PCI Device Using Prefetchable Memory Generates Code 15 (159536)
The information in this article applies to:
- Microsoft Windows 95 OEM Service Release 2
- Microsoft Windows 95 OEM Service Release 2.1
This article was previously published under Q159536 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.
| Modification Type: | Major | Last Reviewed: | 9/30/2003 |
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| Keywords: | KB159536 |
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