iT/OS 2006 - Implications for 'extrootfs'

[dattani98]

Question for the 770 'gurus' out there -

I used wolframs script to (a) Extend Root and then (b) Create a 24MB swapfile on a 200MB partition on my 1GB RS MMC. Its been working great and I can have loads of aps open at the same time.

Does anyone know if upgrading to OS/iT2006 will:

(1) Wipe out this script and the operation of the swapfile
(2) Disbale R&D mode

In other words - will I have to 'become root' again (not just sudo gainroot but the whole shebang with the flasher in Linux), then re-install & run the extrootfs script? Will I need to repartition the RS MMC?

Thanks!!

[aflegg]

No-one really knows yet. Some educated guesses:


The R&D flag will probably remain - but getting root from scratch should be trivial with the new package management. Effectively a simple package could be produced with a setuid shell if root access is blocked as now.
The extrootfs using symlinks[1] will need to be re-applied, but it will also need rethinking: /var/lib/install will no longer exist and packages are "intermingled" with the system files. This will make them very tricky to extract
There is suspicion that swap will be officially supported due to a line in the new marketing material. This could just be typically confusing marketting, though.


Also, FWIW the forum isn't so big that spamming the same thread all over the place is worthwhile.

HTH,

Andrew

[1] Personally, I prefer the approach using a UnionFS: http://www.heike-zimmerer.de/software/mmc-unionfs.html

[dattani98]

Thanks. I wasnt spamming - just trying to increase the chances of getting a reply. Point noted.

[Eleon_Gonzales]

So is the 2006 OS available for download yet? It doesn't show up for me... I'd really like to get google talk going so I can talk to my girlfriend while she is in hong kong for the next two months.

If not now, when? It's second quarter and it says on the site that the 770s are shipping with the 2006 OS.

[Coolty]

I don't know, eleon. I was wondering the same thing myself

[aflegg]

June (although an exact date isn't pinned down yet)

[RogerS]

Nokia has been saying 2006 since last May, and 2006Q2 since around November or December, IIRC. For a brief period they switched from saying "first quarter" to saying "first half" of 2006, then went to "second quarter." They've been very explicit about this all along.

[bradb]

[1] Personally, I prefer the approach using a UnionFS: http://www.heike-zimmerer.de/software/mmc-unionfs.html

Andrew-

Thanks for the tip. This is an excellent solution - very elegant. I hope nokia uses this in iT/OS 2006.

Brad.

[neiljerram]

[1] Personally, I prefer the approach using a UnionFS

Yes. I'm not sure I fully understand unionfs yet, but it seems to me that it is preferable to using symbolic links for whole subtrees (a la extrootfs) for the following reason.

With the symbolic link approach, the risk you take is that something important about the contents/layout of the linked subtree may change in the next OS upgrade. After such an upgrade, when you run the script to recreate the links pointing to your MMC, you will effectively back out those important changes, and this may result in some part of the OS not working properly.

With the unionfs approach, there is still a similar risk, but only at the level of individual files, not of whole subtrees. (For example if you install something that causes a modified version of the dpkg status file to be written to your MMC, shadowing the one on the internal memory, and then an OS upgrade changes something in the shipped status file, you risk missing that change.)

So in summary, even though there is risk both ways, it seems to me that there's less scope for problematic conflicts with unionfs than there is with symbolic links.

Does that all sound correct, or have I missed some other factors here that would modify the risks?

Finally, a plain question. Does the unionfs approach require that the root filesystem is initially mounted (i.e. during boot) as part of a unionfs, or is it possible to convert the existing, mounted root filesystem to unionfs later on? (I'd be interested to see the precise commands, if someone can post them.)

Regards - Neil

[aflegg]

So in summary, even though there is risk both ways, it seems to me that there's less scope for problematic conflicts with unionfs than there is with symbolic links.

Indeed. It's also possible to get a working 770 by removing the MMC card: the unions just won't be mounted when you boot and you won't have dangling symlinks instead.

Finally, a plain question. Does the unionfs approach require that the root filesystem is initially mounted (i.e. during boot) as part of a unionfs, or is it possible to convert the existing, mounted root filesystem to unionfs later on?

Effectively you can mount the unions at any time, but the setup script includes an /etc/rc2.d script to mount them at boot, if the MMC card is present.

Once mounted the files present in the union take precedence over those on the disk.

So, in my /home/user I have both the Ice Age 2 trailer which is in /home/user in the internal flash; and "Rise of the Cybermen" which is on my MMC card. To the 770's file manager and video player they're both in /home/user; even if - in reality - one's actually on the MMC.

HTH,

Andrew

[beaulieu]

can you do set-up the MMC card from a computer running windows ,

it seems to be that you need Linux, which I do not have...

thabks

Beaulieu

[neiljerram]

Indeed. It's also possible to get a working 770 by removing the MMC card: the unions just won't be mounted when you boot and you won't have dangling symlinks instead.

Good point.

Effectively you can mount the unions at any time, but the setup script includes an /etc/rc2.d script to mount them at boot, if the MMC card is present.

I'm afraid I still don't get the detail of this. I assume that when the 770 boots, the root filesystem is mounted as ext3 (or similar) on /. Then later, what we want is for the union as a whole to be mounted on /, and the old root filesystem to be one of the constituents of the union. So I'm curious about exactly how this is achieved, because my guess is that "mount -t unionfs -o dirs=/ unionfs /" would not work (because of recursion).

So, in my /home/user I have both the Ice Age 2 trailer which is in /home/user in the internal flash; and "Rise of the Cybermen" ...

Really? And I'm using your preset encoder to watch series 1 again on the tube. :)

Regards - Neil

[aflegg]

can you do set-up the MMC card from a computer running windows ,

it seems to be that you need Linux, which I do not have...

Yes, you do - on the 770 itself. After faffing around with Mac OS X and VMware and Ubuntu through a dodgy card reader, I settled on using cfdisk on the 770 itself: job was done in 5 minutes :-)

I'm afraid I still don't get the detail of this. I assume that when the 770 boots, the root filesystem is mounted as ext3 (or similar) on /. Then later, what we want is for the union as a whole to be mounted on /, and the old root filesystem to be one of the constituents of the union. So I'm curious about exactly how this is achieved, because my guess is that "mount -t unionfs -o dirs=/ unionfs /" would not work (because of recursion).

You only define unions for locations you want, so I have unions for:


/home/user
/var/lib/install
/var/lib/gconf
/usr/share/themes
/etc/others-menu


As you say, unionising / itself could lead to interesting effects (but I assume unionfs would not recurse into itself).

[Doctor Who]Really? And I'm using your preset encoder to watch series 1 again on the tube :-)

Cool. I thought Christopher Ecclestone was great, but David Tennant's even better, IMHO...

What line? I've not yet seen another 770 when I'm on the tube, so I'll keep an eye out ;-)

Cheers,

Andrew

[dattani98]

can you do set-up the MMC card from a computer running windows ,

it seems to be that you need Linux, which I do not have...

thabks

Beaulieu

You dont necessarily need to have linux installed - I run a windows pc with virtual machine player (www.vmware.com/products/player/) . All I did was download a linux virtual appliance from the same site and I was able o follow the instructions for becoming root etc. You can also run Ubuntu or some other 'live cd'.

[dattani98]

and as Andrew said - you can use 'cfdisk' from xterm on the 770 itself which is probably the quickest and most sensible solution.

[hczim]

my guess is that "mount -t unionfs -o dirs=/ unionfs /" would not work (because of recursion).


It wouldn't recurse (the unions are built from what exists at mount time, not from what results from it), but you'd run into problems like with files being already open and becoming shadowed by the mount (to name one of the problems). While the running app would still read and write from/to the old location, all later opens would access the new one.

This could be solved by mounting at a very early stage (as Knoppix does). However, especially with software updates from Nokia, this could cause more grief than what you'd gain from it, so I (I'm the one who wrote it) decided to suggest using it for subtrees of the root FS only.