Progress w/ UDF Filesystem Support in 2.4.0?

LionMage asks: "I know Slashdot covered this a long time ago, but we have a new kernel now, and other things have changed as well. I followed the evolution of the experimental UDF drivers back in the 2.2.x series of Linux kernels, and Ben Fennema seemed to have both read and write support working. He claimed to be able to write to a CD-RW in UDF format, and I tried his drivers with my DVD-RAM drive with some measure of success. Recently, I installed SuSE Linux 7.1 on my machine, and discovered that the DVD-RAM drive was detected as two different devices, a CD-ROM drive and a "CD writer." OK, well, we'll forgive that little transgression. What's interesting is that inserting a DVD-RAM cartridge with data on it will in fact yield positive results when mounted. So clearly, the 2.4.0 kernel has some UDF support in it. (Unless this is a case where SuSE threw in support on a whim.) But I can only mount UDF volumes read-only. What's the point of a DVD-RAM drive under Linux if you can't write to it? A visit to Ben's page showed that little progress has been made recently, and there are no patches for the 2.4 series kernels. Can anyone comment on UDF support in the current Linux kernel, and how it's progressing? Alternately, are there perhaps some other drivers I'm unaware of which allow write support?"

Advantage of Open Source

[Prisoner 655321]

This is where the strength of open source will show because I'm sure now that a new kernel is out, it won't be long before the UDF drivers are completed. The write-only is probably just in the making (though i have no evidence). You also can't expect it the next day either, give a couple more weeks and hopefully there will be results.

UDF yes but DVD vob no

[johnjones]

UDF read/write is cool but VOB files are not comeing any time soon regards john jones

Packet writing

[TheMutantPenguin]

UDF write support is available as an option in the kernel (EXPERIMENTAL and DANGEROUS) if you had noticed that you can compile kernels yourself also.

What's really needed for UDF CD-RW and DVD-RAM write support is packet writing. That allows you to write data to the disk in little packets instead of a big stream, so you can write files at a time. Problem is, it's not in the kernel yet; Jens Axboe has a relatively old patch for a 2.4.0-test kernel that I gave up trying to apply to even 2.4.0. When fully implemented, packet writing will allow you to mount -w /dev/cdroms/cdrom0 (or the equivalent packet device if it is implemented using a separate device) /cdrom and then work with files on the CD-RW just like normal files -- with reading and writing. Fun? Go yell at people and it'll get implemented.

Why you got a CDROM and CDR for the same device

[Nailer]

You have an ATAPI IDE CDROM writer. ATAPI uses a SCSI like command set over an IDE bus.

The `CD ROM' is /dev/hdx, the IDE device for your CD writer

The `CD writer' is /dev/scdx, the SCSI device for your writer.

UDF and DVD ioctl support is is Linux 2.2.16 or 2.40 or newer. There's some serious bugs in 2.4.1 which mean you`ll want to avoid that particular version.

Since iso9660 bears a similarity to UDF, you can actually mount many DVDs using this driver, but they'll fail when ISO9660 does - after 2 gig.

Re:hi

[Anonymous Coward]

Hi. I'm Al Gore. I demand a recount.

Hey... I know you! You're the guy that invented pants!

Re:Packet writing works with DVD-RAM

[ivan256]

Packet writing in 2.2.17+ and 2.4.0+ works just fine with no special patches. Just mount away read-write (as long as you built your kernel with read-write support). Though it is marked experimental and dangerous, I haven't had any trouble with the two drives I have here. You can also use any file system you wish. It doesn't have to be UDF. It doesn't work with CD-RW yet though.

BTW, if you want to create UDF filesystems, you need the UDF utilities which you can get from http://freshmeat.net/projects/udf/ [freshmeat.net]

Re:Packet writing works with DVD-RAM

[Ben Fennema]

Packet writing is only needed for CD-RW drives. With DVD-RAM, you can just write away. There were some patches for 2.2 which made the DVD-RAM drive show up as 2 devices. 1 was a cdrom, and 1 was a harddisk. In 2.4, support was added for writing to the cdrom driver, so it should only show up as one device, but it should be writeable (at least thats how I understand things should work).

Ben

UDF status

[Ben Fennema]

Ok, here's whats up =)

2.4.X includes both read/write support for UDF based on the 0.8.9.X release.

The latest version is 0.9.3. The 0.9 series made some major write changes, which is why I havn't sent a diff off to Linus.

If you want to use UDF, I'd suggest grabbing the cvs source off of sourceforge and just compiling it as a module. (linux-udf project)

For DVD-RAM, as long as you compile UDF with write support, you should be able to mount it and write to it (after making the filesystem on it - or using a disc with a pre-existing filesystem on it).

For CD-RW, you need packet writing support. I recently gave a shot at porting pktcdvd from Jens Axboe to 2.4.2 and I got it working, but its not especially stable. =) For information on pktcdvd check out the packet-cd project on sourceforge.

Ben