src/mesa/drivers/dri/i830/i830_context.c

   1 /**************************************************************************
   2  *
   3  * Copyright 1998-1999 Precision Insight, Inc., Cedar Park, Texas.
   4  * All Rights Reserved.
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a
   7  * copy of this software and associated documentation files (the
   8  * "Software"), to deal in the Software without restriction, including
   9  * without limitation the rights to use, copy, modify, merge, publish,
  10  * distribute, sub license, and/or sell copies of the Software, and to
  11  * permit persons to whom the Software is furnished to do so, subject to
  12  * the following conditions:
  13  *
  14  * The above copyright notice and this permission notice (including the
  15  * next paragraph) shall be included in all copies or substantial portions
  16  * of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  20  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
  21  * IN NO EVENT SHALL PRECISION INSIGHT AND/OR ITS SUPPLIERS BE LIABLE FOR
  22  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  23  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  24  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  * **************************************************************************/
  27 /* $XFree86: xc/lib/GL/mesa/src/drv/i830/i830_context.c,v 1.9 2003/02/06 04:18:00 dawes Exp $ */
  28
  29 /*
  30  * Authors:
  31  *   Jeff Hartmann <jhartmann@2d3d.com>
  32  *   Graeme Fisher <graeme@2d3d.co.za>
  33  *   Abraham vd Merwe <abraham@2d3d.co.za>
  34  *
  35  * Heavily Based on I810 driver written by:
  36  *   Keith Whitwell <keith@tungstengraphics.com>
  37  */
  38
  39 #include "glheader.h"
  40 #include "context.h"
  41 #include "matrix.h"
  42 #include "simple_list.h"
  43 #include "extensions.h"
  44 #include "imports.h"
  45
  46 #include "swrast/swrast.h"
  47 #include "swrast_setup/swrast_setup.h"
  48 #include "tnl/tnl.h"
  49 #include "array_cache/acache.h"
  50
  51 #include "tnl/t_pipeline.h"
  52
  53 #include "drivers/common/driverfuncs.h"
  54
  55 #include "i830_screen.h"
  56 #include "i830_dri.h"
  57
  58 #include "i830_state.h"
  59 #include "i830_tex.h"
  60 #include "i830_span.h"
  61 #include "i830_tris.h"
  62 #include "i830_ioctl.h"
  63
  64
  65 #include "utils.h"
  66 #ifndef I830_DEBUG
  67 int I830_DEBUG = (0);
  68 #endif
  69
  70 /***************************************
  71  * Mesa's Driver Functions
  72  ***************************************/
  73
  74 #define DRIVER_DATE                     "20021115"
  75
  76
  77 const char __driConfigOptions[] = { 0 };
  78 const GLuint __driNConfigOptions = 0;
  79
  80 static const GLubyte *i830DDGetString( GLcontext *ctx, GLenum name )
  81 {
  82    const char * chipset;
  83    static char buffer[128];
  84
  85    switch (name) {
  86    case GL_VENDOR:
  87       switch (I830_CONTEXT(ctx)->i830Screen->deviceID) {
  88       case PCI_CHIP_845_G:
  89          return (GLubyte *)"2d3D, Inc";
  90
  91       case PCI_CHIP_I830_M:
  92          return (GLubyte *)"VA Linux, Inc";
  93
  94       case PCI_CHIP_I855_GM:
  95       case PCI_CHIP_I865_G:
  96       default:
  97          return (GLubyte *)"Tungsten Graphics, Inc";
  98       }
  99       break;
 100
 101    case GL_RENDERER:
 102       switch (I830_CONTEXT(ctx)->i830Screen->deviceID) {
 103       case PCI_CHIP_845_G:
 104          chipset = "Intel(R) 845G"; break;
 105       case PCI_CHIP_I830_M:
 106          chipset = "Intel(R) 830M"; break;
 107       case PCI_CHIP_I855_GM:
 108          chipset = "Intel(R) 852GM/855GM"; break;
 109       case PCI_CHIP_I865_G:
 110          chipset = "Intel(R) 865G"; break;
 111       default:
 112          chipset = "Unknown Intel Chipset"; break;
 113       }
 114
 115       (void) driGetRendererString( buffer, chipset, DRIVER_DATE, 0 );
 116       return (GLubyte *) buffer;
 117
 118    default:
 119       return NULL;
 120    }
 121 }
 122
 123 static void i830BufferSize(GLframebuffer *buffer,
 124                            GLuint *width, GLuint *height)
 125 {
 126    GET_CURRENT_CONTEXT(ctx);
 127    i830ContextPtr imesa = I830_CONTEXT(ctx);
 128    /* Need to lock to make sure the driDrawable is uptodate.  This
 129     * information is used to resize Mesa's software buffers, so it has
 130     * to be correct.
 131     */
 132    LOCK_HARDWARE(imesa);
 133    *width = imesa->driDrawable->w;
 134    *height = imesa->driDrawable->h;
 135    UNLOCK_HARDWARE(imesa);
 136 }
 137
 138
 139 /* Extension strings exported by the i830 driver.
 140  */
 141 static const char * const card_extensions[] =
 142 {
 143    "GL_ARB_multisample",
 144    "GL_ARB_multitexture",
 145    "GL_ARB_texture_border_clamp",
 146    "GL_ARB_texture_compression",
 147    "GL_ARB_texture_env_add",
 148    "GL_ARB_texture_env_combine",
 149    "GL_ARB_texture_env_dot3",
 150    "GL_ARB_texture_mirrored_repeat",
 151    "GL_EXT_blend_color",
 152    "GL_EXT_blend_func_separate",
 153    "GL_EXT_blend_minmax",
 154    "GL_EXT_blend_subtract",
 155    "GL_EXT_fog_coord",
 156    "GL_EXT_secondary_color",
 157    "GL_EXT_stencil_wrap",
 158    "GL_EXT_texture_edge_clamp",
 159    "GL_EXT_texture_env_combine",
 160    "GL_EXT_texture_env_dot3",
 161    "GL_EXT_texture_filter_anisotropic",
 162    "GL_EXT_texture_lod_bias",
 163    "GL_EXT_texture_rectangle",
 164    "GL_MESA_ycbcr_texture",
 165    "GL_SGIS_generate_mipmap",
 166    NULL
 167 };
 168
 169
 170 extern const struct tnl_pipeline_stage _i830_render_stage;
 171
 172 static const struct tnl_pipeline_stage *i830_pipeline[] = {
 173    &_tnl_vertex_transform_stage,
 174    &_tnl_normal_transform_stage,
 175    &_tnl_lighting_stage,
 176    &_tnl_fog_coordinate_stage,
 177    &_tnl_texgen_stage,
 178    &_tnl_texture_transform_stage,
 179                                 /* REMOVE: point attenuation stage */
 180 #if 1
 181    &_i830_render_stage,     /* ADD: unclipped rastersetup-to-dma */
 182 #endif
 183    &_tnl_render_stage,
 184    0,
 185 };
 186
 187
 188 static const struct dri_debug_control debug_control[] =
 189 {
 190     { "fall",  DEBUG_FALLBACKS },
 191     { "tex",   DEBUG_TEXTURE },
 192     { "ioctl", DEBUG_IOCTL },
 193     { "prim",  DEBUG_PRIMS },
 194     { "vert",  DEBUG_VERTS },
 195     { "state", DEBUG_STATE },
 196     { "verb",  DEBUG_VERBOSE },
 197     { "dri",   DEBUG_DRI },
 198     { "dma",   DEBUG_DMA },
 199     { "san",   DEBUG_SANITY },
 200     { "sync",  DEBUG_SYNC },
 201     { "sleep", DEBUG_SLEEP },
 202     { NULL,    0 }
 203 };
 204
 205
 206 GLboolean i830CreateContext( const __GLcontextModes *mesaVis,
 207                              __DRIcontextPrivate *driContextPriv,
 208                              void *sharedContextPrivate)
 209 {
 210    GLcontext *ctx , *shareCtx;
 211    i830ContextPtr imesa;
 212    __DRIscreenPrivate *sPriv = driContextPriv->driScreenPriv;
 213    i830ScreenPrivate *screen = (i830ScreenPrivate *)sPriv->private;
 214    I830SAREAPtr saPriv=(I830SAREAPtr)
 215        (((GLubyte *)sPriv->pSAREA)+screen->sarea_priv_offset);
 216    struct dd_function_table functions;
 217
 218    /* Allocate i830 context */
 219    imesa = (i830ContextPtr) CALLOC_STRUCT(i830_context_t);
 220    if (!imesa)
 221       return GL_FALSE;
 222
 223    /* Init default driver functions then plug in our I830-specific functions
 224     * (the texture functions are especially important)
 225     */
 226    _mesa_init_driver_functions(&functions);
 227    i830InitIoctlFuncs(&functions);
 228    i830InitTextureFuncs(&functions);
 229
 230    /* Allocate the Mesa context */
 231    if (sharedContextPrivate)
 232      shareCtx = ((i830ContextPtr) sharedContextPrivate)->glCtx;
 233    else
 234      shareCtx = NULL;
 235    imesa->glCtx = _mesa_create_context(mesaVis, shareCtx,
 236                                        &functions, (void*) imesa);
 237    if (!imesa->glCtx) {
 238       FREE(imesa);
 239       return GL_FALSE;
 240    }
 241    driContextPriv->driverPrivate = imesa;
 242
 243
 244    imesa->i830Screen = screen;
 245    imesa->driScreen = sPriv;
 246    imesa->sarea = saPriv;
 247    imesa->glBuffer = NULL;
 248
 249
 250    (void) memset( imesa->texture_heaps, 0, sizeof( imesa->texture_heaps ) );
 251    make_empty_list( & imesa->swapped );
 252
 253    imesa->nr_heaps = 1;
 254    imesa->texture_heaps[0] = driCreateTextureHeap( 0, imesa,
 255             screen->textureSize,
 256             12,
 257             I830_NR_TEX_REGIONS,
 258             imesa->sarea->texList,
 259             (unsigned *) & imesa->sarea->texAge, /* XXX shouldn't need cast! */
 260             & imesa->swapped,
 261             sizeof( struct i830_texture_object_t ),
 262             (destroy_texture_object_t *) i830DestroyTexObj );
 263
 264
 265    /* Set the maximum texture size small enough that we can guarantee
 266     * that both texture units can bind a maximal texture and have them
 267     * in memory at once.
 268     */
 269
 270    ctx = imesa->glCtx;
 271    ctx->Const.MaxTextureUnits = 2;
 272    ctx->Const.MaxTextureImageUnits = 2;
 273    ctx->Const.MaxTextureCoordUnits = 2;
 274
 275    /* FIXME: driCalculateMaxTextureLevels assumes that mipmaps are tightly
 276     * FIXME: packed, but they're not in Intel graphics hardware.
 277     */
 278    driCalculateMaxTextureLevels( imesa->texture_heaps,
 279                                  imesa->nr_heaps,
 280                                  & ctx->Const,
 281                                  4,
 282                                  11, /* max 2D texture size is 2048x2048 */
 283                                  0,  /* 3D textures unsupported */
 284                                  0,  /* cube textures unsupported. */
 285                                  0,  /* texture rectangles unsupported. */
 286                                  12,
 287                                  GL_FALSE );
 288
 289    ctx->Const.MaxTextureMaxAnisotropy = 2.0;
 290
 291    ctx->Const.MinLineWidth = 1.0;
 292    ctx->Const.MinLineWidthAA = 1.0;
 293    ctx->Const.MaxLineWidth = 3.0;
 294    ctx->Const.MaxLineWidthAA = 3.0;
 295    ctx->Const.LineWidthGranularity = 1.0;
 296
 297    ctx->Const.MinPointSize = 1.0;
 298    ctx->Const.MinPointSizeAA = 1.0;
 299    ctx->Const.MaxPointSize = 255.0;
 300    ctx->Const.MaxPointSizeAA = 3.0;
 301    ctx->Const.PointSizeGranularity = 1.0;
 302
 303    ctx->Driver.GetBufferSize = i830BufferSize;
 304    ctx->Driver.ResizeBuffers = _swrast_alloc_buffers;
 305    ctx->Driver.GetString = i830DDGetString;
 306
 307    /* Who owns who? */
 308    ctx->DriverCtx = (void *) imesa;
 309    imesa->glCtx = ctx;
 310
 311    /* Initialize the software rasterizer and helper modules. */
 312    _swrast_CreateContext( ctx );
 313    _ac_CreateContext( ctx );
 314    _tnl_CreateContext( ctx );
 315    _swsetup_CreateContext( ctx );
 316
 317    /* Install the customized pipeline: */
 318    _tnl_destroy_pipeline( ctx );
 319    _tnl_install_pipeline( ctx, i830_pipeline );
 320
 321    /* Configure swrast to match hardware characteristics: */
 322    _swrast_allow_pixel_fog( ctx, GL_FALSE );
 323    _swrast_allow_vertex_fog( ctx, GL_TRUE );
 324
 325    /* Dri stuff */
 326    imesa->hHWContext = driContextPriv->hHWContext;
 327    imesa->driFd = sPriv->fd;
 328    imesa->driHwLock = &sPriv->pSAREA->lock;
 329    imesa->hw_stencil = mesaVis->stencilBits && mesaVis->depthBits == 24;
 330
 331    switch(mesaVis->depthBits) {
 332    case 16:
 333       imesa->depth_scale = 1.0/0xffff;
 334       imesa->depth_clear_mask = ~0;
 335       imesa->ClearDepth = 0xffff;
 336       break;
 337    case 24:
 338       imesa->depth_scale = 1.0/0xffffff;
 339       imesa->depth_clear_mask = 0x00ffffff;
 340       imesa->stencil_clear_mask = 0xff000000;
 341       imesa->ClearDepth = 0x00ffffff;
 342       break;
 343    case 32: /* Not supported */
 344    default:
 345       break;
 346    }
 347    /* Completely disable stenciling for now, there are some serious issues
 348     * with stencil.
 349     */
 350 #if 0
 351    imesa->hw_stencil = 0;
 352 #endif
 353
 354    imesa->RenderIndex = ~0;
 355    imesa->dirty = ~0;
 356    imesa->upload_cliprects = GL_TRUE;
 357
 358    imesa->CurrentTexObj[0] = 0;
 359    imesa->CurrentTexObj[1] = 0;
 360
 361    imesa->do_irqs = (imesa->i830Screen->irq_active &&
 362                      !getenv("I830_NO_IRQS"));
 363
 364    _math_matrix_ctr (&imesa->ViewportMatrix);
 365
 366    driInitExtensions( ctx, card_extensions, GL_TRUE );
 367    /* XXX these should really go right after _mesa_init_driver_functions() */
 368    i830DDInitStateFuncs( ctx );
 369    i830InitTriFuncs (ctx);
 370    i830DDInitSpanFuncs( ctx );
 371    i830DDInitState (ctx);
 372
 373    driInitTextureObjects( ctx, & imesa->swapped,
 374                           DRI_TEXMGR_DO_TEXTURE_2D
 375                           | DRI_TEXMGR_DO_TEXTURE_RECT );
 376
 377 #if DO_DEBUG
 378    I830_DEBUG  = driParseDebugString( getenv( "I830_DEBUG" ),
 379                                       debug_control );
 380    I830_DEBUG |= driParseDebugString( getenv( "INTEL_DEBUG" ),
 381                                       debug_control );
 382 #endif
 383
 384    if (getenv("I830_NO_RAST") ||
 385        getenv("INTEL_NO_RAST")) {
 386       fprintf(stderr, "disabling 3D rasterization\n");
 387       FALLBACK(imesa, I830_FALLBACK_USER, 1);
 388    }
 389
 390    return GL_TRUE;
 391 }
 392
 393 void i830DestroyContext(__DRIcontextPrivate *driContextPriv)
 394 {
 395    i830ContextPtr imesa = (i830ContextPtr) driContextPriv->driverPrivate;
 396
 397    assert(imesa); /* should never be null */
 398    if (imesa) {
 399       GLboolean   release_texture_heaps;
 400
 401
 402       release_texture_heaps = (imesa->glCtx->Shared->RefCount == 1);
 403       _swsetup_DestroyContext (imesa->glCtx);
 404       _tnl_DestroyContext (imesa->glCtx);
 405       _ac_DestroyContext (imesa->glCtx);
 406       _swrast_DestroyContext (imesa->glCtx);
 407
 408       /* free the Mesa context */
 409       imesa->glCtx->DriverCtx = NULL;
 410       _mesa_destroy_context(imesa->glCtx);
 411
 412       if ( release_texture_heaps ) {
 413          /* This share group is about to go away, free our private
 414           * texture object data.
 415           */
 416          int i;
 417
 418          for ( i = 0 ; i < imesa->nr_heaps ; i++ ) {
 419             driDestroyTextureHeap( imesa->texture_heaps[ i ] );
 420             imesa->texture_heaps[ i ] = NULL;
 421          }
 422
 423          assert( is_empty_list( & imesa->swapped ) );
 424       }
 425
 426       FREE(imesa);
 427    }
 428 }
 429
 430 void i830XMesaSetFrontClipRects( i830ContextPtr imesa )
 431 {
 432    __DRIdrawablePrivate *dPriv = imesa->driDrawable;
 433
 434    imesa->numClipRects = dPriv->numClipRects;
 435    imesa->pClipRects = dPriv->pClipRects;
 436    imesa->drawX = dPriv->x;
 437    imesa->drawY = dPriv->y;
 438
 439    i830EmitDrawingRectangle( imesa );
 440    imesa->upload_cliprects = GL_TRUE;
 441 }
 442
 443 void i830XMesaSetBackClipRects( i830ContextPtr imesa )
 444 {
 445    __DRIdrawablePrivate *dPriv = imesa->driDrawable;
 446
 447    if (imesa->sarea->pf_enabled == 0 && dPriv->numBackClipRects == 0) {
 448       imesa->numClipRects = dPriv->numClipRects;
 449       imesa->pClipRects = dPriv->pClipRects;
 450       imesa->drawX = dPriv->x;
 451       imesa->drawY = dPriv->y;
 452    } else {
 453       imesa->numClipRects = dPriv->numBackClipRects;
 454       imesa->pClipRects = dPriv->pBackClipRects;
 455       imesa->drawX = dPriv->backX;
 456       imesa->drawY = dPriv->backY;
 457    }
 458
 459    i830EmitDrawingRectangle( imesa );
 460    imesa->upload_cliprects = GL_TRUE;
 461 }
 462
 463 static void i830XMesaWindowMoved( i830ContextPtr imesa )
 464 {
 465    switch (imesa->glCtx->Color._DrawDestMask) {
 466    case FRONT_LEFT_BIT:
 467       i830XMesaSetFrontClipRects( imesa );
 468       break;
 469    case BACK_LEFT_BIT:
 470       i830XMesaSetBackClipRects( imesa );
 471       break;
 472    default:
 473       /* glDrawBuffer(GL_NONE or GL_FRONT_AND_BACK): software fallback */
 474       i830XMesaSetFrontClipRects( imesa );
 475    }
 476 }
 477
 478 GLboolean i830UnbindContext(__DRIcontextPrivate *driContextPriv)
 479 {
 480    i830ContextPtr imesa = (i830ContextPtr) driContextPriv->driverPrivate;
 481    if (imesa) {
 482       /* Might want to change this so texblend isn't always updated */
 483       imesa->dirty |= (I830_UPLOAD_CTX |
 484                        I830_UPLOAD_BUFFERS |
 485                        I830_UPLOAD_STIPPLE |
 486                        I830_UPLOAD_TEXBLEND0 |
 487                        I830_UPLOAD_TEXBLEND1);
 488
 489       if (imesa->CurrentTexObj[0]) imesa->dirty |= I830_UPLOAD_TEX0;
 490       if (imesa->CurrentTexObj[1]) imesa->dirty |= I830_UPLOAD_TEX1;
 491    }
 492    return GL_TRUE;
 493 }
 494
 495 GLboolean i830MakeCurrent(__DRIcontextPrivate *driContextPriv,
 496                           __DRIdrawablePrivate *driDrawPriv,
 497                           __DRIdrawablePrivate *driReadPriv)
 498 {
 499
 500    if (driContextPriv) {
 501       i830ContextPtr imesa = (i830ContextPtr) driContextPriv->driverPrivate;
 502
 503       if ( imesa->driDrawable != driDrawPriv ) {
 504          /* Shouldn't the readbuffer be stored also? */
 505          imesa->driDrawable = driDrawPriv;
 506          i830XMesaWindowMoved( imesa );
 507       }
 508
 509       _mesa_make_current2(imesa->glCtx,
 510                           (GLframebuffer *) driDrawPriv->driverPrivate,
 511                           (GLframebuffer *) driReadPriv->driverPrivate);
 512
 513       if (!imesa->glCtx->Viewport.Width)
 514          _mesa_set_viewport(imesa->glCtx, 0, 0,
 515                             driDrawPriv->w, driDrawPriv->h);
 516    } else {
 517       _mesa_make_current(0,0);
 518    }
 519
 520    return GL_TRUE;
 521 }
 522
 523 void i830GetLock( i830ContextPtr imesa, GLuint flags )
 524 {
 525    __DRIdrawablePrivate *dPriv = imesa->driDrawable;
 526    __DRIscreenPrivate *sPriv = imesa->driScreen;
 527    I830SAREAPtr sarea = imesa->sarea;
 528    int me = imesa->hHWContext;
 529    unsigned   i;
 530
 531    drmGetLock(imesa->driFd, imesa->hHWContext, flags);
 532
 533    /* If the window moved, may need to set a new cliprect now.
 534     *
 535     * NOTE: This releases and regains the hw lock, so all state
 536     * checking must be done *after* this call:
 537     */
 538    DRI_VALIDATE_DRAWABLE_INFO( sPriv, dPriv);
 539
 540    /* If we lost context, need to dump all registers to hardware.
 541     * Note that we don't care about 2d contexts, even if they perform
 542     * accelerated commands, so the DRI locking in the X server is even
 543     * more broken than usual.
 544     */
 545
 546    if (sarea->ctxOwner != me) {
 547       imesa->upload_cliprects = GL_TRUE;
 548       imesa->dirty |= (I830_UPLOAD_CTX |
 549                        I830_UPLOAD_BUFFERS |
 550                        I830_UPLOAD_STIPPLE);
 551
 552       if(imesa->CurrentTexObj[0]) imesa->dirty |= I830_UPLOAD_TEX0;
 553       if(imesa->CurrentTexObj[1]) imesa->dirty |= I830_UPLOAD_TEX1;
 554       if(imesa->TexBlendWordsUsed[0]) imesa->dirty |= I830_UPLOAD_TEXBLEND0;
 555       if(imesa->TexBlendWordsUsed[1]) imesa->dirty |= I830_UPLOAD_TEXBLEND1;
 556
 557       sarea->perf_boxes = imesa->perf_boxes | I830_BOX_LOST_CONTEXT;
 558       sarea->ctxOwner = me;
 559    }
 560
 561    /* Shared texture managment - if another client has played with
 562     * texture space, figure out which if any of our textures have been
 563     * ejected, and update our global LRU.
 564     */
 565
 566    for ( i = 0 ; i < imesa->nr_heaps ; i++ ) {
 567       DRI_AGE_TEXTURES( imesa->texture_heaps[ i ] );
 568    }
 569
 570    if (imesa->lastStamp != dPriv->lastStamp) {
 571       i830XMesaWindowMoved( imesa );
 572       imesa->lastStamp = dPriv->lastStamp;
 573    }
 574
 575    sarea->last_quiescent = -1;  /* just kill it for now */
 576 }
 577
 578 void i830SwapBuffers( __DRIdrawablePrivate *dPriv )
 579 {
 580    if (dPriv->driContextPriv && dPriv->driContextPriv->driverPrivate) {
 581       i830ContextPtr imesa;
 582       GLcontext *ctx;
 583       imesa = (i830ContextPtr) dPriv->driContextPriv->driverPrivate;
 584       ctx = imesa->glCtx;
 585       if (ctx->Visual.doubleBufferMode) {
 586          _mesa_notifySwapBuffers( ctx );  /* flush pending rendering comands */
 587          if ( 0 /*imesa->doPageFlip*/ ) { /* doPageFlip is never set !!! */
 588             i830PageFlip( dPriv );
 589          } else {
 590             i830CopyBuffer( dPriv );
 591          }
 592       }
 593    } else {
 594       /* XXX this shouldn't be an error but we can't handle it for now */
 595       _mesa_problem(NULL, "%s: drawable has no context!\n", __FUNCTION__);
 596    }
 597 }