Win CE memory pages

I am looking into the workings of memory pages within the CE
environment. I am currently doing my investigations on an iPAQ PDA,
PPC2003, use PB4 and EVC4 (but I don't think this is a device specific
issue).

My question is, how come if I remove some memory pages with the
GetKPhys() function then do a soft reset of the device, the pages are
available again?

Looking though physmem.c (in PB4) then it seems that the page links are
zeroed and the pUseMap set to be used when this function is called. I
would have thought that on a reboot (after the soft reset) the OS
wouldn't be able to see these pages (until a hard reset happened).

Could anyone please fill in my knowledge gap here please.

Thanks in advance

Steve
Thu Mar 09 08:44:27 CST 2006

At boot time the system always clears and initializes all MMU table entries.
Why would you think that any of that would remain after a reset?

--
Steve Maillet
EmbeddedFusion
www.EmbeddedFusion.com
smaillet at EmbeddedFusion dot com

Andy
Thu Mar 09 09:13:50 CST 2006

Thanks for the rapid reply.

I just thought that would only happen on a hard reset. I thought that
if, for example, the system wanted to store some info in RAM while a
soft reset happened then this may be how it was done.


Steve Maillet (eMVP) wrote:
> At boot time the system always clears and initializes all MMU table entries.
> Why would you think that any of that would remain after a reset?
>
> --
> Steve Maillet
> EmbeddedFusion
> www.EmbeddedFusion.com
> smaillet at EmbeddedFusion dot com

Steve
Thu Mar 09 09:45:51 CST 2006

It doesn't need to keep the MMU mapping to retain data across a reset. It
just needs to make sure the RAM controller stays active during the reset.
The virtual mapping is re-initialized every time.

--
Steve Maillet
EmbeddedFusion
www.EmbeddedFusion.com
smaillet at EmbeddedFusion dot com