Il 21/05/2012 14:18, Michael S. Tsirkin ha scritto: >> > Almost all our >> > devices were written without any thought given to ordering, so they >> > basically can and should be considered as all broken. > Problem is, a lot of code is likely broken even after you sprinkle > barriers around. For example qemu might write A then B where guest driver > expects to see B written before A.
This would be a bug in the guest driver, and usually relatively easy to reproduce. The specs (I know of UHCI) should be very precise on this for obvious reasons. Paolo
