On Fri, 2006-05-26 at 03:55 -0600, Gary Thomas wrote:
> Put my head on the block :-)  Tell me what needs to be done and how
> and I'll make sure it happens. 

OK, thanks.... I'll give you a quick overview of what we have, and what
needs doing.

When we first did the eCos port, I split Linux-specific stuff from
'core' JFFS2 code, putting them into separate files in the CVS tree.
We added an 'ecos' subdirectory, containing jffs2.cdl and the
eCos-specific files to match the Linux ones. I think you've seen all
that anyway.

What I need primarily is someone to take overall responsibility for
keeping the eCos files up to date when we change stuff that affects them
-- and to keep them up to date with eCos itself. Presumably also to
merge JFFS2 code into the eCos tree.

That task doesn't have to be all coding -- it can also include LARTing
me (and other JFFS2 developers) if/when we break the eCos build without
reason, without fixing up the eCos side ourselves, and/or without at
least giving you a heads-up.

(For example, if you refer to the changes I've made in the git tree in
the last few days, I would expect a kicking for putting the new
jffs2_prealloc_raw_node_refs() function into malloc.c, which is an
OS-specific file, instead of putting it into a shared file. It's a
function which should be the same in both cases. I'll fix that.)

How you do this technically is ultimately up to you. What I'd probably
suggest is that we should keep the eCos version on git.infradead.org, so
it is immediately to hand and you can quite reasonably expect people to
keep it working. With a little bit of git hacking, we should be able to
set up a git tree which contains just the OS-independent files, and
which inherits changes automatically from the main mtd-2.6.git tree.
Then we can do a git tree for the eCos version which merges from that as
and when appropriate.

If that's how you want to do it, I'll go and set up the script to do
that JFFS2-only tree, and set up the eCos repository based on that and
the latest version of the eCos-specific files from CVS.


Aside from setting that up, what needs doing right now is to make it
build on eCos again, since I assume it doesn't. Take the JFFS2 files
from the mtd-2.6.git tree, add the latest eCos files (which were last
updated in July of last year), and make them work.

You might benefit from doing that incrementally -- perhaps starting with
the version in the 2.6.16 kernel, which is before all the changes I've
just made, but _after_ the introduction of the 'erase block summary'
code. Alternatively, you might prefer just to do it all in one fell
swoop with the current code. 

-- 
dwmw2

Re: JFFS2 on eCos

[David Woodhouse]

On Fri, 2006-05-26 at 14:01 +0100, David Woodhouse wrote:
> How you do this technically is ultimately up to you. What I'd probably
> suggest is that we should keep the eCos version on git.infradead.org, so
> it is immediately to hand and you can quite reasonably expect people to
> keep it working. With a little bit of git hacking, we should be able to
> set up a git tree which contains just the OS-independent files, and
> which inherits changes automatically from the main mtd-2.6.git tree.
> Then we can do a git tree for the eCos version which merges from that as
> and when appropriate.

I've created git://git.infradead.org/~dwmw2/jffs2-ecos-core.git which
contains just the JFFS2 files, moved into a 'src/' directory. It
preserves the full revision history of those files from the kernel, and
it's automatically updated from the kernel tree every night. It's
browsable at http://git.infradead.org/?p=users/dwmw2/jffs2-ecos-core.git

The script which does it, if you're interested, is at
http://david.woodhou.se/extract-jffs2-git.sh -- we can redo the whole
thing with a different set of $JFFS2FILES if you want.

I've also created another tree which derives from the above, and added
the eCos-specific files to it. That one is 'jffs2-ecos.git' in the same
directory.

The idea is that you can merge changes (with 'git pull') from the
'jffs2-ecos-core' tree into the working 'jffs2-ecos' tree.

I haven't based the jffs2-ecos tree on the _current_ state of the
exported jffs2-ecos-core; it's based on a version from November last
year, which corresponds to the Andrew's last update to the eCos code in
my tree -- this means that we have some expectation that it might
actually build and work in eCos.

It's probably work making sure that _does_ actually work before starting
to pull in further changes from the upstream JFFS2 codebase. 

You might also want to pull the upstream changes in incrementally --
perhaps starting with commit #43220493be8f4c6b99508e78064fa557b005577c,
which includes eraseblock summary support but not yet all the other
changes I've made recently. Alternatively, you might prefer just to do
it all in one, so that we can make changes to the upstream JFFS2 tree to
make life easier.

-- 
dwmw2

Re: JFFS2 on eCos

[David Woodhouse]

On Mon, 2006-05-29 at 15:32 +0100, David Woodhouse wrote:
> You might also want to pull the upstream changes in incrementally --
> perhaps starting with commit #43220493be8f4c6b99508e78064fa557b005577c,
> which includes eraseblock summary support but not yet all the other
> changes I've made recently. 

I've rebuilt the repositories because I'd forgotten to include the files
which are now in the doc/ directory of the eCos tree -- TODO,
README.Locking and LICENCE.

The commit which corresponds to the inclusion of summary support and
which might be a useful point to sync up with would now be
2f2d792728baed0421531af8c6b83085523913e2

-- 
dwmw2

Re: JFFS2 on eCos

[David Woodhouse]

On Mon, 2006-05-29 at 15:32 +0100, David Woodhouse wrote:
> I've created git://git.infradead.org/~dwmw2/jffs2-ecos-core.git which
> contains just the JFFS2 files, moved into a 'src/' directory. It
> preserves the full revision history of those files from the kernel, and
> it's automatically updated from the kernel tree every night. It's
> browsable at http://git.infradead.org/?p=users/dwmw2/jffs2-ecos-core.git
> 
> The script which does it, if you're interested, is at
> http://david.woodhou.se/extract-jffs2-git.sh -- we can redo the whole
> thing with a different set of $JFFS2FILES if you want.
> 
> I've also created another tree which derives from the above, and added
> the eCos-specific files to it. That one is 'jffs2-ecos.git' in the same
> directory.
> 
> The idea is that you can merge changes (with 'git pull') from the
> 'jffs2-ecos-core' tree into the working 'jffs2-ecos' tree.
> 
> I haven't based the jffs2-ecos tree on the _current_ state of the
> exported jffs2-ecos-core; it's based on a version from November last
> year, which corresponds to the Andrew's last update to the eCos code in
> my tree -- this means that we have some expectation that it might
> actually build and work in eCos.
> 
> It's probably work making sure that _does_ actually work before starting
> to pull in further changes from the upstream JFFS2 codebase.  

Any progress on this?

-- 
dwmw2

Re: JFFS2 on eCos

[Gary Thomas]

On Wed, 2006-06-21 at 14:21 +0100, David Woodhouse wrote:
> On Mon, 2006-05-29 at 15:32 +0100, David Woodhouse wrote:
> > I've created git://git.infradead.org/~dwmw2/jffs2-ecos-core.git which
> > contains just the JFFS2 files, moved into a 'src/' directory. It
> > preserves the full revision history of those files from the kernel, and
> > it's automatically updated from the kernel tree every night. It's
> > browsable at http://git.infradead.org/?p=users/dwmw2/jffs2-ecos-core.git
> > 
> > The script which does it, if you're interested, is at
> > http://david.woodhou.se/extract-jffs2-git.sh -- we can redo the whole
> > thing with a different set of $JFFS2FILES if you want.
> > 
> > I've also created another tree which derives from the above, and added
> > the eCos-specific files to it. That one is 'jffs2-ecos.git' in the same
> > directory.
> > 
> > The idea is that you can merge changes (with 'git pull') from the
> > 'jffs2-ecos-core' tree into the working 'jffs2-ecos' tree.
> > 
> > I haven't based the jffs2-ecos tree on the _current_ state of the
> > exported jffs2-ecos-core; it's based on a version from November last
> > year, which corresponds to the Andrew's last update to the eCos code in
> > my tree -- this means that we have some expectation that it might
> > actually build and work in eCos.
> > 
> > It's probably work making sure that _does_ actually work before starting
> > to pull in further changes from the upstream JFFS2 codebase.  
> 
> Any progress on this?

I'm trying :-)  However, other stuff keeps getting in the way.
I'll do my best to move it up the heap...

-- 
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------

Re: JFFS2 on eCos

[David Woodhouse]

On Mon, 2006-05-29 at 10:16 +0800, Chi Xiaobo wrote:
> Hi, david, do you need more than one guy to do this? I am also
> interesting in this.

I'm going to let Gary take overall responsibility and own the git tree.

If you'd like to work on it too, I'm sure that would be very much
appreciated. Please send me a SSH public key and I'll set you up with an
account on git.infradead.org, so that you can publish your changes for
Gary to pull.

-- 
dwmw2