Physical memory mapping not used by OS

NTDEV
1

Hi,
There is a method of using phisical memory that is not used by the OS
via the MAXMEM switch. This may be done in order
to achieve non fragmented memory etc.

Are there any problematic issues with this concept and
Is it suitable for mapping a large amount of buffers ?

Can it handle the overlapping of PCI devices memory
with systems which has 4G ram installed ?

Thanks,
Tomer Goldberg

2

Tomer,

It is up to you to resolve the issue of any device memory mapped over
the physical memory
You also have to be very careful of memory mapped diplay hardware. I
suspect you will
need to scan registry info on all memory reserved or claimed by devices.
You can then map any of memory you want into your user space.

ned

Tomer Goldberg wrote:

Hi,
There is a method of using phisical memory that is not used by the OS
via the MAXMEM switch. This may be done in order
to achieve non fragmented memory etc.

Are there any problematic issues with this concept and
Is it suitable for mapping a large amount of buffers ?

Can it handle the overlapping of PCI devices memory
with systems which has 4G ram installed ?

Thanks,
Tomer Goldberg

Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256

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3

You’ll also have to figure out how to operate correctly in a machine where
somebody else’s driver pulled exactly the same hack.

–
Jake Oshins
Windows Kernel Group

This posting is provided “AS IS” with no warranties, and confers no rights.

“ned kacavenda” wrote in message
news:xxxxx@ntdev…
> Tomer,
>
> It is up to you to resolve the issue of any device memory mapped over the
> physical memory
> You also have to be very careful of memory mapped diplay hardware. I
> suspect you will
> need to scan registry info on all memory reserved or claimed by devices.
> You can then map any of memory you want into your user space.
>
> ned
>
>
>
> Tomer Goldberg wrote:
>
>> Hi,
>> There is a method of using phisical memory that is not used by the OS
>> via the MAXMEM switch. This may be done in order
>> to achieve non fragmented memory etc.
>> Are there any problematic issues with this concept and
>> Is it suitable for mapping a large amount of buffers ?
>> Can it handle the overlapping of PCI devices memory
>> with systems which has 4G ram installed ? Thanks,
>> Tomer Goldberg
>> —
>> Questions? First check the Kernel Driver FAQ at
>> http://www.osronline.com/article.cfm?id=256
>>
>> You are currently subscribed to ntdev as: xxxxx@colorts.com.au
>> To unsubscribe send a blank email to xxxxx@lists.osr.com
>
>
>
>

4

One can only follow the rules and hope that others do as well.
Unfortunately,
there is a ramdisk implementation out there that makes no attempt to
register
the fact that it uses a slab of memory.

Jake Oshins wrote:

You’ll also have to figure out how to operate correctly in a machine where
somebody else’s driver pulled exactly the same hack.