dri2proto.txt revision d63b911f
1 The DRI2 Extension 2 Version 2.0 3 2008-09-04 4 5 Kristian Høgsberg 6 krh@redhat.com 7 Red Hat, Inc 8 9 101. Introduction 11 12The DRI2 extension is designed to associate and access auxiliary 13rendering buffers with an X drawable. 14 15DRI2 is a essentially a helper extension to support implementation of 16direct rendering drivers/libraries/technologies. 17 18The main consumer of this extension will be a direct rendering OpenGL 19driver, but the DRI2 extension is not designed to be OpenGL specific. 20Direct rendering implementations of OpenVG, Xv, cairo and other 21graphics APIs should find the functionality exposed by this extension 22helpful and hopefully sufficient. 23 24Relation to XF86DRI 25 26 271.1. Acknowledgements 28 29Kevin E. Martin <kem@redhat.com> 30Keith Packard <keithp@keithp.com> 31Eric Anholt <eric@anholt.net> 32Keith Whitwell <keith@tungstengraphics.com> 33Jerome Glisse <glisse@freedesktop.org> 34Ian Romanick <ian.d.romanick@intel.com> 35Michel Dänzer <michel@tungstengraphics.com> 36Jesse Barnes <jbarnes@virtuousgeek.org> 37 38 39 ⚙ ⚙ ⚙ ⚙ ⚙ ⚙ 40 41 422. DRI2 Concepts 43 44 452.1. Attachment points 46 47Stolen from OpenGL FBOs, I guess. 48 49 502.2. Kernel rendering manager 51 52This specification assumes a rendering architecture, where an 53underlying kernel rendering manager that can provide 32 bit integer 54handles to video memory buffers. These handles can be passed between 55processes, which, through a direct rendering driver, submit rendering 56to the kernel rendering manager, targeting and/or sourcing from these 57buffers. This extension provides a means to communicate about such 58buffers as associated with an X drawable. 59 60The details of how the direct rendering driver use the buffer names 61and submit the rendering requests is outside the scope of this 62specification. However, Appendix B does discuss implementation of 63this specification on the Graphics Execution Manager (GEM). 64 65 662.3. Request ordering 67 68No ordering between swap buffers and X rendering. X rendering to src 69buffers will block if they have a vblank pending. 70 71 722.4 Authentication model 73 74The purpose of the DRM authentication scheme is to grant access to the 75kernel rendering manager buffers created by the X server if, and only 76if, the client has access to the X server. This is achieved in a 77three-step protocol: 78 79 1) The client gets a token from the kernel rendering manager 80 that uniquely identifies it. The token is a 32 bit integer. 81 82 2) The client passes the token to the X server in the 83 DRI2Authenticate request. This request is a round trip to 84 make sure the X server has received and processed the 85 authentication before the client starts accessing the DRM. 86 87 3) The X server authorizes the client by passing the token to 88 the kernel rendering manager. 89 90A kernel rendering manager can choose not to implement any 91authentication and just allow access to all buffers. 92 93 942.5 Rendering to the X front buffer 95 96OpenGL allows the client to render to the front buffer, either by 97using a single-buffered configuration or but explicitly setting the 98draw buffer to GL_FRONT_LEFT. Not allowed! 99 100The client must ask for a fake front buffer, render to that and then 101use DRI2CopyRegion to copy contents back and forth between the fake 102front buffer and the real front buffer. When X and direct rendering 103to a front buffer is interleaved, it is the responsibility of the 104application to synchronize access using glXWaitGL and glXWaitX. A 105DRI2 implementation of direct rendering GLX, should use these entry 106points to copy contents back and forth to as necessary to ensure 107consistent rendering. 108 109The client may also use the DRI2SwapBuffers function to request a swap 110of the front and back buffers. If the display server supports it, this 111operation may be preferred, since it may be easier and/or more performant 112for the server to perform a simple buffer swap rather than a blit. 113 1142.6 Synchronizing rendering 115 116DRI2 provides several methods for synchronizing drawing with various events. 117The protocol for these methods is based on the SGI_video_sync and 118OML_sync_control GLX extensions. Using the DRI2WaitMSC request, a client 119can wait for a specific frame count or divisor/remainder before continuing 120its processing. With the DRI2WaitSBC request, clients can block until a given 121swap count is reached (as incremented by DRI2SwapBuffers). Finally, using 122DRI2SwapBuffers, clients can limit their frame rate by specifying a swap 123interval using the swap interval call (currently only available through GLX) 124or by using the OML swap buffers routine. 125 1262.7 Events 127 128DRI2 provides an event to indicate when a DRI2SwapBuffers request has 129been completed. This can be used to throttle drawing on the client 130side and tie into application main loops. 131 132Another event is generated when the validity of the requested buffers 133changes. 134 135 ⚙ ⚙ ⚙ ⚙ ⚙ ⚙ 136 137 1383. Data Types 139 140The server side region support specified in the Xfixes extension 141version 2 is used in the CopyRegion request. 142 143 144 ⚙ ⚙ ⚙ ⚙ ⚙ ⚙ 145 146 1474. Errors 148 149No errors are defined by the DRI2 extension. 150 151 152 ⚙ ⚙ ⚙ ⚙ ⚙ ⚙ 153 1545. Events 155 156The only events provided by DRI2 are DRI2_BufferSwapComplete 157and DRI2InvalidateBuffers. 158 159 160 ⚙ ⚙ ⚙ ⚙ ⚙ ⚙ 161 162 1636. Protocol Types 164 165DRI2DRIVER { DRI2DriverDRI 166 DRI2DriverVDPAU } 167 168 These values describe the type of driver the client will want 169 to load. The server sends back the name of the driver to use 170 for the screen in question. 171 172DRI2ATTACHMENT { DRI2BufferFrontLeft 173 DRI2BufferBackLeft 174 DRI2BufferFrontRight 175 DRI2BufferBackRight 176 DRI2BufferDepth 177 DRI2BufferStencil 178 DRI2BufferAccum 179 DRI2BufferFakeFrontLeft 180 DRI2BufferFakeFrontRight 181 DRI2BufferDepthStencil 182 DRI2BufferHiz } 183 184 These values describe various attachment points for DRI2 185 buffers. 186 187DRI2BUFFER { attachment: CARD32 188 name: CARD32 189 pitch: CARD32 190 cpp: CARD32 191 flags: CARD32 } 192 193 The DRI2BUFFER describes an auxiliary rendering buffer 194 associated with an X drawable. 'attachment' describes the 195 attachment point for the buffer, 'name' is the name of the 196 underlying kernel buffer, 197 198 199DRI2ATTACH_FORMAT { attachment: CARD32 200 format: CARD32 } 201 202 The DRI2ATTACH_FORMAT describes an attachment and the associated 203 format. 'attachment' describes the attachment point for the buffer, 204 'format' describes an opaque, device-dependent format for the buffer. 205 206 ⚙ ⚙ ⚙ ⚙ ⚙ ⚙ 207 208 2097. Extension Initialization 210 211The name of this extension is "DRI2". 212 213┌─── 214 DRI2QueryVersion 215 client-major-version: CARD32 216 client-minor-version: CARD32 217 ▶ 218 major-version: CARD32 219 minor-version: CARD32 220└─── 221 222 The client sends the highest supported version to the server 223 and the server sends the highest version it supports, but no 224 higher than the requested version. Major versions changes can 225 introduce incompatibilities in existing functionality, minor 226 version changes introduce only backward compatible changes. 227 It is the clients responsibility to ensure that the server 228 supports a version which is compatible with its expectations. 229 230 Backwards compatible changes included addition of new 231 requests, but also new value types in the DRI2CopyRegion 232 request. When new values are introduced, the minor version 233 will be increased so the client can know which values the X 234 server understands from the version number. 235 236 237 ⚙ ⚙ ⚙ ⚙ ⚙ ⚙ 238 239 2408. Extension Requests 241 242┌─── 243 DRI2Connect 244 window: WINDOW 245 driverType: DRI2DRIVER 246 ▶ 247 driver: STRING 248 device: STRING 249└─── 250 251 Returns the driver name and device file to use for the 252 specified driver type for the screen associated with 'window'. 253 254 'type' identifies the type of driver to query for. 255 256 'driver' is the name of the driver to load. The client is 257 assumed to know where to look for the drivers and what to do 258 with it. 259 260 'device' is the filename of the DRM device file. 261 262 If the client is not local, or the request driver type is 263 unknown or not available, 'driver' and 'device' will be empty 264 strings. We are not using an regular X 265 error here to indicate failure, which will allow the client 266 fall back to other options more easily. 267 268 ISSUE: We could add the list of supported attachments and the 269 supported DRI2CopyRegion values here (just the bitmask of all 270 supported values). 271 272┌─── 273 DRI2Authenticate 274 window: WINDOW 275 token: CARD32 276 ▶ 277 authenticated: CARD32 278└─── 279 Errors: Window 280 281 Request that the X server authenticates 'token', allowing the 282 client to access the DRM buffers created by the X server on 283 the screen associated with 'window'. 284 285 Authentication shouldn't fail at this point, except if an 286 invalid token is passed, in which case authenticated is False. 287 288┌─── 289 DRI2GetBuffers 290 drawable: DRAWABLE 291 attachments: LISTofDRI2ATTACHMENTS 292 ▶ 293 width, height: CARD32 294 buffers: LISTofDRI2BUFFER 295└─── 296 Errors: Window 297 298 Get buffers for the provided attachment points for the given 299 drawable. 300 301 If the DDX driver does not support one or more of the 302 specified attachment points, a Value error is generated, with 303 the first unsupported attachment point as the error value. 304 305 'width' and 'height' describes the dimensions of the drawable. 306 307 'buffers' is a list of DRI2BUFFER for the given DRI2 308 attachment points. 309 310┌─── 311 DRI2CopyRegion 312 drawable: DRAWABLE 313 region: REGION 314 source: DRI2ATTACHMENT 315 destination: DRI2ATTACHMENT 316 ▶ 317└─── 318 Errors: Window, Value 319 320 Schedule a copy from one DRI2 buffer to another. 321 322 The DRICopyRegion request has a reply but it is empty. The 323 reply is there to let the direct rendering client wait until 324 the server has seen the request before proceeding with 325 rendering the next frame. 326 327┌─── 328 DRI2SwapBuffers 329 drawable: DRAWABLE 330 target_msc: two CARD32s 331 divisor: two CARD32s 332 remainder: two CARD32s 333 ▶ 334 swap: two CARD32s 335└─── 336 Errors: Window 337 338 Schedule a swap of the front and back buffers with the display 339 server. 340 341 Returns the swap count value when the swap will actually occur (e.g. 342 the last queued swap count + (pending swap count * swap interval)). 343 344 This request is only available with protocol version 1.2 or 345 later. 346 347┌─── 348 DRI2GetBuffersWithFormat 349 drawable: DRAWABLE 350 attachments: LISTofDRI2ATTACH_FORMAT 351 ▶ 352 width, height: CARD32 353 buffers: LISTofDRI2BUFFER 354└─── 355 Errors: Window 356 357 Get buffers for the provided attachment points with the specified 358 formats for the given drawable. 359 360 If the DDX driver does not support one or more of the 361 specified attachment points or formats, a Value error is generated, 362 with the first unsupported attachment point as the error value. 363 364 'width' and 'height' describes the dimensions of the drawable. 365 366 'buffers' is a list of DRI2BUFFER for the given DRI2 367 attachment points. 368 369 This request is only available with protocol version 1.1 or 370 later. 371 372┌─── 373 DRI2GetMSC 374 drawable: DRAWABLE 375 ▶ 376 ust, msc, sbc: CARD64 377└─── 378 Errors: Window 379 380 Get the current media stamp counter (MSC) and swap buffer count (SBC) 381 along with the unadjusted system time (UST) when the MSC was last 382 incremented. 383 384 This request is only available with protocol version 1.2 or 385 later. 386 387┌─── 388 DRI2WaitMSC 389 drawable: DRAWABLE 390 target_msc: two CARD32s 391 divisor: two CARD32s 392 remainder: two CARD32s 393 ▶ 394 ust, msc, sbc: CARD64 395└─── 396 Errors: Window 397 398 Blocks the client until either the frame count reaches target_msc or, 399 if the frame count is already greater than target_msc when the request 400 is received, until the frame count % divisor = remainder. If divisor 401 is 0, the client will be unblocked if the frame count is greater than 402 or equal to the target_msc. 403 404 Returns the current media stamp counter (MSC) and swap buffer count 405 (SBC) along with the unadjusted system time (UST) when the MSC was last 406 incremented. 407 408 This request is only available with protocol version 1.2 or 409 later. 410 411┌─── 412 DRI2WaitSBC 413 drawable: DRAWABLE 414 target_sbc: two CARD32s 415 ▶ 416 ust, msc, sbc: CARD64 417└─── 418 Errors: Window 419 420 Blocks the client until the swap buffer count reaches target_sbc. If 421 the swap buffer count is already greater than or equal to target_sbc 422 when the request is received, this request will return immediately. 423 424 If target_sbc is 0, this request will block the client until all 425 previous DRI2SwapBuffers requests have completed. 426 427 Returns the current media stamp counter (MSC) and swap buffer count 428 (SBC) along with the unadjusted system time (UST) when the MSC was last 429 incremented. 430 431 This request is only available with protocol version 1.2 or 432 later. 433 434┌─── 435 DRI2SwapInterval 436 drawable: DRAWABLE 437 interval: CARD32 438 ▶ 439└─── 440 Errors: Window 441 442 Sets the swap interval for DRAWABLE. This will throttle 443 DRI2SwapBuffers requests to swap at most once per interval frames, 444 which is useful useful for limiting the frame rate. 445 446┌─── 447 DRI2GetParam 448 drawable: DRAWABLE 449 param: CARD32 450 ▶ 451 is_param_recognized: BOOL 452 value: CARD64 453└─── 454 Errors: Drawable 455 456 Get the value of a parameter. The parameter's value is looked up on 457 the screen associated with 'drawable'. 458 459 Parameter names in which the value of the most significant byte is 460 0 are reserved for the X server. Currently, no such parameter names 461 are defined. (When any such names are defined, they will be defined in 462 this extension specification and its associated headers). 463 464 Parameter names in which the byte's value is 1 are reserved for the 465 DDX. Such names are private to each driver and shall be defined in the 466 respective driver's headers. 467 468 Parameter names in which the byte's value is neither 0 nor 1 are 469 reserved for future use. 470 471 Possible values of 'is_param_recognized' are true (1) and false (0). 472 If false, then 'value' is undefined. 473 474 This request is only available with protocol version 1.4 or later. 475 476 ⚙ ⚙ ⚙ ⚙ ⚙ ⚙ 477 4789. Extension Events 479 480┌─── 481 DRI2BufferSwapComplete 482 ▶ 483 event_type: CARD16 484 drawable: CARD32 485 ust: CARD64 486 msc: CARD64 487 sbc: CARD64 488└─── 489 490 This event reports the status of the last DRI2SwapBuffers event to 491 the client. The event type should be one of DRI2_EXCHANGE_COMPLETE, 492 indicating a successful buffer exchange, DRI2_BLIT_COMPLETE, indicating 493 the swap was performed with a blit, and DRI2_FLIP_COMPLETE, indicating 494 a full page flip was completed. 495 496┌─── 497 DRI2InvalidateBuffers 498 ▶ 499 drawable: CARD32 500└─── 501 502 This event is generated when the buffers the client had 503 requested for 'drawable' (with DRI2GetBuffers or 504 DRI2GetBuffersWithFormat) become inappropriate because they 505 don't match the drawable dimensions anymore, or a buffer swap 506 has been performed. 507 508 Note that the server is only required to warn the client once 509 about this condition, until the client takes care of bringing 510 them back up-to-date with another GetBuffers request. 511 512 ⚙ ⚙ ⚙ ⚙ ⚙ ⚙ 513 51410. Extension Versioning 515 516The DRI2 extension has undergone a number of revisions before 517 518 1.0: Released, but never used. Relied on a number of 519 constructs from the XF86DRI extension, such as a 520 shared memory area (SAREA) to communicate changes in 521 cliprects and window sizes, and 522 523 1.99.1: Move the swap buffer functionality into the X server, 524 introduce SwapBuffer request to copy back buffer 525 contents to the X drawable. 526 527 1.99.2: Rethink the SwapBuffer request as an asynchronous 528 request to copy a region between DRI2 buffers. Drop 529 CreateDrawable and DestroyDrawable, update Connect to 530 support different driver types and to send the 531 authentication group. 532 533 1.99.3: Drop the bitmask argument intended to indicate 534 presence of optional arguments for CopyRegion. 535 536 2.0: Awesomeness! 537 538 2.1: True excellence. Added DRI2GetBuffersWithFormat to allow 539 more flexible object creation. 540 541 2.2: Approaching perfection. Added requests for swapbuffers, 542 MSC and SBC related requests, and events. 543 544 2.3: Added the DRI2InvalidateBuffers event. 545 546 2.6: Enlightenment attained. Added the DRI2BufferHiz attachment. 547 548 2.7: Added the DRI2GetParam request. 549 550Compatibility up to 2.0 is not preserved, but was also never released. 551 552 553 ⚙ ⚙ ⚙ ⚙ ⚙ ⚙ 554 555 55611. Relationship with other extensions 557 558As an extension designed to support other extensions, there is 559naturally some interactions with other extensions. 560 561 56211.1 GLX 563 564The GL auxiliary buffers map directly to the DRI2 buffers... eh 565 566 56711.2 DBE 568 569The DBE back buffer must correspond to the DRI2_BUFFER_FRONT_LEFT 570DRI2 buffer for servers that support both DBE and DRI2. 571 572 57311.3 XvMC / Xv 574 575We might add a DRI2_BUFFER_YUV to do vsynced colorspace conversion 576blits. Maybe... not really sure. 577 578 579 ⚙ ⚙ ⚙ ⚙ ⚙ ⚙ 580 581 582Appendix A. Protocol Encoding 583 584Syntactic Conventions 585 586This document uses the same syntactic conventions as the core X 587protocol encoding document. 588 589 590A.1 Common Types 591 592┌─── 593 DRI2DRIVER 594 0x0 DRI2DriverDRI 595 0x1 DRI2DriverVDPAU 596└─── 597 598┌─── 599 DRI2ATTACHMENT 600 0x0 DRI2BufferFrontLeft 601 0x1 DRI2BufferBackLeft 602 0x2 DRI2BufferFrontRight 603 0x3 DRI2BufferBackRight 604 0x4 DRI2BufferDepth 605 0x5 DRI2BufferStencil 606 0x6 DRI2BufferAccum 607 0x7 DRI2BufferFakeFrontLeft 608 0x8 DRI2BufferFakeFrontRight 609 0x9 DRI2BufferDepthStencil 610 0xa DRI2BufferHiz 611└─── 612 Used to encode the possible attachment points. The attachment 613 DRI2BufferDepthStencil is only available with protocol version 1.1 or 614 later. 615 616┌─── 617 DRI2BUFFER 618 4 CARD32 attachment 619 4 CARD32 name 620 4 CARD32 pitch 621 4 CARD32 cpp 622 4 CARD32 flags 623└─── 624 A DRI2 buffer specifies the attachment, the kernel memory 625 manager name, the pitch and chars per pixel for a buffer 626 attached to a given drawable. 627 628┌─── 629 DRI2ATTACH_FORMAT 630 4 CARD32 attachment 631 4 CARD32 format 632└─── 633 Used to describe the attachment and format requested from the server. 634 This data type is only available with protocol version 1.1 or 635 later. 636 637A.2 Protocol Requests 638 639┌─── 640 DRI2QueryVersion 641 1 CARD8 major opcode 642 1 0 DRI2 opcode 643 2 3 length 644 4 CARD32 major version 645 4 CARD32 minor version 646 ▶ 647 1 1 Reply 648 1 unused 649 2 CARD16 sequence number 650 4 0 reply length 651 4 CARD32 major version 652 4 CARD32 minor version 653 16 unused 654└─── 655 656┌─── 657 DRI2Connect 658 1 CARD8 major opcode 659 1 1 DRI2 opcode 660 2 3 length 661 4 WINDOW window 662 4 CARD32 driver type 663 ▶ 664 1 1 Reply 665 1 unused 666 2 CARD16 sequence number 667 4 (n+m+p+q)/4 reply length 668 4 n driver name length 669 4 m device name length 670 16 unused 671 n CARD8 driver name 672 p unused, p=pad(n) 673 m CARD8 device name 674 q unused, q=pad(m) 675└─── 676 677┌─── 678 DRI2Authenticate 679 1 CARD8 major opcode 680 1 2 DRI2 opcode 681 2 3 length 682 4 WINDOW window 683 4 CARD32 authentication token 684 ▶ 685 1 1 Reply 686 1 unused 687 2 CARD16 sequence number 688 4 0 reply length 689 4 CARD32 authenticated 690 20 unused 691└─── 692 693┌─── 694 DRI2GetBuffers 695 1 CARD8 major opcode 696 1 5 DRI2 opcode 697 2 3 length 698 4 DRAWABLE drawable 699 4 n number of attachments 700 4n LISTofDRI2ATTACHMENTS attachments 701 ▶ 702 1 1 Reply 703 1 unused 704 2 CARD16 sequence number 705 4 0 reply length 706 4 CARD32 width of drawable 707 4 CARD32 height of drawable 708 4 CARD32 buffer count 709 12 unused 710 5n LISTofDRI2BUFFER buffers 711└─── 712 713┌─── 714 DRI2CopyRegion 715 1 CARD8 major opcode 716 1 6 DRI2 opcode 717 2 3 length 718 4 DRAWABLE drawable 719 4 REGION region 720 4 DRI2ATTACHMENT source 721 4 DRI2ATTACHMENT destination 722 ▶ 723 1 1 Reply 724 1 unused 725 2 CARD16 sequence number 726 4 0 reply length 727 24 unused 728└─── 729 730┌─── 731 DRI2GetBuffersWithFormat 732 1 CARD8 major opcode 733 1 7 DRI2 opcode 734 2 3 length 735 4 DRAWABLE drawable 736 4 n number of attachments 737 8n LISTofDRI2ATTACH_FORMAT attachments and formats 738 ▶ 739 1 1 Reply 740 1 unused 741 2 CARD16 sequence number 742 4 0 reply length 743 4 CARD32 width of drawable 744 4 CARD32 height of drawable 745 4 CARD32 buffer count 746 12 unused 747 5n LISTofDRI2BUFFER buffers 748└─── 749 750┌─── 751 DRI2SwapBuffers 752 1 CARD8 major opcode 753 1 8 DRI2 opcode 754 2 8 length 755 4 DRAWABLE drawable 756 4 CARD32 target_msc_hi 757 4 CARD32 target_msc_lo 758 4 CARD32 divisor_hi 759 4 CARD32 divisor_lo 760 4 CARD32 remainder_hi 761 4 CARD32 remainder_lo 762 ▶ 763 1 1 Reply 764 1 unused 765 2 CARD16 sequence number 766 4 0 reply length 767 4 CARD32 swap_hi 768 4 CARD32 swap_lo 769 20 unused 770└─── 771 772┌─── 773 DRI2GetMSC 774 1 CARD8 major opcode 775 1 9 DRI2 opcode 776 2 8 length 777 4 DRAWABLE drawable 778 ▶ 779 1 1 Reply 780 1 unused 781 2 CARD16 sequence number 782 4 0 reply length 783 4 CARD32 ust_hi 784 4 CARD32 ust_lo 785 4 CARD32 msc_hi 786 4 CARD32 msc_lo 787 4 CARD32 sbc_hi 788 4 CARD32 sbc_lo 789└─── 790 791┌─── 792 DRI2WaitMSC 793 1 CARD8 major opcode 794 1 10 DRI2 opcode 795 2 8 length 796 4 DRAWABLE drawable 797 4 CARD32 target_msc_hi 798 4 CARD32 target_msc_lo 799 4 CARD32 divisor_hi 800 4 CARD32 divisor_lo 801 4 CARD32 remainder_hi 802 4 CARD32 remainder_lo 803 ▶ 804 1 1 Reply 805 1 unused 806 2 CARD16 sequence number 807 4 0 reply length 808 4 CARD32 ust_hi 809 4 CARD32 ust_lo 810 4 CARD32 msc_hi 811 4 CARD32 msc_lo 812 4 CARD32 sbc_hi 813 4 CARD32 sbc_lo 814└─── 815 816┌─── 817 DRI2WaitSBC 818 1 CARD8 major opcode 819 1 11 DRI2 opcode 820 2 8 length 821 4 DRAWABLE drawable 822 4 CARD32 swap_hi 823 4 CARD32 swap_lo 824 ▶ 825 1 1 Reply 826 1 unused 827 2 CARD16 sequence number 828 4 0 reply length 829 4 CARD32 ust_hi 830 4 CARD32 ust_lo 831 4 CARD32 msc_hi 832 4 CARD32 msc_lo 833 4 CARD32 sbc_hi 834 4 CARD32 sbc_lo 835└─── 836 837┌─── 838 DRI2SwapInterval 839 1 CARD8 major opcode 840 1 12 DRI2 opcode 841 2 8 length 842 4 DRAWABLE drawable 843 4 CARD32 interval 844 ▶ 845└─── 846 847┌─── 848 DRI2GetParam 849 1 CARD8 major opcode 850 1 13 DRI2 opcode 851 2 8 length 852 4 DRAWABLE drawable 853 4 CARD32 param 854 ▶ 855 1 1 Reply 856 1 BOOL is_param_recognized 857 2 CARD16 sequence number 858 4 0 reply length 859 4 CARD32 value_hi 860 4 CARD32 value_lo 861 16 unused 862└─── 863 864A.3 Protocol Events 865 866The DRI2 extension specifies DRI2_BufferSwapComplete and 867DRI2_InvalidateBuffers events. 868 869┌─── 870 DRI2_BufferSwapComplete 871 1 CARD8 type 872 1 CARD8 extension 873 2 CARD16 sequenceNumber 874 2 CARD16 event_type 875 4 DRAWABLE drawable 876 4 CARD32 ust_hi 877 4 CARD32 ust_lo 878 4 CARD32 msc_hi 879 4 CARD32 msc_lo 880 4 CARD32 sbc_hi 881 4 CARD32 sbc_lo 882└─── 883 884 885┌─── 886 DRI2_InvalidateBuffers 887 1 CARD8 type 888 1 CARD8 extension 889 2 CARD16 sequenceNumber 890 4 DRAWABLE drawable 891 4 CARD32 unused 892 4 CARD32 unused 893 4 CARD32 unused 894 4 CARD32 unused 895 4 CARD32 unused 896 4 CARD32 unused 897└─── 898 899A.4 Protocol Errors 900 901The DRI2 extension specifies no errors. 902 903 904 ⚙ ⚙ ⚙ ⚙ ⚙ ⚙ 905 906 907Appendix B. Implementation on GEM 908 909Where to begin... 910