DOCUMENT:Q159536 31-JAN-2001 [win95x] TITLE :PCI Device Using Prefetchable Memory Generates Code 15 PRODUCT :Microsoft Windows 95.x Retail Product PROD/VER::2,2.1 OPER/SYS: KEYWORDS:osr2 win95 ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Windows 95 OEM Service Release, versions 2, 2.1 ------------------------------------------------------------------------------- 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 ====================================================================== Keywords : osr2 win95 Technology : kbWin95search kbOPKSearch kbWin95OPKOSR2 kbWin95OPKOSR210 Version : :2,2.1 ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2001.