Hi

reading about terminal server sizing I recognized the term "system page table entries" quite often. Unfortunaltey

I understand the 4 GB virtual memory is devided into 2 GB users space (a private space for each process) and a 2 GB system space. Page table entries are used to map virtual memory addresses to physical ones.

From my understanding, system page table entries are used to map the complete 2 GB system space to physical memory and normal PTEs describe the users space. I heard SPTEs are a limited resource and the OS is not able to use the complete 2 GB space due to this limitation

If I'm wrong and SPTEs describe only portions of the system space, which portions are described? Why isn't it possible to use just PTEs

I appreciate your help
Stephan

Re: Question about system page table entries by Maxim

Maxim
Thu Apr 29 05:33:31 CDT 2004

> If I'm wrong and SPTEs describe only portions of the system space, which
portions are
>described? Why isn't it possible to use just PTEs?

SPTEs are ones that describe around 128M (or such) at 0xe0000000 or such.

MmMapIoSpace uses it, MmGetSystemAddressForMdlSafe also uses it.

--
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
maxim@storagecraft.com
http://www.storagecraft.com



Re: Question about system page table entries by anonymous

anonymous
Fri Apr 30 04:01:04 CDT 2004

Thank you for your reply. Now it's getting clearer

- Stephan

Re: Question about system page table entries by Maxim

Maxim
Fri Apr 30 07:13:43 CDT 2004

NOTE:

- MmAllocateMappingAddress is a low-level primitive which just allocates
SPTEs.
- MmMapLockedPagesWithReservedMapping then updates these PTEs to point to
the necessary physical pages.
- MmGetSystemAddressForMdlSafe is a combination of them both.

--
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
maxim@storagecraft.com
http://www.storagecraft.com


"Stephan Perschke" <anonymous@discussions.microsoft.com> wrote in message
news:0DA98248-8F9B-4C4B-826F-8BBAC9D1D83D@microsoft.com...
> Thank you for your reply. Now it's getting clearer.
>
> - Stephan