On 2011-02-07 17:23, Paolo Bonzini wrote: > On 02/07/2011 05:03 PM, Marcelo Tosatti wrote: >> Is there any other issue that prevents turning CONFIG_IOTHREAD on by >> default? > > I think Windows support. > > Signal support is actually easy because we can "hack" the IPI as > "suspend the VCPU thread+do work in the iothread context+resume the VCPU > thread" (the IPI handler doesn't longjmp). > > Threading primitives support is tricky but not hard (there is lots of > code around, especially if you can make assumptions such as "always hold > the mutex while signaling a cond. variable").
!CONFIG_IOTHREAD code is doomed to bitrot once we switch to default iothread mode. So if Windows support is not converted to a threading model with moderate differences to POSIX, it will likely bitrot a well. Therefore, conversion should be started rather sooner than later (by someone interested in that platform). Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux
