SUMMARY 2: X errors and ZLXp-L2 Graphics card on AlphaStation 600 5/266.

From: Richard Bemrose <rb237_at_phy.cam.ac.uk>
Date: Wed, 28 Jan 1998 19:29:52 +0000 (GMT)

Hi again,

Following my original two post regarding X errors and AlphaStation 600
5/266 with ZLXp-L2 graphics card, I will summaries the general comments
and solutions! First of all, I must thank all those who contributed, in
particularly:

  Ib Koersner <koersner_at_tsl.uu.se>
  Knut Helleb <Knut.Hellebo_at_nho.hydro.com>
  Don Weyel <weyel_at_bme.unc.edu>
  Paul Watson <phwatso_at_cooper-energy-services.com>
  Robert L. McMillin <rlm_at_syseca-us.com>

Regarding the X errors from Networker Admin (nwadmin), this does not seem
to be an isolated incident as like errors also appear on an AlphaStation
1000 using a VGA graphics card (Cirrus Logic chip), as reported by Don
Weyel. Thanks to Robert L. McMillin we now understand why these error
messages occur and, more importantly, how to suppress such 'unaligned
access errors'. The errors are generated because (quoting from the man
page):

  "Most complete instruction set computers (CISC) can access unaligned
  data but only at a significantly reduced speed. Most reduced
  instruction set computers (RISC) do not attempt to handle unaligned
  accesses, but, instead, generate an "Unaligned Access Trap" and let the
  operating system handle the fault."

See 'man uac' for further details. To suppress these errors a flag can be
set on the REMOTE workstation:

  # uac s 0

Regarding the unscheduled termination of the display manager, our
particular problem has not been fully resolved. We do understand, however,
that Open3D is essential for our ZLXp-L2 graphics card. Knut Helleb
suggests inspection of the X server log file which is certainly useful:

  # more /var/dt/Xerrors

Furthermore, Paul Watson suggest to nice down the X server. On DU V4.0b,
this can be achieved by,

  # cp /usr/dt/config/Xservers /etc/dt/config/Xserver

and changing line,

:0 Local local_at_console /usr/bin/X11/X :0
to
:0 Local local_at_console /usr/bin/X11/X :0 -nice 2

Please note: the "-nice 2" options seems to be specific to DU V4.0b and
should read "-nice2" (no space) on DU V3.2.

I would dearly love to hear from any ZLXp-L2 graphics card users. Or any
other related information.

Regards,
Rich

 /_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/ _ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\
/_/ Richard A Bemrose /_\ Polymers and Colloids Group \_\
/_/ email: rb237_at_phy.cam.ac.uk /_\ Cavendish Laboratory \_\
/_/ Tel: +44 (0)1223 337 267 /_\ University of Cambridge \_\
/_/ Fax: +44 (0)1223 337 000 /_\ Madingley Road \_\
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 /_/_/_/_/_/_/ http://www.poco.phy.cam.ac.uk/~rb237 \_\_\_\_\_\_\
             "Life is everything and nothing all at once"
              -- Billy Corgan, Smashing Pumpkins
Received on Wed Jan 28 1998 - 20:37:38 NZDT

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