On Thu, 17 Oct 2019 at 14:21, Peter Maydell <peter.mayd...@linaro.org> wrote: > > This patchset converts the devices used by ppc and microblaze > machines to the new ptimer API. (xilinx_timer is used by both, > hence putting both archs in the same patchset). > > Currently the ptimer design uses a QEMU bottom-half as its mechanism > for calling back into the device model using the ptimer when the > timer has expired. Unfortunately this design is fatally flawed, > because it means that there is a lag between the ptimer updating its > own state and the device callback function updating device state, and > guest accesses to device registers between the two can return > inconsistent device state. This was reported as a bug in a specific > timer device but it's a problem with the generic ptimer code: > https://bugs.launchpad.net/qemu/+bug/1777777 > > The updates to the individual ptimer devices are straightforward: > we need to add begin/commit calls around the various places that > modify the ptimer state, and use the new ptimer_init() function > to create the timer. > > Testing has been 'make check' only, which obviously doesn't > exercise the devices very much, so more specific testing would > be appreciated. I'm happy for these patches to go in via the > ppc tree if you want, or I can collect them up with the other > ptimer-related changes I'm sending for other archs.
I'll put these in via target-arm.next, since they've all been reviewed now and nobody's suggested a preference for some other route. thanks -- PMM
