NetBSD master CVS tree commits

[source%NetBSD.ORG@localhost]

thorpej
Mon Sep 15 18:52:02 PDT 1997
Update of /cvsroot/src/sys/arch/alpha/alpha
In directory netbsd1:/var/slash-tmp/cvs-serv12217

Modified Files:
        locore.s pmap.old.c 
Log Message:
>From page 6-9 of "Alpha AXP Architecture Reference Manual, Second Edition":

        An IMB intruction must be executed after software or I/O devices
        write into the instruction stream or modify the instruction
        stream virtual address mapping, and before the new value is
        fetched as an instruction.

We were missing calls to IMB after mappings were changed, which caused
systems with large I-caches (e.g. my AlphaStation 500) to fail miserably
when mapping in new pages of program text, or when context switching
(I couldn't even get the shell from init!).