4 ms·
No, I mean we were sending invalid command sequences to the XHCI controller, and as a result it wasn't sending anything to the ports at all.
by waddlesplash 8y ago
No, I mean we were sending invalid command sequences to the XHCI controller, and as a result it wasn't sending anything to the ports at all.
- nitrogen 8y agoThere are probably ways of dumping PCI writes; I'm curious if any tracing of that sort was used (comparing traces to known working OSes), or if it was all about comparing code to the spec.
- jclulow 8y agoWe've gone through similar rounds of debugging our XHCI bits on illumos. PCI and USB sniffing hardware is expensive and we have access to neither. You can get a long way by becoming comfortable with the specification, reading and getting review on your source, and by using the debugging tools on your OS (we have MDB and DTrace, etc).
- userbinator 8y agoUsing a VM is another way --- a virtual USB controller can log how it's being manipulated.