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Re: GVP Combo board, serial port, etc...

On Sun, 9 Jun 1996 01:05:51 -0500 (CDT),
YU SONG <cs_yus%cs4.lamar.edu@localhost> wrote about Re: GVP Combo board, 
serial port,
: On Sat, 8 Jun 1996, Michele Lucini wrote:
: > Hi!
: >I'm running NetBSD 1.1 on an A3000 & an A2000 equipped with a GVP Combo 
: >board ('030, 22MHz).
: >On the A3000 everything works very nicely, but not on the A2000.
: >The two computers are connected together with a SLIP connection. Now, 
: >the problem is that on the A2000 I keep getting a lot of silo overflows.
: >Yes, I recompiled the kernel with the level_6_defer option, but it 
: >doesn't help. I think that in some way the DMA access of the SCSI 
: >controller on the GVP board should be disabled, or limited to smaller 
: >blocks. I have the same serial problems even under AmyOS, I had to use a 
: >patch to split the size of DMA transfers.
: >Can anyone tell me what options should I add to my config file? Or even 
: >better, it would be nice if somebody can e-mail me a config file that 
: >generates a nicely working kernel for GVP boards.
: Add "options "SERIBUF_SIZE=8192" " in your configuration file and recompile.

Adding extra serial buffers in software will not help - this is a hardware
problem, caused by the SCSI device driver mastering the bus for too long
during DMA transfers. There may be some utility available to split the DMA
transfers into smaller blocks (a la GVPPatch for AmigaOS), but in my
experience this does not help much anyway.

There are two real options available - buy the Guru ROM, a replacement for the 
Series II ROM, or buy a "real" serial card. The two are approximately the same
in price; I'd go for the latter.

-- Mat.

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