On 5/7/25 10:06 PM, Phil Pemberton wrote: > It's me again, with another weird IDE device.. > > The device is a Panasonic PD/CD-ROM drive. Under Windows it enumerates as two > drives, apparently LUN 0 and LUN 1. LUN 0 is a CD-ROM, and LUN 1 is the PD-RW > block device. > > (PD is Phase-change Dual, a rewritable optical disc format developed by > Panasonic in the 1990s, it stores 650MB on a CD-sized disc encased in a DVD- > RAM-like caddy) > > Unfortunately Linux 6.12.9 (on Debian Bookworm) only detects the first LUN, the > CD drive. If a PD disk is inserted into the drive then there's no way to read it. > > It seems like the Linux ATAPI layer only supports a single LUN. Is there a way > to extend it to support the second LUN on the Panasonic drive? Is this a new issue with 6.12.9 or was it working before ? There is no concept of Logical unit/LUN in ATA/ATAPI. That simply does not exist at all. Likely, Windows has a special driver for that second PD drive and exposes both drives as 2 LUNs of the same device. Unless that PD drive thinggy uses a standard ATA/ATAPI interface, I do not see how to make this work. But just in case, please share an output of dmesg for this system probe of the AHCI adapter and ATA/ATAPI devices so that we can see what's going on. And please CC the maintainers when sending emails to a Linux kernel mailing list. Otherwise, your email will likely be lost/ignored. -- Damien Le Moal Western Digital Research
