james@bigtex.cactus.org (James Van Artsdalen) (01/02/91)
In <507@zok.UUCP>, mark@zok.UUCP (Mark W. Snitily) wrote: > Evidently the new 2.2 release enables instruction pipelining in the > 386 processor, something which ISC neglected to tell us poor souls. I was not aware that instruction pipelining was under software control. How is this done? Do you refer to the LE and GE bits of DR7? > Check your 386 processor, just below the i386 logo should be the > processor version. If the chip is the SX211 version, you're in > trouble because there is a bug in processor regarding instruction > pipelining [...] That line does indeed tell the stepping of the processor (the date code is on the bottom of the chip). But it is not a one to one mapping: a given stepping may have several SXnnn codes. However, I do not believe that you are necessarily in trouble with an SX211 chip. My memory may be wrong, but I think that the instruction pre-fetch bugs required address pipelining (and paging, and a TLB miss, and #NA asserted, and a full moon...). One would hope that the board designer took this into account and didn't use pipelining in situations where it didn't work. > The solution is to replace the chip with the "SX219" version, the hang > problem will vanish completely. Word of caution: if the system is designed for the SX211, it may not have fixes for bugs in the SX219. Changing CPU steppings can cause problems. > I advise everyone to check their processor version before upgrading or > purchasing 2.2, this problem will most likely affect *any* machine with > the SX211 version chip. Again, this is not correct in all cases. It's entirely possible that work-arounds for the errata are on the motherboard, in which case an SX-211 might work just fine (and an SX-219 might not work at all). 33MHz parts and 25MHz parts have different SXnnn codes, even if they're otherwise the same. -- James R. Van Artsdalen james@bigtex.cactus.org "Live Free or Die" Dell Computer Co 9505 Arboretum Blvd Austin TX 78759 512-338-8789
mark@zok.UUCP (Mark W. Snitily) (01/02/91)
In article <52096@bigtex.cactus.org> james@bigtex.cactus.org (James Van Artsdalen) writes: >In <507@zok.UUCP>, mark@zok.UUCP (Mark W. Snitily) wrote: > [Stuff about replacing a 80386/33 rev SX211 with a rev SX219 to fix ISC 2.2 upgrade problems.] James's followup listed many good points. Just wanted to clarify that I was quoting from an old posting (July '90) made by Arthur W. Neilson III. Arthur's signature is/was: Arthur W. Neilson III | ARPA: art@pilikia.pegasus.com Bank of Hawaii Tech Support | UUCP: uunet!ucsd!nosc!pegasus!pilikia!art Questions should be directed to Arthur, not me. Happy New Year. -- Mark Mark W. Snitily Consulting Services: 894 Brookgrove Lane Graphics, Operating Systems, Compilers Cupertino, CA 95014 (408) 252-0456 mark@zok.uucp West Coast UUCP X11 archive site If your mailer doesn't like the .uucp domain, these also work: ...!{mips,sgi}!zok!mark, mark%zok@mips.com, mark%zok@sgi.com For an interesting symmetry, compare the 1661 and 1991 calendars.