Subject: Re: Problem with serial I/O with GVP
To: Max Leung <mleung@ee.ualberta.ca>
From: Chris Hopps <chopps@emunix.emich.edu>
List: amiga-dev
Date: 04/01/1994 10:27:28
> 
> 
> 
> On Mon, 28 Mar 1994, Max Leung wrote:
> 
> > I installed the latest generic kernal (vmunix.generic.940325), and now 
> > find that whenever there is disk activity, serial I/O gets mangled!
> > 
> > This never happened with the 744 kernel (with DMA off).
> > 
> > When I turn off DMA, the serial I/O doesn't get mangled as much. With DMA 
> > enabled, I get download errors every 4 or 5 K. Seems like when rz flushes 
> > the data to disk, the corresponding disk I/O corrupts the serial line.
> > 
> > This sounds like the infamous GVP-controller-trashes-serial-I/O-because-its-
> > priority-is-too-high bug I've seen on the AmigaDOS side.
> > 
> > Is there a way I can fix this, without recompiling the kernal?
> > 
> > (I have an old GVP-Combo, 22 MHz, 13 megs of 32bit RAM, in an A2000 with 
> > 1 meg chip. The only other board I have in it is the A2232 serial I/O 
> > board, which does nothing under NetBSD. :-) )
> 
> I tried turning off everything, including setting _gvp11_dmamask to 4K 
> (instead of 64K), turning off the gvp bounce buffer, and turning of scsi 
> dma, but I still have serial I/O problems? Is there a fix?
> 
> Please help! I haven't got a response to the above message. I'm wondering 
> if anyone is receiving it...
> 
> I'd really like to get serial transfers to work. Otherwise, I can't use 
> Term nor can I use my Amiga as an X server for remote clients!
> 
> > 
> > Thanks,
> > Max Leung
> > 
> > ---------------------
> > mleung@ee.ualberta.ca
> > 
> 
> 


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