Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Wed, 14 Apr 2004 11:14:33 -0500

Dirk Zimoch wrote:

The delay is *before* anything happens on the network:
-> reboot
[30 seconds delay]
Press any key to stop auto-boot...
 0
auto-booting...
[all the boot parameters printed here]
Attached TCP/IP interface to fei0. [no delay here!]
Attaching network interface lo0... done.
Loading... 1461088
Starting at 0x100000...
[30 seconds delay]
Attached TCP/IP interface to fei unit 0 [no delay here!]
Attaching network interface lo0... done.

How much RAM do you have on this board, and how much VME space are you
mapping for CPU access? It can take vxWorks quite a long time (and RAM)
to create all of the MMU's Page Table Entries (PTEs) for the memory and
VME areas listed in your sysPhysMemDesc[] table, especially if you're
mapping in a large amount of VME A32 space. That PTEs get created twice
during the boot sequence at exactly the points you mention having a delay.
RAM usage for PTEs is I believe a ratio of 1/128 (i.e. a 128MB mapping
needs 1MB for PTEs), but that ratio varies between CPU families.
I use the PPC's BAT registers to map in the A32 space, which is much
faster than creating PTEs but it does limit you to only 1GB because there
are only 4 DBAT registers with a maximum mapping size of 256MB. Of course
if you have more RAM than you need for A32 space then it might make more
sense to swap the two and use PTEs for A32 and BATs for RAM, but if you
try that be aware there may be complications in doing so.
If you have much more RAM than you need, you could also turn off the
vxWorks auto-memory sizing and just don't use it all, which will speed up
the PTE creation time.
- Andrew
--
Dear God, I didn't think orange went with purple until I saw
the sunset you made last night.  That was really cool. - Caro

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System