If you mean you want to write multisesion CDs in linux, then you are out of luck if you use a 2.4 kernel. That is the one thing that I have been unable to achieve using linux. I think udf support for linux is pretty flaky if at all present.
Well, UDF format & Multisession CDs are two different things all together. UDF format is used for CDRW discs where you can add/remove the contents as though it is a floppy disc using any file explorer. But for that purpose, the disc has to be "mounted" (with the UDF file system driver of the Packet Writing software) to be used. The packet writing software driver communicates with the OS whenever there is any WRITING operation happening on this mounted disc. It is "registerd" with the kernel as the "Event - handler" for write operation - I guess so.
Instead, Multisession CD is a normal CDR, where data is recorded at different times in "sessions". This can be done only in TRACK-AT-ONCE (TAO) mode.
But the problem with Multisession CDs is that not all the CDROM drives can read Multisession CDs. In fact, most CDROMs cannot. In contrast to the UDF writing, multisession CDs need not be mounted with special drivers. The filesystem is also the same as a normal CD -ISO9660. Whereas, the CDRW, when formatted with the packet writing software will have the filesystem as UDF (Universal Disk Format).
And this UDF writing in Linux is giving me problems. I could create all sorts of CDRs, but not a single CDRW in UDF format.
Kunal
PS : You can create Multisession CDs even with 2.4 tree kernels. I'm using 2.4.18-3 (RH 7.3).