Steps to reproduce the problem:
- Compile a kernel with scsi.
- Load aha1542 and sr_mod.
- Mount a CD-ROM.
-> SCSI DMA out-of-memory, disabling scatter-gather, ...
- Compile a kernel with scsi and aha1242.
- Load sr_mod.
- Mount the same CD-ROM.
-> No problem at all.
Right now I don't know where to look further. :-/
-- An economist is an expert who can tell you tomorrow why his prediction of yesterday didn't come true today.-- Matthias Urlichs