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Re: Memory Allocation !!


in my experience, some older BIOSes haveproblems if more than 256Mb are
requested by single bus segment.

On the OS side, there may be troubles mapping device memory to virtual
addresses. PCI memory is always mapped to non-paged virtual addresses and
the OS needs to support a sufficient number of PTEs (Page table entries). On
WinNT, e.g., non-page pool in kernel mode is limited to 192MB. Non paged
pool is used for all PCI memory on that machine and partially for memory
allocated by the driver (buffers, device objects, driver objects, etc.).


Peter Marek
General Director
MarekMicro GmbH
tel.: 049-9621-9732-110
fax: 049-9621-9732-199

----- Original Message -----
From: "Amit Shah" <ashah10@agere.com>
To: <pci-sig@znyx.com>
Sent: Thursday, October 11, 2001 5:40 PM
Subject: Memory Allocation !!

> Hi Experts,
> I am working on a chipset which requires near about 32MByte of memory
> allocation through one of the BAR's.
> And on our system you can have multiple  of these chipset on the same
> PCI bus.
> Have anyone of you encountered problems with allocation of multiple
> large memory maps on  a PCI system ?
> Can OS handle such large allocations ?
> If not, how do we solve this issue on a system level or OS level.
> (We support a wide range of OS).
> Thanks,
> Amit Shah
> Agere Systems