On Tue, 9 Apr 2019 at 17:12, kraxel@xxxxxxxxxx <kraxel@xxxxxxxxxx> wrote: > > Hi, > > > If not for TTM, what would be the alternative? One VMA manager per > > memory region per device? > > Depends pretty much on the device. > > The cirrus is a display device with only 4 MB of vram. You can't fit > much in there. A single 1024x768 @ 24bpp framebuffer needs more 50% > of the video memory already. Which is why the cirrus driver (before the > rewrite) had to migrate buffers from/to vram on every page flip[1]. Which > is one[2] of the reasons why cirrus (after rewrite) doesn't ttm-manage the > vram any more. gem objects are managed with the shmem helpers instead > and the active framebuffer is blitted to vram. > > The qemu stdvga (bochs driver) has 16 MB vram by default and can be > configured to have up to 256 MB. Plenty of room even for multiple 4k > framebuffers if needed. So for the bochs driver all the ttm bo > migration logic is not needed, it could just store everything in vram. To clarify I assume you mean it doesn't need the migrate each bo logic, but it still needs the when VRAM fills up migrate stuff logic. Dave. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
