>> >I have just installed NetBSD-curretn i386 on a machine which has two scsi 
>> >controllers. The first is a Buslogic 445C VL-bus with two barracuda 
>> >drives. The second is an ADAPTEC-1542CF ISA card.
>> 
>> >Now that NetBSD has bounce-buffers everything should be fine but it 

>> Since when?  Did you apply an unsupported patch?  I haven't seen
>> anything announcing bus-master bounce buffers in the official NetBSD
>> distribution.

>For the ISA bus, which needs it if your machine has more than 16 Megs, 
>take a look at isadma.c. I don't think bounce buffers are needed for any 
>other bus, at least not for EISA nor PCI.

I think you misunderstand.  That code isn't for bus-master
controllers.  That is the code for using the motherboard DMA chips.
For things like the floppy controller, soundblasters and ethernet
cards.

This code does not affect bus-master devices like SCSI controllers
that do their own DMA from the cards own controller.  These don't yet
have bounce buffer support.  There is a very significant difference.

The code base required for the eventual adoption of a bounce buffer
implementation that will work on ISA busses on all architectures
(i386, DEC Alpha, Amiga, PowerPC, etc.) is slowly being incorporated.
Much of the work being done by CGD.  But, as far as I know, that work
is still far from complete.

>From what I understand, there is an unsupported patch floating around
that will patch a bounce-buffer that is i386-PC-specific into the 1542
driver.  But, it isn't supported since it wouldn't work on all
architectures, and because it is specific to the 1542.

I don't actually run any devices that require bounce buffers (well,
besides what's already covered by isadma.c), so I don't follow these
developments very closely.  Someone else please correct me if I'm
wrong on any of this.

-----------------------------------------------------------------------------
  Michael L. VanLoon                                 michaelv@HeadCandy.com
        --<  Free your mind and your machine -- NetBSD free un*x  >--
    NetBSD working ports: 386+PC, Mac 68k, Amiga, Atari 68k, HP300, Sun3,
        Sun4/4c/4m, DEC MIPS, DEC Alpha, PC532, VAX, MVME68k, arm32...
    NetBSD ports in progress: PICA, others...

   Roll your own Internet access -- Seattle People's Internet cooperative.
                  If you're in the Seattle area, ask me how.
-----------------------------------------------------------------------------