1. X Window / Direct Rendering
Architectural Diagram
Xclient (w/GL)
OpenGL I/F
Xlib I/F Filesystem
libdrm I/F IOCTL / mmap
Driver I/F
Mesa libdrm
PCI
Direct
Xlib Xlib I/F
Driver
Rendering
I/F
Manager
Filesystem
sockets Abstraction
AGP GART
Manager
X protocol Filesystem I/F
Driver I/F Hard-
Kernel
sockets
X Server (device-independent tier) ware
AGP GART
libdrm I/F
XFree86 Tier
Manager
DIX IOCTL / Memory
libdrm
I/F DGA DRI mmap Manager MM
PCI
Subsystem I/F
Driver
vidmode
I/F
Video
XFree86 IOCTL /
IRQ
XAA
PCI Device
Extension mmap
Driver Abstraction IRQM
MI I/F
Manager
I/F
Xv
2007 © Moriyoshi Koizumi. All Rights Reserved.

2. X Window / Indirect Rendering
Architectural Diagram
Xclient (w/GL)
OpenGL I/F
Xlib I/F Filesystem
Driver I/F
Mesa
PCI
Direct
Xlib Xlib I/F
Driver
Rendering
I/F
Manager
Filesystem
sockets Abstraction
AGP GART
Manager
X protocol Filesystem I/F
Driver I/F Hard-
Kernel
sockets
X Server (DIX) ware
GLX Mesa
AGP GART
XFree86 Tier libdrm I/F
Manager
DIX IOCTL / Memory
libdrm
I/F DGA DRI mmap Manager MM
PCI
Subsystem I/F
Driver
vidmode
I/F
Video
XFree86 IOCTL /
IRQ
XAA
PCI Device
Extension mmap
Driver Abstraction IRQM
MI I/F
Manager
I/F
Xv
2007 © Moriyoshi Koizumi. All Rights Reserved.

3. Address Space Layout
Kernel Space
Graphics
MMIO Aperture
Space
Physical
User Space
Address
Space
Actual
RAM
Space
GART
2007 © Moriyoshi Koizumi. All Rights Reserved.

4. Direct Memory Access
1. Queueing
Kernel Space Graphic Controller
Instruction
Buffer DMA FIFO
Transfer
Marked
Consistent IOCTL (BLIT etc.)
User Space
Some
Process
2007 © Moriyoshi Koizumi. All Rights Reserved.

5. Direct Memory Access
2. Bitmap Block Transfer (Blit)
Kernel Space Graphic Controller
Active Entry
FIFO
Parse &
User Space Dispatch
Some
Marked
Process Blit Engine
Consistent
DMA Transfer
Another
Process
2007 © Moriyoshi Koizumi. All Rights Reserved.

6. DRM IOCTL I/F
AUTH (GET_MAGIC / AUTH_MAGIC)
●
VERSION (GET / SET)
●
BUSID (GET / SET)
●
MAP (ADD / RM)
●
CTX (ADD / RM / GET / SWITCH / NEW /
●
RESERVE)
LOCK (LOCK / UNLOCK)
●
AGP operations
●
Device-specific operations
●
2007 © Moriyoshi Koizumi. All Rights Reserved.

7. DRM Authentication
1. Retrieve Magic Cookie (drmGetMagic())
Cookie Manager
Mesa libdrm
2. Generate
Direct
Xlib
Magic
Rendering
Manager Cookie
3. Send Magic
X protocol (XF86DRIAuthConnection()) 4. Authenticate Cookie
(drmAuthMagic())
Kernel
X Server
XFree86 Tier
libdrm
DRI
2007 © Moriyoshi Koizumi. All Rights Reserved.

8. DRM Authentication
(Userland Wrappers)
libdrm/xf86drm.c:
(formally: xc/programs/Xserver/hw/xfree86/os-support/linux/drm/xf86drm.c)
int drmGetMagic(int fd, drm_magic_t * magic)
{
drm_auth_t auth;
*magic = 0;
if (ioctl(fd, DRM_IOCTL_GET_MAGIC, &auth)) return -errno;
*magic = auth.magic;
return 0;
}
2007 © Moriyoshi Koizumi. All Rights Reserved.

9. DRM Authentication
(Userland Wrappers)
xc/programs/Xserver/hw/xfree86/dri/dri.c:
Bool
DRIAuthConnection(ScreenPtr pScreen, drm_magic_t magic)
{
DRIScreenPrivPtr pDRIPriv = DRI_SCREEN_PRIV(pScreen);
if (drmAuthMagic(pDRIPriv->drmFD, magic)) return FALSE;
return TRUE;
}
libdrm/xf86drm.c:
(formally: xc/programs/Xserver/hw/xfree86/os-support/linux/drm/xf86drm.c)
int drmAuthMagic(int fd, drm_magic_t magic)
{
drm_auth_t auth;
auth.magic = magic;
if (ioctl(fd, DRM_IOCTL_AUTH_MAGIC, &auth)) return -errno;
return 0;
}
2007 © Moriyoshi Koizumi. All Rights Reserved.

10. DRM Authentication
(linux/drivers/char/drm/drm_drv.c: IOCTL Dispatch Table)
static drm_ioctl_desc_t drm_ioctls[] = {
[DRM_IOCTL_NR(DRM_IOCTL_VERSION)] = {drm_version, 0},
[DRM_IOCTL_NR(DRM_IOCTL_GET_UNIQUE)] = {drm_getunique,
0},
[DRM_IOCTL_NR(DRM_IOCTL_GET_MAGIC)] = {drm_getmagic, 0},
[DRM_IOCTL_NR(DRM_IOCTL_IRQ_BUSID)] = {drm_irq_by_busid,
DRM_MASTER|DRM_ROOT_ONLY},
[DRM_IOCTL_NR(DRM_IOCTL_GET_MAP)] = {drm_getmap, 0},
[DRM_IOCTL_NR(DRM_IOCTL_GET_CLIENT)] = {drm_getclient,
0},
[DRM_IOCTL_NR(DRM_IOCTL_SET_VERSION)] = {drm_setversion,
DRM_MASTER|DRM_ROOT_ONLY},
[DRM_IOCTL_NR(DRM_IOCTL_AUTH_MAGIC)] = {drm_authmagic,
DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY},
[DRM_IOCTL_NR(DRM_IOCTL_ADD_CTX)] = {drm_addctx,
DRM_AUTH|DRM_ROOT_ONLY},
[DRM_IOCTL_NR(DRM_IOCTL_GET_CTX)] = {drm_getctx,
DRM_AUTH},
...
2007 © Moriyoshi Koizumi. All Rights Reserved.

11. DRM Authentication
(linux/drivers/char/drm/drm_drv.c: IOCTL Dispatcher)
if (nr < DRIVER_IOCTL_COUNT)
ioctl = &drm_ioctls[nr];
else if ((nr >= DRM_COMMAND_BASE)
&& (nr < DRM_COMMAND_BASE + dev->driver->num_ioctls))
ioctl = &dev->driver->ioctls[nr - DRM_COMMAND_BASE];
else
goto err_i1;
func = ioctl->func;
/* is there a local override? */
if ((nr == DRM_IOCTL_NR(DRM_IOCTL_DMA)) && dev->driver->dma_ioctl)
func = dev->driver->dma_ioctl;
if (!func) {
DRM_DEBUG(quot;no functionnquot;);
retcode = -EINVAL;
} else if (((ioctl->flags & DRM_ROOT_ONLY) && !capable(CAP_SYS_ADMIN)) ||
((ioctl->flags & DRM_AUTH) && !priv->authenticated) ||
((ioctl->flags & DRM_MASTER) && !priv->master)) {
retcode = -EACCES;
} else {
retcode = func(inode, filp, cmd, arg);
}
2007 © Moriyoshi Koizumi. All Rights Reserved.

12. DRM Authentication
(linux/drivers/char/drm/drm_auth.c: Cookie Issuer)
int drm_getmagic(struct inode *inode, struct file *filp,
unsigned int cmd, unsigned long arg)
{
...
typedef unsigned int drm_magic_t;
/* Find unique magic */
if (priv->magic) {
typedef struct drm_auth {
auth.magic = priv->magic;
drm_magic_t magic;
} else {
do { } drm_auth_t;
spin_lock(&lock);
if (!sequence)
++sequence;/* reserve 0 */
auth.magic = sequence++;
spin_unlock(&lock);
} while (drm_find_file(dev, auth.magic));
priv->magic = auth.magic;
drm_add_magic(dev, priv, auth.magic);
}
DRM_DEBUG(quot;%unquot;, auth.magic);
if (copy_to_user((drm_auth_t __user *) arg, &auth, sizeof(auth)))
return -EFAULT;
return 0;
}
2007 © Moriyoshi Koizumi. All Rights Reserved.

13. DRM Authentication
(linux/drivers/char/drm/drm_auth.c: Cookie Verifier)
int drm_authmagic(struct inode *inode, struct file *filp,
unsigned int cmd, unsigned long arg)
{
drm_file_t *priv = filp->private_data;
drm_device_t *dev = priv->head->dev;
drm_auth_t auth;
drm_file_t *file;
if (copy_from_user(&auth, (drm_auth_t __user *) arg, sizeof(auth)))
return -EFAULT;
DRM_DEBUG(quot;%unquot;, auth.magic);
if ((file = drm_find_file(dev, auth.magic))) {
file->authenticated = 1;
drm_remove_magic(dev, auth.magic);
return 0;
}
return -EINVAL;
}
2007 © Moriyoshi Koizumi. All Rights Reserved.

14. DRM Authentication
(linux/drivers/char/drm/drm_auth.c: Cookie Keeper)
static drm_file_t *drm_find_file(drm_device_t * dev, drm_magic_t magic)
{
drm_file_t *retval = NULL;
drm_magic_entry_t *pt;
int hash = drm_hash_magic(magic);
mutex_lock(&dev->struct_mutex);
for (pt = dev->magiclist[hash].head; pt; pt = pt->next) {
if (pt->magic == magic) {
retval = pt->priv;
break;
}
}
mutex_unlock(&dev->struct_mutex);
return retval;
}
2007 © Moriyoshi Koizumi. All Rights Reserved.

15. Graphic Address Remapping Table
(GART)
SAREA
Frame Buffer Phy-Phy Address Translation
Texture Buffer Process #1
(by AGP controller)
Graphics
MMIO Aperture Virtual
Space Memory
Space
Physical
Process #2
Address
Space
Actual Virtual
RAM Memory
Space Space
GART
Phy-Virt Address
Translation (by MMU)
2007 © Moriyoshi Koizumi. All Rights Reserved.

16. AGPGART IOCTL I/F
ACQUIRE
●
SETUP
●
RESERVE
●
PROTECT
●
ALLOCATE / DEALLOCATE
●
BIND / UNBIND
●
2007 © Moriyoshi Koizumi. All Rights Reserved.