#40 atari_scsi module hangs as of Linux v4.5-rc1 because of emulator bug (patch is available)

[Finn Thain]

Figure 3.2 in the datasheet for the Nat. Semi. DP5380 (SCSI Bus Controller) says that there are three read-write registers. These are the Initiator Command Register, Mode Register and Target Command Register.

Unfortunately, Aranym's emulated 5380 device implements all the chip registers as write-only. When read, they return zero or a constant. This causes the Linux atari_scsi module to hang as of Linux v4.5-rc1.
http://lkml.iu.edu/hypermail/linux/kernel/1601.3/00037.html

Linux v4.5-rc1 contains bug fixes for the 5380 driver. These fixes require working device registers.
A patch to fix the Mode Register and allow Linux v4.5-rc to boot is available here:
http://article.gmane.org/gmane.linux.ports.m68k/8220/raw

This patch has been tested with Linux. I expect it will also support other operating systems, if those operating systems are compatible with a real L5380 chip.