Appendix A Need More Slots; Multiple Pcie Expansion System Configurations - Magma EB4-1U User Manual

Appendix A Need More Slots?

Multiple PCIe Expansion System Configurations

The PCIe Local Bus Specification defines the PCIe bus as a hierarchical
bus, where PCIe to PCIe Bridges (PPBs) may be used to add "levels" to
the PCIe bus hierarchy. Because hierarchies are organized systems
arranged into different levels, you can take advantage of this automatic
organizing and layering to expand the number of available PCIe slots
beyond the number available in your computer's motherboard.
You can easily add two or more Magma expansion systems to your
current system in either a "fan-out" or "daisy-chain" configuration. Each
of these configurations has advantages and uses. To determine which
type of configuration you wish to use, you should first understand a few
basic facts:
1. In a desktop computer, the bios enumerates automatically
behind PCIe bridges. In the Magma configuration, the bios
finds the Magma host card in a PCI Express slot. The bios
configures it, and then looks beyond it to find any PCIe cards
installed in the expansion chassis. The bios then configures
the cards and allocates resources. Empty PCIe slots are
ignored during configuration.
In theory, your computer "should" be able to travel across up to
255 PCIe buses to identify and configure all installed PCIe
cards. Unfortunately, not all computers are created equal. The
255 PCIe bus limit is actually a theoretical maximum. The
practical limit is somewhat lower, but should still be a fairly large
number.
In a desktop computer the bus numbers tend to be lower (0, 1,
2, etc.). Once the bios is finished configuring everything and
assigning resources, the Operating System starts loading and
activates the PCIe cards found.
When adding more Expansion Systems to an existing system,
be sure to connect and test them "one-at-a-time." This will allow
you to quickly resolve any connectivity, or other, issues right at
the start. DO NOT INSTALL any 3
system until ALL attached systems are working correctly.
rd
Party PCIe cards into any
Appendix B Need More Slots?
M A G M A
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