faq

这是Linux系统下的对UDF文件系统新增的功能

UDF Filesystem FAQ (Frequently Asked Questions)
Version 0.3 2/10/2002

1.1) What versions of Linux are supported?
	2.0 Not supported
	2.2 All versions
	2.4 All versions include this driver
	2.5 All versions include this driver
	
2.1) Can I play DVD Roms with this driver?
No, this is a filesystem driver. It lets you mount the disc, and see the files.  That won't be enough to play DVD movies, since they use an encrypted format.

2.2) Can I mount Video CDs with this driver?
No, that's a different beast altogether. However, there's an application called "MpegTV Player" that works. You can find it on http://freshmeat.net/.
	
2.3) Can I read DirectCD (or other packet-writing software) discs with this driver?
Yes, you should be able to (assuming the discs are closed).

2.4) Can I write to CDR or CDRW discs with this driver?
This UDF driver has support for writing to UDF filesystems, but only to non-CDROMs, such as hard drive partitions or loop-back filesystems.

As of this writing, the Linux kernel doesn't support writing to writable CDROMs of any kind - it assumes a CDROM is read only at a low level, which isn't easy to work around. Work is under way to fix this. In the meantime, when you mount a writable CDROM (either CDR or CDRW), you will get a notice saying "block device is write-protected, mounting read-only", even if you specify the "-o rw" option.

For "Alpha" support for writing to CDRW's only (2.4+ only), ftp to:
http://w1.894.telia.com/~u89404340/patches/packet/ or
ftp.kernel.org/pub/linux/kernel/people/axboe/packet/ for older versions.


cdrwtool (used to blank/format media) and pktcdvd (needed for mapping the packet
write driver to the cdrom device) are included in udftools.

NOTE: Neither the pktcdvd driver nor the current UDF version support recovering
from a failed packet write, so do not use this to write mission critical data
to CDRW's.

3.1) How come DirectCD file names appear normal in Windows 95/NT, but in all capitals on Linux?
This Linux driver displays the name as it appears on the disc, within the UDF specification.

Windows 95/98/NT writes files in all caps unless the file is other than 8.3, and you haven't specifically named it with varied capitalization. It does this to optimize it's VFAT directories, and Explorer displays the names with only the initial letter capitalized. 

3.2) How come some discs can be read in DirectCD, but not with this driver?
Usually, these are discs that DirectCD (or other packet-writing software) has not 'closed', ie, finished writing the UDF volume information. Some of these discs will cause the kernel to crash in the lower-level driver, even if the UDF driver isn't loaded. More work needs to be done to understand this problem.

If a disc is open, it might be possible to read it using the pktcdvd driver
(see 2.4) as it uses newer functions for determining the last block on a disc.
(Be sure to mount ro)

3.3) So, is there any way to write CDROMs in Linux?
Yes, the "cdrecord" application can write to CDROMs. You can find it on freshmeat.net, http://freshmeat.net/appindex/1998/03/13/889803174.html.  Although it can write with any filesystem, the 'mkudf' program included with the driver in the tools subdirectory hasn't been completed.
	
3.4) Ok, so how come "cdrecord" can write and UDF can't?
The cdrecord software uses the "generic scsi" interface, which isn't something you'd want to use in a filesystem driver. Not that's it's impossible, just difficult.  We'd rather work with the cdrom maintainers to update Linux's support for CDR/CDRW.