device: 0.775 socket: 0.654 other: 0.637 mistranslation: 0.616 vnc: 0.599 semantic: 0.548 network: 0.541 graphic: 0.536 boot: 0.454 KVM: 0.421 instruction: 0.351 assembly: 0.234 UHCI fails to signal stall response When TD execution results in STALL error (STALL handshake, no stall as a result of err count reaching 0), there is no way to know about it except for checking that TD. IMO it is an error condition and it should be reflected in the status register (and issue an interrupt if enabled). Ways to replicate: Send a query that is answered by stall (like set_idle request to a mouse) Expected behavior: UHCI hc sets status bit 1 (usb error interrupt) and issues an interrupt current behavior: Neither status bit is set nor interrupt triggered Version 0.14 attached patch for current master (quick fix, it might be I got something wrong) Hi, Thanks for reporting this issue. Just so you are aware: the qemu USB maintainer is probably going to be away for a while longer, so don't be too worried if this patch doesn't get looked at for 2-4 weeks. Brad No problem, it's not like it breaks something. This fix just makes driver development easier. On Thu, Apr 14, 2011 at 11:35 AM, jvesely