[Bug 1103] New: Qemu gadgetfs needs to use asynchronous IO

[bugzilla-daemon at bugzilla.openmoko.org]

http://bugzilla.openmoko.org/cgi-bin/bugzilla/show_bug.cgi?id=1103

           Summary: Qemu gadgetfs needs to use asynchronous IO
           Product: OpenMoko
           Version: current svn head
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: enhancement
          Priority: P5
         Component: qemu-neo1973
        AssignedTo: balrogg at gmail.com
        ReportedBy: balrogg at gmail.com
                CC: buglog at lists.openmoko.org


Qemu currently uses blocking calls to talk to gadgetfs. Gadgetfs under linux is
poorly written and perhaps unused by anyone for a at least a couple of years
before we started using it in qemu, so it doesn't support any kind of polling.
As a result qemu sometimes blocks waiting for usbnet to respond on the host.
Another side effect is qemu relies on the blocking calls getting interrupted by
signals, which is ok when using "unix" clocksource but rules out "dynticks", so
currently I'm disabling dynticks every time usbgadget is used, it's a hack.
Before upstreaming gadgetfs needs to be rewritten to use AIO.  Otherwise low
priority.



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