Subject: SCC silo overruns -- Re: X11 problems on 5000/133
To: None <port-pmax@NetBSD.ORG,>
From: Toru Nishimura <>
List: port-pmax
Date: 01/31/1998 12:49:07

In article <> wrote

>> I just installed 1.3 (binary using the generic kernel) on my 5000/133
>> (64M, PMAGB-BA, RZ25 disk) and was pleased at how simple it was using
>> the sysinst utility.
>>    [ .... ]
>> I noticed also that the kernel reports SCC silo overflows if
>> you move the mouse before X is started, is this normal?

Not normal.  It needs to be fixed, eventually.  If you do not mind
kernel build process, try follows and report the results to me;

In a file arch/pmax/tc/scc.c, function sccintr(), locate a if-clause;

	} else if (rr2 == SCC_RR2_A_RECV_DONE ||
                rr2 == SCC_RR2_B_RECV_DONE || rr2 == SCC_RR2_A_RECV_SPECIAL ||
                rr2 == SCC_RR2_B_RECV_SPECIAL) {
	else if (...

Insert lines enclosing the whole branch;

           do {
	   	....original if-clause body....
		SCC_READ_REG(regs, chan, SCC_RR0, cc);
	   } while (cc & ZSRR0_RX_READY);

Besides this NetBSD/pmax internal has deep deficiencies about how to
handle interrupt masks.  Jonathan could explain details.

Tohru Nishimura
Nara Institute of Science and Technology