Arnd Bergmann wrote:
Am Mittwoch, 9. Januar 2002 02:51 schrieb Ben Fennema:
The only part of UDF that cares about the packet size is sparing, so you can run with whatever packet size you want (as long as the sparing tables are created correctly).. But it's very unlikely it would be cross platform. The spec allows the recording of packet size, but requires it to be 32 for CDRW media. (for fixed packets)
The scsi drivers (at least 2.4 and earlier) might also have problems with larger packets. It already breaks on controllers with sg_tablesize < 32 (e.g. aha1542 and a few more), but for 128 sector packets, it would break on many more of them (e.g. sym53c8xx) that then would have sg_tablesize < packet_size. OTOH, with 16 sector packets, it might work on the currently unsupported controllers. There are also drives that don't follow the standard exactly and give some undefined behaviour for anything that is not used by other OSs.
Excuse my ignorance (I'm not an expert on the block layer), but wouldn't it be possible to advertise pkt device as having blocks as large as the packet is? Or better, do this only for interfacing buffer-cache to let it have all the data in one chunk, and keep the fs interface 2kb based as the OSTA udf2.0 spec requires: udf2.0 par. 6.10.2.1: The host shall perform read/modify/write to enable the apparent writing of single 2K sectors.
Arnd <><
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