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BSP Memory Clear?

On Fri, 30 Apr 1999, Jake Janovetz wrote:

>    This may be one of the messages that ended up in the 
> oarcorp blackhole, I can't remember.  I have an application
> where it would be nice to boot up as quickly as possible.
> Unfortunately, clearing my 16 meg of RAM takes several 
> seconds.
>    Is there any reason that I need to clear all the RAM?
> Or, can this step be eliminated?

RTEMS assumes the executive workspace is zeroed at boot.  You may be
clearing this twice in your start code and in RTEMS if
do_zero_of_workspace is set to TRUE in the CPU_Table.  See
http://www.OARCorp.com/rtems/standardsupport/source/snapshots/doc/html/support/c_m68k/a00038.html
for details.

The other part of memory to possibly clear is the malloc heap.  If you set
do_zero_of_workspace to TRUE, then this area will be zeroed also.  Code
ported from UNIX often assumes memory allocated from theheap at program
startup is zeroed.  

So .. you could be clearing the memory twice.

Also .. it is quicker to clear memory 4 bytes at a time so if you have a
byte-wide loop, go to a word based loop.

--joel
Joel Sherrill                    Director of Research & Development
joel at OARcorp.com                 On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
   Support Available             (256) 722-9985