Re: scsi freezing problem with NetBSD current

[David Brownlee <abs%NetBSD.org@localhost>]

j>> On Tue, 28 Oct 2008, David Ross wrote:
> > > My understanding was that a lot of DMA on the TT030 is to ST-ram, but the 
> > > SCSI DMA specifically does use TT-ram.  Doing some quick digging, I found:
> > > http://www.vanc.igs.net/~roughley/overview.htm#SCSI
> > >
> > > Which says:
> > >
> > > "The TT's SCSI direct-memory-access subsystem can send and receive 
> > > information equally well, both from ST RAM and faster TT RAM, meaning that 
> > > present and future software will be able to exploit SCSI peripherals 
> > > efficiently."
> > >
> > > There's a great archive of TT030 hardware info that may be useful as well:
> > > http://dev-docs.atariforge.org/html/search.php?find=_4
> >
> >         There is a comment in sys/arch/atari/dev/atari5380.c:
> >
> >         /*
> >          * LWP: DMA transfers to TT-ram causes data to be garbled
> >          * without notice on some TT-mainboard revisions.
> >          * If programs generate mysterious Segmentations faults,
> >          * try enabling NO_TTRAM_DMA.
> >          */
> >
> >         So, NetBSD is not currently using SCSI DMA to TT-ram.


        David just pointed out that NetBSD doesn't actually enable
        NO_TTRAM_DMA by default, so my above comment is bogus (sorry
        'bout that). Most of the rest of my email probably still made
        sense :)


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