> From: Dexuan Cui <decui@xxxxxxxxxxxxx> > Sent: Wednesday, May 4, 2022 10:05 AM > To: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>; Wei Liu <wei.liu@xxxxxxxxxx>; > > ... > > When I initially implemented this driver 10 years ago, I believe there > > was smaller limit for the fb... But I think this patch is good for the > > newer MMIO alloc scheme. I hope to see reviews also from > > @Dexuan Cui @Michael Kelley (LINUX) who are more familiar with > > the PCI/BAR/MMIO area. > > > > Thanks, > > - Haiyang > > The patch looks good to me but I suggest we check with the Hyper-V > team to figure out how a Gen1 Windows VM supports a higher > resolution that needs a VRAM size of more than 64MB. Just in case we > miss something.. > > Thanks, > -- Dexuan Reviewed-by: Dexuan Cui <decui@xxxxxxxxxxxxx> Saurabh checked this with Hyper-V team, who said there is no Generation 1-specific block for larger VRAM sizes in Windows VM. When the driver was originally developed, we didn't have the API vmbus_allocate_mmio(), and I guess we just used the PCI device's BAR address for simplicity, and didn't realize the restriction with very high resolutions that require >64 MB VRAM. It looks like the synthetic VMBus framebuffer device doesn't have to use the same MMIO range used by the Hyper-V legacy PCI framebuffer device, so the patch looks good to me. BTW, please check the hyperv-drm driver as well: drivers/gpu/drm/hyperv/hyperv_drm_drv.c I think we should make the same change there to support 7680x4320 for Gen1 VMs. Thanks, Dexuan
