By default and design, Alta PCIe-based products use the MSI (Message Signal Interrupt) mechanism for hardware interrupts. This works well in most applications. But, when it is required to have multiple applications opening and controlling independent channels on an Alta PCIe device AND each of these is required to use hardware interrupts, this will not work.
This is because the driver hooks to initialize each interrupt MSI space separately and independently does not exist. If separate applications attempt initializing separate channels to use MSI interrupts, the system will lock up or will reboot.
Using legacy interrupts avoids this and enables separate applications to use interrupts on separate channels.
The How-To document Alta-PCIe-How-to-Use-Legacy-Interrupts.pdf (78 downloads ) explains how to convert the inf files for your PCIe device to use legacy interrupts.
