<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>Things to know about uio_pci_generic</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="The Userspace I/O HOWTO"><link rel="up" href="uio_pci_generic.html" title="Chapter 5. Generic PCI UIO driver"><link rel="prev" href="uio_pci_generic.html" title="Chapter 5. Generic PCI UIO driver"><link rel="next" href="uio_pci_generic_userspace.html" title="Writing userspace driver using uio_pci_generic"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Things to know about uio_pci_generic</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="uio_pci_generic.html">Prev</a> </td><th width="60%" align="center">Chapter 5. Generic PCI UIO driver</th><td width="20%" align="right"> <a accesskey="n" href="uio_pci_generic_userspace.html">Next</a></td></tr></table><hr></div><div class="sect1"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="uio_pci_generic_internals"></a>Things to know about uio_pci_generic</h2></div></div></div><p> Interrupts are handled using the Interrupt Disable bit in the PCI command register and Interrupt Status bit in the PCI status register. All devices compliant to PCI 2.3 (circa 2002) and all compliant PCI Express devices should support these bits. uio_pci_generic detects this support, and won't bind to devices which do not support the Interrupt Disable Bit in the command register. </p><p> On each interrupt, uio_pci_generic sets the Interrupt Disable bit. This prevents the device from generating further interrupts until the bit is cleared. The userspace driver should clear this bit before blocking and waiting for more interrupts. </p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="uio_pci_generic.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="uio_pci_generic.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="uio_pci_generic_userspace.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 5. Generic PCI UIO driver </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Writing userspace driver using uio_pci_generic</td></tr></table></div></body></html>
