Verification of Ext Physical Memory beyond 512MB

[Johan]

Hi All,

I read from several articles expecially from Sue Loh, that we are able
to extend the physical memory of WinCE 6.0 beyond 512MB using
VirtualAllocEx and VitualCopyEx. This is what i have done to replicate
it.

My Setup:
-WinCE 6.0 using CEPC with 1GB RAM

My Steps:
- Modify the sample stream driver where VirtualAllocEx and
VirtualCopyEx is called
- From an application, i will pass to the driver the application's
processID which VirtualAllocEx will use for reserving 512MB of space.
VirtualCopyEx is also called as shown.

In driver:
//processid is received from application
destprocess=OpenProcess(0,FALSE,processid);
sourceprocess=GetCurrentProcess();

p=(LPBYTE)VirtualAllocEx(destprocess, NULL, 0x20000000, MEM_RESERVE,
PAGE_READWRITE);
ret=VirtualCopyEx(destprocess, p, sourceprocess, (void*)0x20000000,
(512*1024*1024), PAGE_READWRITE|PAGE_PHYSICAL}PAGE_NOCACHE);

- With the returned base address of p, i am able to write and read
data into it in my application. (Which i assume that i have
successfully mapped the remaining 512MB of RAM left)
- However in my test to verify this, i purposely set the allocated
space to 512MB+1 byte. This should fail because i have only 1GB RAM.
The first half is taken by OS while only 512MB is left for mapping.
However, what i notice is that i am able to allocated the 512MB + 1
byte space and am still able to read and write to the last byte.

1) Why is this so? I though i only have up to 512MB of physical memory
left, why is that i am able to map more than 512MB and even access the
512MB + 1 byte ? (In the code, i am assuming that the remaining
physical memory i can map is from 0x20000000 to 0x3FFFFFFF)

2) Secondly, in my driver, i also include ability to free this mapping
via this codes

In driver:
//processid is received from application
destprocess=OpenProcess(0,FALSE,processid);
virtualFreeEx(destprocess,p,0,MEM_RESERVE);

When this code is executed, the whole CEPC restarts itselfs. Can i
know what i happening? Is there some kind of memory corruption that
caused this to happen?

Thanks for the help:)

[Johan]

Hi,

Any kind soul willing to help me with this? Thanks.

[Johan]

> Any kind soul willing to help me with this? Thanks.- Hide quoted text -
>
> - Show quoted text -

Can anyone pls take a look at my question and help me with this?
Thanks.