On 19/03/2018 17:53, Konrad Rzeszutek Wilk wrote: >> None specifically, but it is otherwise "normal" behavior of some >> VMs. Apparently it used to be a common method to synchronize writes >> to other I/O ports. In the commit thread for the original commit >> no-one was able to reproduce it. There are no details on what >> processors are impacted or exactly what the "exceptions and >> instability in the host kernel" were. > > <blinks> There are OSes out there that use a "debug" port to > synchronize I/O port access? That seems ill-advised? What are those > OSes? Linux, see arch/x86/kernel/io_delay.c. Paolo
