From: Michael Kelley <mikelley@xxxxxxxxxxxxx> Sent: Wednesday, September 18, 2019 2:48 PM > > > > Without deferred IO support, hyperv_fb driver informs the host to refresh > > the entire guest frame buffer at fixed rate, e.g. at 20Hz, no matter there > > is screen update or not. This patch supports deferred IO for screens in > > graphics mode and also enables the frame buffer on-demand refresh. The > > highest refresh rate is still set at 20Hz. > > > > Currently Hyper-V only takes a physical address from guest as the starting > > address of frame buffer. This implies the guest must allocate contiguous > > physical memory for frame buffer. In addition, Hyper-V Gen 2 VMs only > > accept address from MMIO region as frame buffer address. Due to these > > limitations on Hyper-V host, we keep a shadow copy of frame buffer > > in the guest. This means one more copy of the dirty rectangle inside > > guest when doing the on-demand refresh. This can be optimized in the > > future with help from host. For now the host performance gain from deferred > > IO outweighs the shadow copy impact in the guest. > > > > Signed-off-by: Wei Hu <weh@xxxxxxxxxxxxx> Sasha -- this patch and one other from Wei Hu for the Hyper-V frame buffer driver should be ready. Both patches affect only the Hyper-V frame buffer driver so can go through the Hyper-V tree. Can you pick these up? Thx. Michael
