X / DRM (Direct Rendering Manager) Architectural Overview

2007 © Moriyoshi Koizumi. All Rights Reserved.

MI

OpenGL I/FXlib I/Flibdrm I/F IOCTL / mmap

Mesa

Xclient (w/GL)

DGA

sockets

vidmode

XAA

Xv

sockets

Xlib

X protocol

X Server (device-independent tier)

VideoDriver

IOCTL / mmap

libdrm

libdrmDRI

XFree86 TierDIX I/F

XFree86 Extension I/F

libdrm I/F

Kernel

Xlib I/F DirectRenderingManager

Filesystem Driver I/F

PCI DeviceManager

Filesystem Driver I/F Hard-

ware

AGP GARTManagerMemory

ManagerSubsystem

AGP GARTManagerI/F

IRQAbstraction

IOCTL / mmap

FilesystemAbstraction

MM I/F

IRQM I/F

PCI Driver I/F

X Window / Direct RenderingArchitectural Diagram

PCI Driver I/F


MI

OpenGL I/FXlib I/F

Mesa

Xclient (w/GL)

DGA

sockets

vidmode

XAA

Xv

sockets

Xlib

X protocol

X Server (DIX)

VideoDriver

IOCTL / mmap

libdrmDRI

XFree86 TierDIX I/F

XFree86 Extension I/F

libdrm I/F

Kernel

Xlib I/F DirectRenderingManager

Filesystem Driver I/F

PCI DeviceManager

Filesystem Driver I/F Hard-

ware

AGP GARTManagerMemory

ManagerSubsystem

AGP GARTManagerI/F

IRQAbstraction

IOCTL / mmap

FilesystemAbstraction

MM I/F

IRQM I/F

PCI Driver I/F

X Window / Indirect RenderingArchitectural Diagram

PCI Driver I/F

GLX Mesa


Address Space Layout

GART

ActualRAMSpace

Kernel Space

User SpacePhysical Address Space

MMIOSpace

GraphicsAperture


InstructionBuffer

Direct Memory Access1. Queueing

Kernel Space

FIFO

Graphic Controller

User SpaceIOCTL (BLIT etc.)

DMA Transfer

MarkedConsistent

Some Process


Active Entry

Direct Memory Access 2. Bitmap Block Transfer (Blit)

Kernel Space

FIFO

Graphic Controller

User Space

Blit Engine

Parse & Dispatch

DMA Transfer

MarkedConsistent

SomeProcess

Another Process


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


DRM Authentication

DRI

Mesa libdrm

libdrm

Kernel

1. Retrieve Magic Cookie (drmGetMagic())

X protocol

X Server

XFree86 Tier

Xlib

3. Send Magic (XF86DRIAuthConnection())

DirectRenderingManager

2. Generate Magic Cookie

4. Authenticate Cookie(drmAuthMagic())

Cookie Manager


DRM Authentication(Userland Wrappers)

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;}

libdrm/xf86drm.c:(formally: xc/programs/Xserver/hw/xfree86/os-support/linux/drm/xf86drm.c)


DRM Authentication(Userland Wrappers)

BoolDRIAuthConnection(ScreenPtr pScreen, drm_magic_t magic){ DRIScreenPrivPtr pDRIPriv = DRI_SCREEN_PRIV(pScreen);

if (drmAuthMagic(pDRIPriv->drmFD, magic)) return FALSE; return TRUE;}

xc/programs/Xserver/hw/xfree86/dri/dri.c:

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;

}


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},...


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("no function\n");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);

}


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)

{.../* Find unique magic */if (priv->magic) {

auth.magic = priv->magic;} else {

do {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("%u\n", auth.magic);if (copy_to_user((drm_auth_t __user *) arg, &auth, sizeof(auth)))

return -EFAULT;return 0;

}

typedef unsigned int drm_magic_t;

typedef struct drm_auth {drm_magic_t magic;

} drm_auth_t;


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("%u\n", auth.magic);if ((file = drm_find_file(dev, auth.magic))) {

file->authenticated = 1;drm_remove_magic(dev, auth.magic);return 0;

}return -EINVAL;

}


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;

}


SAREAFrame Buffer

Texture Buffer

GART

Graphic Address Remapping Table(GART)

ActualRAMSpace

VirtualMemorySpace

VirtualMemorySpace

Process #1

Process #2

Phy-Virt Address Translation (by MMU)

Physical Address Space

MMIOSpace

Phy-Phy Address Translation(by AGP controller)

GraphicsAperture


AGPGART IOCTL I/F

● ACQUIRE● SETUP● RESERVE● PROTECT● ALLOCATE / DEALLOCATE● BIND / UNBIND

Technology

X / DRM (Direct Rendering Manager) Architectural Overview