Autah-gr.334
net.unix-wizards
utzoo!decvax!duke!chico!harpo!utah-cs!utah-gr!thomas
Tue Mar 16 12:33:50 1982
Vax microcode bug
We just got this message from our FE.  Looks like it MIGHT explain the
microcode problem I asked about a little while ago.
=Spencer Thomas

	From MAINT@UTAH-20 Tue Mar 16 10:58:08 1982
	Date: 16 Mar 1982 0932-MST
	From: DEC Service-Tom <MAINT at UTAH-20>
	Subject: VAX MICROCODE
	To: FRANK
	Remailed-date: 16 Mar 1982 1044-MST
	Remailed-from: Randy Frank <FRANK at UTAH-20>
	Remailed-to: lepreau at UTAH-20, thomas at UTAH-20

	RANDY
	     VERSION 94 OF THE VAX MICROCODE, SHOULD TAKE CARE OF YOUR PROBLEMS.
	THE LIST IS TOO LONG TO LIST ENTIRELY, BUT OF MAIN CONCERN (I BELIEVE)
	IS PROBLEM 1, WHICH SAYS:
	"UNALIGNED MODIFY OPERANDS ACROSS PAGE BOUNDRIES"

	PROBLEM:  THIS BUG AFFECTS ANY INSTRUCTION THAT
	      1.  MODIFIES AN OPERAND, AND
	      2.  THE OPERAND IS UNALIGNED AND CROSSES A PAGE BOUNDRY, AND
	      3.  THERE IS A TRANSLATION BUFFER HIT FOR BOTH THE FIRST AND
	          SECOND PAGES, AND
	      4.  THE SECOND PAGE HAS NOT BEEN MODIFIED..... PTE<M>=0, AND
	      5.  AN INTERRUPT IS PENDING.


	THERE ARE SEVERAL MORE BUGS, BUT THIS IS THE |ONE THAT SOUNDS
	MOST LIKELY TO ME.
	I WILL SEE WHAT I CAN DO TO GET THE ECO AS SOON AS POSSIBLE.
	IT IS SUPPOSSED TO COME AUTOMATICALLY AS RELEASE 3 OF THE VAX.
	I WILL PUSH FOR SPEEDY DELIVERY
	                                TOM
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