From Spice

Contents 1 DRM 2 Summary 3 Owner 4 Current Status 5 Description 5.1 Steps 5.1.1 DRM driver standalone 5.1.2 dumb ioctl 5.1.3 ioctl design 5.1.4 ioctl implementation 5.1.5 X driver 5.1.6 Some graphics to show I know how to use asciio

DRM

Summary

DRM (Direct Rendering Manager) driver for Linux.

Owner

• Alon Levy

Current Status

• Targeted Release: spice-0.12
• 50% complete
• git://anongit.freedesktop.org/~alon/linux qxl
• Fedora feature page: https://fedoraproject.org/wiki/Features/QXLKMSSupport

Description

DRM driver for linux. Provides kernel mode setting (KMS), switch to qxl native mode from loading (instead of at X), follow up with rewriting of X driver to use it to allocate memory. Deallocation will still happen in the Kernel driver.

Steps

DRM driver standalone

• fb operations: single allocator carving up space for command+palette+image+chunk. optimize later
• single bo for ioctl allocated memory. use radeon scheme? 16 buffers corresponding to drawing buffers which are pixmaps.
• allocator: ttm
• fb mode image cache
  • currently don't cache anything.
  • can take the cache implementation from xf86-video-qxl (it's actually already there, just disabled).
• applications that have to work before next stage - anything using fb:
  • regular console:
  • plymouth
  • X with modesetting driver
  • X with qxl driver

dumb ioctl

• work with xf86-video-modesetting
  • http://cgit.freedesktop.org/xorg/driver/xf86-video-modesetting
• by implementing the three dumb callbacks:
  • .dumb_create = radeon_mode_dumb_create,
    • DRM_IOCTL_MODE_CREATE_DUMB
  • .dumb_map_offset = radeon_mode_dumb_mmap,
    • drm_mode_mmap_dumb_ioctl / DRM_IOCTL_MODE_MAP_DUMB
  • .dumb_destroy = radeon_mode_dumb_destroy,
    • DRM_IOCTL_MODE_DESTROY_DUMB

ioctl design

ioctl implementation

X driver

Some graphics to show I know how to use asciio

C - changed N - new

         .------------------.
         |       App        |
         |                  |
         |   .--------.     |
         |   | libX11 |     |
         |   '--------'     |
         '--------|---------'
                  v
     .-------------------------.
     |          Xorg           |
     |                         |
     | .CCCCCCCCCCCCCCCCCCCCC. |
     | |     qxl_drv.so      | |
     | | changes: use libdrm | |
     | '---------------------' |
     |                         |
     |    .NNNNNNNNNNNNNNN.    |
     |    |  libdrm_qxl   |    |
     |    '---------------'    |
     '------------|------------'
                  |
                  v
    .---------------------------.
    |          kernel           |
    |                           |
    |    .NNNNNNNNNNNNNNN.      |
    |    |    qxl.ko     |      |
    |    '---------------'      |
    '------------|--------------'
                 |
                 v
     .-----------------------.
     |         qemu          |
     |                       |
     |  .------------------. |
     |  .       qxl        . |
     |  '------------------' |
     |            |          |
     '------------|----------'
                  |
                  v
       .---------------------.
       |       server        |
       |                     |
       '---------------------'