Q159536: PCI Device Using Prefetchable Memory Generates Code 15
Article: Q159536
Product(s): Microsoft Windows 95.x Retail Product
Version(s): 2,2.1
Operating System(s):
Keyword(s): osr2 win95
Last Modified: 31-JAN-2001
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The information in this article applies to:
- Microsoft Windows 95 OEM Service Release, versions 2, 2.1
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SYMPTOMS
========
When you have a PCI device installed behind a PCI-to-PCI bridge, it may be
listed in Device Manager with an exclamation point in a yellow circle. The
status for the device on the General tab may report Code 15, indicating a
resource conflict.
CAUSE
=====
The computer's BIOS may not support the memory addressing needed to use the
device in its current slot. For some PCI slots, BIOS support for Prefetchable
Memory Addressing is required.
RESOLUTION
==========
Contact the computer's manufacturer to obtain a BIOS update that supports
Prefetchable Memory Addressing for devices on the PCI-to-PCI bridge.
You may also be able to resolve the problem by moving the peripheral device to a
slot that is not behind a PCI-to-PCI bridge.
MORE INFORMATION
================
Prefetching addresses the problem of increasing memory latency relative to the
CPU core speed. Beyond data caching, data prefetching is an effective way to
address the memory access bottleneck associated with high- performance
processors. This is particularly true for programs whose working sets cannot be
easily fit into the on-chip data cache (the L1 cache).
The prefetching cache uses a technique for hiding memory latency by exploiting
the overlap of processor computations with data accesses. A prefetching cache
generates prefetch requests to bring data into the cache before it is actually
needed, allowing overlap with pre-miss computations.
The prefetchable memory is speculative. However, devices that are designed to
take advantage of prefetching can increase performance by reducing misses. A
device that supports prefetchable memory marks data with a bit as either
suitable or unsafe for prefetching. A BIOS not written to take advantage of this
feature may experience problems with the configuration of the device.
Additional query words: 95
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Keywords : osr2 win95
Technology : kbWin95search kbOPKSearch kbWin95OPKOSR2 kbWin95OPKOSR210
Version : :2,2.1
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