Scott A McConnell (samcconn@cotw.com) writes: > I have been trying to track down and resolve a spurious interrupt > problem. I have attached some output and the code used to generate it in > i8259.c. Part of your problem may be write buffer hell. Whatever you do to clear the interrupt when you've done with it involves writing to the 8259 controller. It's probably a long way away - probably through a PCI bus to a simulated ISA bus. Somewhere along the line the writes will be 'posted'; your CPU is fast, so when your CPU emerges from its interrupt routine the write may not have reached the 8259 yet, and you'll get a spurious interrupt. The code which switches off the interrupt at the 8259 should probably be equipped with a 'barrier' call to some system function which waits until the write has really happened. Then 8259s are ugly things which have some very CPU-specific interactions with x86 CPUs. In a non-x86 context you need to initialise them in particular ways. -- Dominic Sweetman Algorithmics Ltd The Fruit Farm, Ely Road, Chittering, CAMBS CB5 9PH, ENGLAND phone +44 1223 706200/fax +44 1223 706250/direct +44 1223 706205 http://www.algor.co.uk
