source: vbox/trunk/src/VBox/Devices/Graphics/vmsvga/svga_reg.h@ 52970

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 *
 * Permission is hereby granted, free of charge, to any person
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/*
 * svga_reg.h --
 *
 *    Virtual hardware definitions for the VMware SVGA II device.
 */

#ifndef _SVGA_REG_H_
#define _SVGA_REG_H_

/*
 * PCI device IDs.
 */
#define PCI_VENDOR_ID_VMWARE            0x15AD
#define PCI_DEVICE_ID_VMWARE_SVGA2      0x0405

/*
 * SVGA_REG_ENABLE bit definitions.
 */
#define SVGA_REG_ENABLE_DISABLE     0
#define SVGA_REG_ENABLE_ENABLE      1
#define SVGA_REG_ENABLE_HIDE        2
#define SVGA_REG_ENABLE_ENABLE_HIDE (SVGA_REG_ENABLE_ENABLE |\
                                     SVGA_REG_ENABLE_HIDE)

/*
 * Legal values for the SVGA_REG_CURSOR_ON register in old-fashioned
 * cursor bypass mode. This is still supported, but no new guest
 * drivers should use it.
 */
#define SVGA_CURSOR_ON_HIDE            0x0   /* Must be 0 to maintain backward compatibility */
#define SVGA_CURSOR_ON_SHOW            0x1   /* Must be 1 to maintain backward compatibility */
#define SVGA_CURSOR_ON_REMOVE_FROM_FB  0x2   /* Remove the cursor from the framebuffer because we need to see what's under it */
#define SVGA_CURSOR_ON_RESTORE_TO_FB   0x3   /* Put the cursor back in the framebuffer so the user can see it */

/*
 * The maximum framebuffer size that can traced for e.g. guests in VESA mode.
 * The changeMap in the monitor is proportional to this number. Therefore, we'd
 * like to keep it as small as possible to reduce monitor overhead (using
 * SVGA_VRAM_MAX_SIZE for this increases the size of the shared area by over
 * 4k!).
 *
 * NB: For compatibility reasons, this value must be greater than 0xff0000.
 *     See bug 335072.
 */
#define SVGA_FB_MAX_TRACEABLE_SIZE      0x1000000

#define SVGA_MAX_PSEUDOCOLOR_DEPTH      8
#define SVGA_MAX_PSEUDOCOLORS           (1 << SVGA_MAX_PSEUDOCOLOR_DEPTH)
#define SVGA_NUM_PALETTE_REGS           (3 * SVGA_MAX_PSEUDOCOLORS)

#define SVGA_MAGIC         0x900000UL
#define SVGA_MAKE_ID(ver)  (SVGA_MAGIC << 8 | (ver))

/* Version 2 let the address of the frame buffer be unsigned on Win32 */
#define SVGA_VERSION_2     2
#define SVGA_ID_2          SVGA_MAKE_ID(SVGA_VERSION_2)

/* Version 1 has new registers starting with SVGA_REG_CAPABILITIES so
   PALETTE_BASE has moved */
#define SVGA_VERSION_1     1
#define SVGA_ID_1          SVGA_MAKE_ID(SVGA_VERSION_1)

/* Version 0 is the initial version */
#define SVGA_VERSION_0     0
#define SVGA_ID_0          SVGA_MAKE_ID(SVGA_VERSION_0)

/* "Invalid" value for all SVGA IDs. (Version ID, screen object ID, surface ID...) */
#define SVGA_ID_INVALID    0xFFFFFFFF

/* Port offsets, relative to BAR0 */
#define SVGA_INDEX_PORT         0x0
#define SVGA_VALUE_PORT         0x1
#define SVGA_BIOS_PORT          0x2
#define SVGA_IRQSTATUS_PORT     0x8

/*
 * Interrupt source flags for IRQSTATUS_PORT and IRQMASK.
 *
 * Interrupts are only supported when the
 * SVGA_CAP_IRQMASK capability is present.
 */
#define SVGA_IRQFLAG_ANY_FENCE            0x1    /* Any fence was passed */
#define SVGA_IRQFLAG_FIFO_PROGRESS        0x2    /* Made forward progress in the FIFO */
#define SVGA_IRQFLAG_FENCE_GOAL           0x4    /* SVGA_FIFO_FENCE_GOAL reached */

/*
 * Registers
 */

enum {
   SVGA_REG_ID = 0,
   SVGA_REG_ENABLE = 1,
   SVGA_REG_WIDTH = 2,
   SVGA_REG_HEIGHT = 3,
   SVGA_REG_MAX_WIDTH = 4,
   SVGA_REG_MAX_HEIGHT = 5,
   SVGA_REG_DEPTH = 6,
   SVGA_REG_BITS_PER_PIXEL = 7,       /* Current bpp in the guest */
   SVGA_REG_PSEUDOCOLOR = 8,
   SVGA_REG_RED_MASK = 9,
   SVGA_REG_GREEN_MASK = 10,
   SVGA_REG_BLUE_MASK = 11,
   SVGA_REG_BYTES_PER_LINE = 12,
   SVGA_REG_FB_START = 13,            /* (Deprecated) */
   SVGA_REG_FB_OFFSET = 14,
   SVGA_REG_VRAM_SIZE = 15,
   SVGA_REG_FB_SIZE = 16,

   /* ID 0 implementation only had the above registers, then the palette */

   SVGA_REG_CAPABILITIES = 17,
   SVGA_REG_MEM_START = 18,           /* (Deprecated) */
   SVGA_REG_MEM_SIZE = 19,
   SVGA_REG_CONFIG_DONE = 20,         /* Set when memory area configured */
   SVGA_REG_SYNC = 21,                /* See "FIFO Synchronization Registers" */
   SVGA_REG_BUSY = 22,                /* See "FIFO Synchronization Registers" */
   SVGA_REG_GUEST_ID = 23,            /* Set guest OS identifier */
   SVGA_REG_CURSOR_ID = 24,           /* (Deprecated) */
   SVGA_REG_CURSOR_X = 25,            /* (Deprecated) */
   SVGA_REG_CURSOR_Y = 26,            /* (Deprecated) */
   SVGA_REG_CURSOR_ON = 27,           /* (Deprecated) */
   SVGA_REG_HOST_BITS_PER_PIXEL = 28, /* (Deprecated) */
   SVGA_REG_SCRATCH_SIZE = 29,        /* Number of scratch registers */
   SVGA_REG_MEM_REGS = 30,            /* Number of FIFO registers */
   SVGA_REG_NUM_DISPLAYS = 31,        /* (Deprecated) */
   SVGA_REG_PITCHLOCK = 32,           /* Fixed pitch for all modes */
   SVGA_REG_IRQMASK = 33,             /* Interrupt mask */

   /* Legacy multi-monitor support */
   SVGA_REG_NUM_GUEST_DISPLAYS = 34,/* Number of guest displays in X/Y direction */
   SVGA_REG_DISPLAY_ID = 35,        /* Display ID for the following display attributes */
   SVGA_REG_DISPLAY_IS_PRIMARY = 36,/* Whether this is a primary display */
   SVGA_REG_DISPLAY_POSITION_X = 37,/* The display position x */
   SVGA_REG_DISPLAY_POSITION_Y = 38,/* The display position y */
   SVGA_REG_DISPLAY_WIDTH = 39,     /* The display's width */
   SVGA_REG_DISPLAY_HEIGHT = 40,    /* The display's height */

   /* See "Guest memory regions" below. */
   SVGA_REG_GMR_ID = 41,
   SVGA_REG_GMR_DESCRIPTOR = 42,
   SVGA_REG_GMR_MAX_IDS = 43,
   SVGA_REG_GMR_MAX_DESCRIPTOR_LENGTH = 44,

   SVGA_REG_TRACES = 45,            /* Enable trace-based updates even when FIFO is on */
   SVGA_REG_GMRS_MAX_PAGES = 46,    /* Maximum number of 4KB pages for all GMRs */
   SVGA_REG_MEMORY_SIZE = 47,       /* Total dedicated device memory excluding FIFO */
   SVGA_REG_TOP = 48,               /* Must be 1 more than the last register */

   SVGA_PALETTE_BASE = 1024,        /* Base of SVGA color map */
   /* Next 768 (== 256*3) registers exist for colormap */

   SVGA_SCRATCH_BASE = SVGA_PALETTE_BASE + SVGA_NUM_PALETTE_REGS
                                    /* Base of scratch registers */
   /* Next reg[SVGA_REG_SCRATCH_SIZE] registers exist for scratch usage:
      First 4 are reserved for VESA BIOS Extension; any remaining are for
      the use of the current SVGA driver. */
};


/*
 * Guest memory regions (GMRs):
 *
 * This is a new memory mapping feature available in SVGA devices
 * which have the SVGA_CAP_GMR bit set. Previously, there were two
 * fixed memory regions available with which to share data between the
 * device and the driver: the FIFO ('MEM') and the framebuffer. GMRs
 * are our name for an extensible way of providing arbitrary DMA
 * buffers for use between the driver and the SVGA device. They are a
 * new alternative to framebuffer memory, usable for both 2D and 3D
 * graphics operations.
 *
 * Since GMR mapping must be done synchronously with guest CPU
 * execution, we use a new pair of SVGA registers:
 *
 *   SVGA_REG_GMR_ID --
 *
 *     Read/write.
 *     This register holds the 32-bit ID (a small positive integer)
 *     of a GMR to create, delete, or redefine. Writing this register
 *     has no side-effects.
 *
 *   SVGA_REG_GMR_DESCRIPTOR --
 *
 *     Write-only.
 *     Writing this register will create, delete, or redefine the GMR
 *     specified by the above ID register. If this register is zero,
 *     the GMR is deleted. Any pointers into this GMR (including those
 *     currently being processed by FIFO commands) will be
 *     synchronously invalidated.
 *
 *     If this register is nonzero, it must be the physical page
 *     number (PPN) of a data structure which describes the physical
 *     layout of the memory region this GMR should describe. The
 *     descriptor structure will be read synchronously by the SVGA
 *     device when this register is written. The descriptor need not
 *     remain allocated for the lifetime of the GMR.
 *
 *     The guest driver should write SVGA_REG_GMR_ID first, then
 *     SVGA_REG_GMR_DESCRIPTOR.
 *
 *   SVGA_REG_GMR_MAX_IDS --
 *
 *     Read-only.
 *     The SVGA device may choose to support a maximum number of
 *     user-defined GMR IDs. This register holds the number of supported
 *     IDs. (The maximum supported ID plus 1)
 *
 *   SVGA_REG_GMR_MAX_DESCRIPTOR_LENGTH --
 *
 *     Read-only.
 *     The SVGA device may choose to put a limit on the total number
 *     of SVGAGuestMemDescriptor structures it will read when defining
 *     a single GMR.
 *
 * The descriptor structure is an array of SVGAGuestMemDescriptor
 * structures. Each structure may do one of three things:
 *
 *   - Terminate the GMR descriptor list.
 *     (ppn==0, numPages==0)
 *
 *   - Add a PPN or range of PPNs to the GMR's virtual address space.
 *     (ppn != 0, numPages != 0)
 *
 *   - Provide the PPN of the next SVGAGuestMemDescriptor, in order to
 *     support multi-page GMR descriptor tables without forcing the
 *     driver to allocate physically contiguous memory.
 *     (ppn != 0, numPages == 0)
 *
 * Note that each physical page of SVGAGuestMemDescriptor structures
 * can describe at least 2MB of guest memory. If the driver needs to
 * use more than one page of descriptor structures, it must use one of
 * its SVGAGuestMemDescriptors to point to an additional page.  The
 * device will never automatically cross a page boundary.
 *
 * Once the driver has described a GMR, it is immediately available
 * for use via any FIFO command that uses an SVGAGuestPtr structure.
 * These pointers include a GMR identifier plus an offset into that
 * GMR.
 *
 * The driver must check the SVGA_CAP_GMR bit before using the GMR
 * registers.
 */

/*
 * Special GMR IDs, allowing SVGAGuestPtrs to point to framebuffer
 * memory as well.  In the future, these IDs could even be used to
 * allow legacy memory regions to be redefined by the guest as GMRs.
 *
 * Using the guest framebuffer (GFB) at BAR1 for general purpose DMA
 * is being phased out. Please try to use user-defined GMRs whenever
 * possible.
 */
#define SVGA_GMR_NULL         ((uint32_t) -1)
#define SVGA_GMR_FRAMEBUFFER  ((uint32_t) -2)  // Guest Framebuffer (GFB)

typedef
struct SVGAGuestMemDescriptor {
   uint32_t ppn;
   uint32_t numPages;
} SVGAGuestMemDescriptor;

typedef
struct SVGAGuestPtr {
   uint32_t gmrId;
   uint32_t offset;
} SVGAGuestPtr;


/*
 * SVGAGMRImageFormat --
 *
 *    This is a packed representation of the source 2D image format
 *    for a GMR-to-screen blit. Currently it is defined as an encoding
 *    of the screen's color depth and bits-per-pixel, however, 16 bits
 *    are reserved for future use to identify other encodings (such as
 *    RGBA or higher-precision images).
 *
 *    Currently supported formats:
 *
 *       bpp depth  Format Name
 *       --- -----  -----------
 *        32    24  32-bit BGRX
 *        24    24  24-bit BGR
 *        16    16  RGB 5-6-5
 *        16    15  RGB 5-5-5
 *
 */

typedef
struct SVGAGMRImageFormat {
   union {
      struct {
         uint32_t bitsPerPixel : 8;
         uint32_t colorDepth   : 8;
         uint32_t reserved     : 16;  // Must be zero
      } s;

      uint32_t value;
   };
} SVGAGMRImageFormat;

typedef
struct SVGAGuestImage {
   SVGAGuestPtr         ptr;

   /*
    * A note on interpretation of pitch: This value of pitch is the
    * number of bytes between vertically adjacent image
    * blocks. Normally this is the number of bytes between the first
    * pixel of two adjacent scanlines. With compressed textures,
    * however, this may represent the number of bytes between
    * compression blocks rather than between rows of pixels.
    *
    * XXX: Compressed textures currently must be tightly packed in guest memory.
    *
    * If the image is 1-dimensional, pitch is ignored.
    *
    * If 'pitch' is zero, the SVGA3D device calculates a pitch value
    * assuming each row of blocks is tightly packed.
    */
   uint32_t pitch;
} SVGAGuestImage;

/*
 * SVGAColorBGRX --
 *
 *    A 24-bit color format (BGRX), which does not depend on the
 *    format of the legacy guest framebuffer (GFB) or the current
 *    GMRFB state.
 */

typedef
struct SVGAColorBGRX {
   union {
      struct {
         uint32_t b : 8;
         uint32_t g : 8;
         uint32_t r : 8;
         uint32_t x : 8;  // Unused
      } s;

      uint32_t value;
   };
} SVGAColorBGRX;


/*
 * SVGASignedRect --
 * SVGASignedPoint --
 *
 *    Signed rectangle and point primitives. These are used by the new
 *    2D primitives for drawing to Screen Objects, which can occupy a
 *    signed virtual coordinate space.
 *
 *    SVGASignedRect specifies a half-open interval: the (left, top)
 *    pixel is part of the rectangle, but the (right, bottom) pixel is
 *    not.
 */

typedef
struct SVGASignedRect {
   int32_t  left;
   int32_t  top;
   int32_t  right;
   int32_t  bottom;
} SVGASignedRect;

typedef
struct SVGASignedPoint {
   int32_t  x;
   int32_t  y;
} SVGASignedPoint;


/*
 *  Capabilities
 *
 *  Note the holes in the bitfield. Missing bits have been deprecated,
 *  and must not be reused. Those capabilities will never be reported
 *  by new versions of the SVGA device.
 *
 * SVGA_CAP_GMR2 --
 *    Provides asynchronous commands to define and remap guest memory
 *    regions.  Adds device registers SVGA_REG_GMRS_MAX_PAGES and
 *    SVGA_REG_MEMORY_SIZE.
 *
 * SVGA_CAP_SCREEN_OBJECT_2 --
 *    Allow screen object support, and require backing stores from the
 *    guest for each screen object.
 */

#define SVGA_CAP_NONE               0x00000000
#define SVGA_CAP_RECT_COPY          0x00000002
#define SVGA_CAP_CURSOR             0x00000020
#define SVGA_CAP_CURSOR_BYPASS      0x00000040   // Legacy (Use Cursor Bypass 3 instead)
#define SVGA_CAP_CURSOR_BYPASS_2    0x00000080   // Legacy (Use Cursor Bypass 3 instead)
#define SVGA_CAP_8BIT_EMULATION     0x00000100
#define SVGA_CAP_ALPHA_CURSOR       0x00000200
#define SVGA_CAP_3D                 0x00004000
#define SVGA_CAP_EXTENDED_FIFO      0x00008000
#define SVGA_CAP_MULTIMON           0x00010000   // Legacy multi-monitor support
#define SVGA_CAP_PITCHLOCK          0x00020000
#define SVGA_CAP_IRQMASK            0x00040000
#define SVGA_CAP_DISPLAY_TOPOLOGY   0x00080000   // Legacy multi-monitor support
#define SVGA_CAP_GMR                0x00100000
#define SVGA_CAP_TRACES             0x00200000
#define SVGA_CAP_GMR2               0x00400000
#define SVGA_CAP_SCREEN_OBJECT_2    0x00800000


/*
 * FIFO register indices.
 *
 * The FIFO is a chunk of device memory mapped into guest physmem.  It
 * is always treated as 32-bit words.
 *
 * The guest driver gets to decide how to partition it between
 * - FIFO registers (there are always at least 4, specifying where the
 *   following data area is and how much data it contains; there may be
 *   more registers following these, depending on the FIFO protocol
 *   version in use)
 * - FIFO data, written by the guest and slurped out by the VMX.
 * These indices are 32-bit word offsets into the FIFO.
 */

enum {
   /*
    * Block 1 (basic registers): The originally defined FIFO registers.
    * These exist and are valid for all versions of the FIFO protocol.
    */

   SVGA_FIFO_MIN = 0,
   SVGA_FIFO_MAX,       /* The distance from MIN to MAX must be at least 10K */
   SVGA_FIFO_NEXT_CMD,
   SVGA_FIFO_STOP,

   /*
    * Block 2 (extended registers): Mandatory registers for the extended
    * FIFO.  These exist if the SVGA caps register includes
    * SVGA_CAP_EXTENDED_FIFO; some of them are valid only if their
    * associated capability bit is enabled.
    *
    * Note that when originally defined, SVGA_CAP_EXTENDED_FIFO implied
    * support only for (FIFO registers) CAPABILITIES, FLAGS, and FENCE.
    * This means that the guest has to test individually (in most cases
    * using FIFO caps) for the presence of registers after this; the VMX
    * can define "extended FIFO" to mean whatever it wants, and currently
    * won't enable it unless there's room for that set and much more.
    */

   SVGA_FIFO_CAPABILITIES = 4,
   SVGA_FIFO_FLAGS,
   // Valid with SVGA_FIFO_CAP_FENCE:
   SVGA_FIFO_FENCE,

   /*
    * Block 3a (optional extended registers): Additional registers for the
    * extended FIFO, whose presence isn't actually implied by
    * SVGA_CAP_EXTENDED_FIFO; these exist if SVGA_FIFO_MIN is high enough to
    * leave room for them.
    *
    * These in block 3a, the VMX currently considers mandatory for the
    * extended FIFO.
    */

   // Valid if exists (i.e. if extended FIFO enabled):
   SVGA_FIFO_3D_HWVERSION,       /* See SVGA3dHardwareVersion in svga3d_reg.h */
   // Valid with SVGA_FIFO_CAP_PITCHLOCK:
   SVGA_FIFO_PITCHLOCK,

   // Valid with SVGA_FIFO_CAP_CURSOR_BYPASS_3:
   SVGA_FIFO_CURSOR_ON,          /* Cursor bypass 3 show/hide register */
   SVGA_FIFO_CURSOR_X,           /* Cursor bypass 3 x register */
   SVGA_FIFO_CURSOR_Y,           /* Cursor bypass 3 y register */
   SVGA_FIFO_CURSOR_COUNT,       /* Incremented when any of the other 3 change */
   SVGA_FIFO_CURSOR_LAST_UPDATED,/* Last time the host updated the cursor */

   // Valid with SVGA_FIFO_CAP_RESERVE:
   SVGA_FIFO_RESERVED,           /* Bytes past NEXT_CMD with real contents */

   /*
    * Valid with SVGA_FIFO_CAP_SCREEN_OBJECT or SVGA_FIFO_CAP_SCREEN_OBJECT_2:
    *
    * By default this is SVGA_ID_INVALID, to indicate that the cursor
    * coordinates are specified relative to the virtual root. If this
    * is set to a specific screen ID, cursor position is reinterpreted
    * as a signed offset relative to that screen's origin.
    */
   SVGA_FIFO_CURSOR_SCREEN_ID,

   /*
    * Valid with SVGA_FIFO_CAP_DEAD
    *
    * An arbitrary value written by the host, drivers should not use it.
    */
   SVGA_FIFO_DEAD,

   /*
    * Valid with SVGA_FIFO_CAP_3D_HWVERSION_REVISED:
    *
    * Contains 3D HWVERSION (see SVGA3dHardwareVersion in svga3d_reg.h)
    * on platforms that can enforce graphics resource limits.
    */
   SVGA_FIFO_3D_HWVERSION_REVISED,

   /*
    * XXX: The gap here, up until SVGA_FIFO_3D_CAPS, can be used for new
    * registers, but this must be done carefully and with judicious use of
    * capability bits, since comparisons based on SVGA_FIFO_MIN aren't
    * enough to tell you whether the register exists: we've shipped drivers
    * and products that used SVGA_FIFO_3D_CAPS but didn't know about some of
    * the earlier ones.  The actual order of introduction was:
    * - PITCHLOCK
    * - 3D_CAPS
    * - CURSOR_* (cursor bypass 3)
    * - RESERVED
    * So, code that wants to know whether it can use any of the
    * aforementioned registers, or anything else added after PITCHLOCK and
    * before 3D_CAPS, needs to reason about something other than
    * SVGA_FIFO_MIN.
    */

   /*
    * 3D caps block space; valid with 3D hardware version >=
    * SVGA3D_HWVERSION_WS6_B1.
    */
   SVGA_FIFO_3D_CAPS      = 32,
   SVGA_FIFO_3D_CAPS_LAST = 32 + 255,

   /*
    * End of VMX's current definition of "extended-FIFO registers".
    * Registers before here are always enabled/disabled as a block; either
    * the extended FIFO is enabled and includes all preceding registers, or
    * it's disabled entirely.
    *
    * Block 3b (truly optional extended registers): Additional registers for
    * the extended FIFO, which the VMX already knows how to enable and
    * disable with correct granularity.
    *
    * Registers after here exist if and only if the guest SVGA driver
    * sets SVGA_FIFO_MIN high enough to leave room for them.
    */

   // Valid if register exists:
   SVGA_FIFO_GUEST_3D_HWVERSION, /* Guest driver's 3D version */
   SVGA_FIFO_FENCE_GOAL,         /* Matching target for SVGA_IRQFLAG_FENCE_GOAL */
   SVGA_FIFO_BUSY,               /* See "FIFO Synchronization Registers" */

   /*
    * Always keep this last.  This defines the maximum number of
    * registers we know about.  At power-on, this value is placed in
    * the SVGA_REG_MEM_REGS register, and we expect the guest driver
    * to allocate this much space in FIFO memory for registers.
    */
    SVGA_FIFO_NUM_REGS
};


/*
 * Definition of registers included in extended FIFO support.
 *
 * The guest SVGA driver gets to allocate the FIFO between registers
 * and data.  It must always allocate at least 4 registers, but old
 * drivers stopped there.
 *
 * The VMX will enable extended FIFO support if and only if the guest
 * left enough room for all registers defined as part of the mandatory
 * set for the extended FIFO.
 *
 * Note that the guest drivers typically allocate the FIFO only at
 * initialization time, not at mode switches, so it's likely that the
 * number of FIFO registers won't change without a reboot.
 *
 * All registers less than this value are guaranteed to be present if
 * svgaUser->fifo.extended is set. Any later registers must be tested
 * individually for compatibility at each use (in the VMX).
 *
 * This value is used only by the VMX, so it can change without
 * affecting driver compatibility; keep it that way?
 */
#define SVGA_FIFO_EXTENDED_MANDATORY_REGS  (SVGA_FIFO_3D_CAPS_LAST + 1)


/*
 * FIFO Synchronization Registers
 *
 *  This explains the relationship between the various FIFO
 *  sync-related registers in IOSpace and in FIFO space.
 *
 *  SVGA_REG_SYNC --
 *
 *       The SYNC register can be used in two different ways by the guest:
 *
 *         1. If the guest wishes to fully sync (drain) the FIFO,
 *            it will write once to SYNC then poll on the BUSY
 *            register. The FIFO is sync'ed once BUSY is zero.
 *
 *         2. If the guest wants to asynchronously wake up the host,
 *            it will write once to SYNC without polling on BUSY.
 *            Ideally it will do this after some new commands have
 *            been placed in the FIFO, and after reading a zero
 *            from SVGA_FIFO_BUSY.
 *
 *       (1) is the original behaviour that SYNC was designed to
 *       support.  Originally, a write to SYNC would implicitly
 *       trigger a read from BUSY. This causes us to synchronously
 *       process the FIFO.
 *
 *       This behaviour has since been changed so that writing SYNC
 *       will *not* implicitly cause a read from BUSY. Instead, it
 *       makes a channel call which asynchronously wakes up the MKS
 *       thread.
 *
 *       New guests can use this new behaviour to implement (2)
 *       efficiently. This lets guests get the host's attention
 *       without waiting for the MKS to poll, which gives us much
 *       better CPU utilization on SMP hosts and on UP hosts while
 *       we're blocked on the host GPU.
 *
 *       Old guests shouldn't notice the behaviour change. SYNC was
 *       never guaranteed to process the entire FIFO, since it was
 *       bounded to a particular number of CPU cycles. Old guests will
 *       still loop on the BUSY register until the FIFO is empty.
 *
 *       Writing to SYNC currently has the following side-effects:
 *
 *         - Sets SVGA_REG_BUSY to TRUE (in the monitor)
 *         - Asynchronously wakes up the MKS thread for FIFO processing
 *         - The value written to SYNC is recorded as a "reason", for
 *           stats purposes.
 *
 *       If SVGA_FIFO_BUSY is available, drivers are advised to only
 *       write to SYNC if SVGA_FIFO_BUSY is FALSE. Drivers should set
 *       SVGA_FIFO_BUSY to TRUE after writing to SYNC. The MKS will
 *       eventually set SVGA_FIFO_BUSY on its own, but this approach
 *       lets the driver avoid sending multiple asynchronous wakeup
 *       messages to the MKS thread.
 *
 *  SVGA_REG_BUSY --
 *
 *       This register is set to TRUE when SVGA_REG_SYNC is written,
 *       and it reads as FALSE when the FIFO has been completely
 *       drained.
 *
 *       Every read from this register causes us to synchronously
 *       process FIFO commands. There is no guarantee as to how many
 *       commands each read will process.
 *
 *       CPU time spent processing FIFO commands will be billed to
 *       the guest.
 *
 *       New drivers should avoid using this register unless they
 *       need to guarantee that the FIFO is completely drained. It
 *       is overkill for performing a sync-to-fence. Older drivers
 *       will use this register for any type of synchronization.
 *
 *  SVGA_FIFO_BUSY --
 *
 *       This register is a fast way for the guest driver to check
 *       whether the FIFO is already being processed. It reads and
 *       writes at normal RAM speeds, with no monitor intervention.
 *
 *       If this register reads as TRUE, the host is guaranteeing that
 *       any new commands written into the FIFO will be noticed before
 *       the MKS goes back to sleep.
 *
 *       If this register reads as FALSE, no such guarantee can be
 *       made.
 *
 *       The guest should use this register to quickly determine
 *       whether or not it needs to wake up the host. If the guest
 *       just wrote a command or group of commands that it would like
 *       the host to begin processing, it should:
 *
 *         1. Read SVGA_FIFO_BUSY. If it reads as TRUE, no further
 *            action is necessary.
 *
 *         2. Write TRUE to SVGA_FIFO_BUSY. This informs future guest
 *            code that we've already sent a SYNC to the host and we
 *            don't need to send a duplicate.
 *
 *         3. Write a reason to SVGA_REG_SYNC. This will send an
 *            asynchronous wakeup to the MKS thread.
 */


/*
 * FIFO Capabilities
 *
 *      Fence -- Fence register and command are supported
 *      Accel Front -- Front buffer only commands are supported
 *      Pitch Lock -- Pitch lock register is supported
 *      Video -- SVGA Video overlay units are supported
 *      Escape -- Escape command is supported
 *
 * XXX: Add longer descriptions for each capability, including a list
 *      of the new features that each capability provides.
 *
 * SVGA_FIFO_CAP_SCREEN_OBJECT --
 *
 *    Provides dynamic multi-screen rendering, for improved Unity and
 *    multi-monitor modes. With Screen Object, the guest can
 *    dynamically create and destroy 'screens', which can represent
 *    Unity windows or virtual monitors. Screen Object also provides
 *    strong guarantees that DMA operations happen only when
 *    guest-initiated. Screen Object deprecates the BAR1 guest
 *    framebuffer (GFB) and all commands that work only with the GFB.
 *
 *    New registers:
 *       FIFO_CURSOR_SCREEN_ID, VIDEO_DATA_GMRID, VIDEO_DST_SCREEN_ID
 *
 *    New 2D commands:
 *       DEFINE_SCREEN, DESTROY_SCREEN, DEFINE_GMRFB, BLIT_GMRFB_TO_SCREEN,
 *       BLIT_SCREEN_TO_GMRFB, ANNOTATION_FILL, ANNOTATION_COPY
 *
 *    New 3D commands:
 *       BLIT_SURFACE_TO_SCREEN
 *
 *    New guarantees:
 *
 *       - The host will not read or write guest memory, including the GFB,
 *         except when explicitly initiated by a DMA command.
 *
 *       - All DMA, including legacy DMA like UPDATE and PRESENT_READBACK,
 *         is guaranteed to complete before any subsequent FENCEs.
 *
 *       - All legacy commands which affect a Screen (UPDATE, PRESENT,
 *         PRESENT_READBACK) as well as new Screen blit commands will
 *         all behave consistently as blits, and memory will be read
 *         or written in FIFO order.
 *
 *         For example, if you PRESENT from one SVGA3D surface to multiple
 *         places on the screen, the data copied will always be from the
 *         SVGA3D surface at the time the PRESENT was issued in the FIFO.
 *         This was not necessarily true on devices without Screen Object.
 *
 *         This means that on devices that support Screen Object, the
 *         PRESENT_READBACK command should not be necessary unless you
 *         actually want to read back the results of 3D rendering into
 *         system memory. (And for that, the BLIT_SCREEN_TO_GMRFB
 *         command provides a strict superset of functionality.)
 *
 *       - When a screen is resized, either using Screen Object commands or
 *         legacy multimon registers, its contents are preserved.
 *
 * SVGA_FIFO_CAP_GMR2 --
 *
 *    Provides new commands to define and remap guest memory regions (GMR).
 *
 *    New 2D commands:
 *       DEFINE_GMR2, REMAP_GMR2.
 *
 * SVGA_FIFO_CAP_3D_HWVERSION_REVISED --
 *
 *    Indicates new register SVGA_FIFO_3D_HWVERSION_REVISED exists.
 *    This register may replace SVGA_FIFO_3D_HWVERSION on platforms
 *    that enforce graphics resource limits.  This allows the platform
 *    to clear SVGA_FIFO_3D_HWVERSION and disable 3D in legacy guest
 *    drivers that do not limit their resources.
 *
 *    Note this is an alias to SVGA_FIFO_CAP_GMR2 because these indicators
 *    are codependent (and thus we use a single capability bit).
 *
 * SVGA_FIFO_CAP_SCREEN_OBJECT_2 --
 *
 *    Modifies the DEFINE_SCREEN command to include a guest provided
 *    backing store in GMR memory and the bytesPerLine for the backing
 *    store.  This capability requires the use of a backing store when
 *    creating screen objects.  However if SVGA_FIFO_CAP_SCREEN_OBJECT
 *    is present then backing stores are optional.
 *
 * SVGA_FIFO_CAP_DEAD --
 *
 *    Drivers should not use this cap bit.  This cap bit can not be
 *    reused since some hosts already expose it.
 */

#define SVGA_FIFO_CAP_NONE                  0
#define SVGA_FIFO_CAP_FENCE             (1<<0)
#define SVGA_FIFO_CAP_ACCELFRONT        (1<<1)
#define SVGA_FIFO_CAP_PITCHLOCK         (1<<2)
#define SVGA_FIFO_CAP_VIDEO             (1<<3)
#define SVGA_FIFO_CAP_CURSOR_BYPASS_3   (1<<4)
#define SVGA_FIFO_CAP_ESCAPE            (1<<5)
#define SVGA_FIFO_CAP_RESERVE           (1<<6)
#define SVGA_FIFO_CAP_SCREEN_OBJECT     (1<<7)
#define SVGA_FIFO_CAP_GMR2              (1<<8)
#define SVGA_FIFO_CAP_3D_HWVERSION_REVISED  SVGA_FIFO_CAP_GMR2
#define SVGA_FIFO_CAP_SCREEN_OBJECT_2   (1<<9)
#define SVGA_FIFO_CAP_DEAD              (1<<10)


/*
 * FIFO Flags
 *
 *      Accel Front -- Driver should use front buffer only commands
 */

#define SVGA_FIFO_FLAG_NONE                 0
#define SVGA_FIFO_FLAG_ACCELFRONT       (1<<0)
#define SVGA_FIFO_FLAG_RESERVED        (1<<31) // Internal use only

/*
 * FIFO reservation sentinel value
 */

#define SVGA_FIFO_RESERVED_UNKNOWN      0xffffffff


/*
 * Video overlay support
 */

#define SVGA_NUM_OVERLAY_UNITS 32


/*
 * Video capabilities that the guest is currently using
 */

#define SVGA_VIDEO_FLAG_COLORKEY        0x0001


/*
 * Offsets for the video overlay registers
 */

enum {
   SVGA_VIDEO_ENABLED = 0,
   SVGA_VIDEO_FLAGS,
   SVGA_VIDEO_DATA_OFFSET,
   SVGA_VIDEO_FORMAT,
   SVGA_VIDEO_COLORKEY,
   SVGA_VIDEO_SIZE,          // Deprecated
   SVGA_VIDEO_WIDTH,
   SVGA_VIDEO_HEIGHT,
   SVGA_VIDEO_SRC_X,
   SVGA_VIDEO_SRC_Y,
   SVGA_VIDEO_SRC_WIDTH,
   SVGA_VIDEO_SRC_HEIGHT,
   SVGA_VIDEO_DST_X,         // Signed int32
   SVGA_VIDEO_DST_Y,         // Signed int32
   SVGA_VIDEO_DST_WIDTH,
   SVGA_VIDEO_DST_HEIGHT,
   SVGA_VIDEO_PITCH_1,
   SVGA_VIDEO_PITCH_2,
   SVGA_VIDEO_PITCH_3,
   SVGA_VIDEO_DATA_GMRID,    // Optional, defaults to SVGA_GMR_FRAMEBUFFER
   SVGA_VIDEO_DST_SCREEN_ID, // Optional, defaults to virtual coords (SVGA_ID_INVALID)
   SVGA_VIDEO_NUM_REGS
};


/*
 * SVGA Overlay Units
 *
 *      width and height relate to the entire source video frame.
 *      srcX, srcY, srcWidth and srcHeight represent subset of the source
 *      video frame to be displayed.
 */

typedef struct SVGAOverlayUnit {
   uint32_t enabled;
   uint32_t flags;
   uint32_t dataOffset;
   uint32_t format;
   uint32_t colorKey;
   uint32_t size;
   uint32_t width;
   uint32_t height;
   uint32_t srcX;
   uint32_t srcY;
   uint32_t srcWidth;
   uint32_t srcHeight;
   int32_t  dstX;
   int32_t  dstY;
   uint32_t dstWidth;
   uint32_t dstHeight;
   uint32_t pitches[3];
   uint32_t dataGMRId;
   uint32_t dstScreenId;
} SVGAOverlayUnit;


/*
 * SVGAScreenObject --
 *
 *    This is a new way to represent a guest's multi-monitor screen or
 *    Unity window. Screen objects are only supported if the
 *    SVGA_FIFO_CAP_SCREEN_OBJECT capability bit is set.
 *
 *    If Screen Objects are supported, they can be used to fully
 *    replace the functionality provided by the framebuffer registers
 *    (SVGA_REG_WIDTH, HEIGHT, etc.) and by SVGA_CAP_DISPLAY_TOPOLOGY.
 *
 *    The screen object is a struct with guaranteed binary
 *    compatibility. New flags can be added, and the struct may grow,
 *    but existing fields must retain their meaning.
 *
 *    Added with SVGA_FIFO_CAP_SCREEN_OBJECT_2 are required fields of
 *    a SVGAGuestPtr that is used to back the screen contents.  This
 *    memory must come from the GFB.  The guest is not allowed to
 *    access the memory and doing so will have undefined results.  The
 *    backing store is required to be page aligned and the size is
 *    padded to the next page boundry.  The number of pages is:
 *       (bytesPerLine * size.width * 4 + PAGE_SIZE - 1) / PAGE_SIZE
 *
 *    The pitch in the backingStore is required to be at least large
 *    enough to hold a 32bbp scanline.  It is recommended that the
 *    driver pad bytesPerLine for a potential performance win.
 *
 *    The cloneCount field is treated as a hint from the guest that
 *    the user wants this display to be cloned, countCount times.  A
 *    value of zero means no cloning should happen.
 */

#define SVGA_SCREEN_MUST_BE_SET     (1 << 0) // Must be set or results undefined
#define SVGA_SCREEN_HAS_ROOT SVGA_SCREEN_MUST_BE_SET // Deprecated
#define SVGA_SCREEN_IS_PRIMARY      (1 << 1) // Guest considers this screen to be 'primary'
#define SVGA_SCREEN_FULLSCREEN_HINT (1 << 2)  // Guest is running a fullscreen app here

/*
 * Added with SVGA_FIFO_CAP_SCREEN_OBJECT_2.  When the screen is
 * deactivated the base layer is defined to lose all contents and
 * become black.  When a screen is deactivated the backing store is
 * optional.  When set backingPtr and bytesPerLine will be ignored.
 */
#define SVGA_SCREEN_DEACTIVATE  (1 << 3)

/*
 * Added with SVGA_FIFO_CAP_SCREEN_OBJECT_2.  When this flag is set
 * the screen contents will be outputted as all black to the user
 * though the base layer contents is preserved.  The screen base layer
 * can still be read and written to like normal though the no visible
 * effect will be seen by the user.  When the flag is changed the
 * screen will be blanked or redrawn to the current contents as needed
 * without any extra commands from the driver.  This flag only has an
 * effect when the screen is not deactivated.
 */
#define SVGA_SCREEN_BLANKING (1 << 4)

typedef
struct SVGAScreenObject {
   uint32_t structSize;   // sizeof(SVGAScreenObject)
   uint32_t id;
   uint32_t flags;
   struct {
      uint32_t width;
      uint32_t height;
   } size;
   struct {
      int32_t x;
      int32_t y;
   } root;

   /*
    * Added and required by SVGA_FIFO_CAP_SCREEN_OBJECT_2, optional
    * with SVGA_FIFO_CAP_SCREEN_OBJECT.
    */
   SVGAGuestImage backingStore;
   uint32_t cloneCount;
} SVGAScreenObject;


/*
 *  Commands in the command FIFO:
 *
 *  Command IDs defined below are used for the traditional 2D FIFO
 *  communication (not all commands are available for all versions of the
 *  SVGA FIFO protocol).
 *
 *  Note the holes in the command ID numbers: These commands have been
 *  deprecated, and the old IDs must not be reused.
 *
 *  Command IDs from 1000 to 1999 are reserved for use by the SVGA3D
 *  protocol.
 *
 *  Each command's parameters are described by the comments and
 *  structs below.
 */

typedef enum {
   SVGA_CMD_INVALID_CMD           = 0,
   SVGA_CMD_UPDATE                = 1,
   SVGA_CMD_RECT_COPY             = 3,
   SVGA_CMD_DEFINE_CURSOR         = 19,
   SVGA_CMD_DEFINE_ALPHA_CURSOR   = 22,
   SVGA_CMD_UPDATE_VERBOSE        = 25,
   SVGA_CMD_FRONT_ROP_FILL        = 29,
   SVGA_CMD_FENCE                 = 30,
   SVGA_CMD_ESCAPE                = 33,
   SVGA_CMD_DEFINE_SCREEN         = 34,
   SVGA_CMD_DESTROY_SCREEN        = 35,
   SVGA_CMD_DEFINE_GMRFB          = 36,
   SVGA_CMD_BLIT_GMRFB_TO_SCREEN  = 37,
   SVGA_CMD_BLIT_SCREEN_TO_GMRFB  = 38,
   SVGA_CMD_ANNOTATION_FILL       = 39,
   SVGA_CMD_ANNOTATION_COPY       = 40,
   SVGA_CMD_DEFINE_GMR2           = 41,
   SVGA_CMD_REMAP_GMR2            = 42,
   SVGA_CMD_MAX
} SVGAFifoCmdId;

#define SVGA_CMD_MAX_DATASIZE       (256 * 1024)
#define SVGA_CMD_MAX_ARGS           64


/*
 * SVGA_CMD_UPDATE --
 *
 *    This is a DMA transfer which copies from the Guest Framebuffer
 *    (GFB) at BAR1 + SVGA_REG_FB_OFFSET to any screens which
 *    intersect with the provided virtual rectangle.
 *
 *    This command does not support using arbitrary guest memory as a
 *    data source- it only works with the pre-defined GFB memory.
 *    This command also does not support signed virtual coordinates.
 *    If you have defined screens (using SVGA_CMD_DEFINE_SCREEN) with
 *    negative root x/y coordinates, the negative portion of those
 *    screens will not be reachable by this command.
 *
 *    This command is not necessary when using framebuffer
 *    traces. Traces are automatically enabled if the SVGA FIFO is
 *    disabled, and you may explicitly enable/disable traces using
 *    SVGA_REG_TRACES. With traces enabled, any write to the GFB will
 *    automatically act as if a subsequent SVGA_CMD_UPDATE was issued.
 *
 *    Traces and SVGA_CMD_UPDATE are the only supported ways to render
 *    pseudocolor screen updates. The newer Screen Object commands
 *    only support true color formats.
 *
 * Availability:
 *    Always available.
 */

typedef
struct {
   uint32_t x;
   uint32_t y;
   uint32_t width;
   uint32_t height;
} SVGAFifoCmdUpdate;


/*
 * SVGA_CMD_RECT_COPY --
 *
 *    Perform a rectangular DMA transfer from one area of the GFB to
 *    another, and copy the result to any screens which intersect it.
 *
 * Availability:
 *    SVGA_CAP_RECT_COPY
 */

typedef
struct {
   uint32_t srcX;
   uint32_t srcY;
   uint32_t destX;
   uint32_t destY;
   uint32_t width;
   uint32_t height;
} SVGAFifoCmdRectCopy;


/*
 * SVGA_CMD_DEFINE_CURSOR --
 *
 *    Provide a new cursor image, as an AND/XOR mask.
 *
 *    The recommended way to position the cursor overlay is by using
 *    the SVGA_FIFO_CURSOR_* registers, supported by the
 *    SVGA_FIFO_CAP_CURSOR_BYPASS_3 capability.
 *
 * Availability:
 *    SVGA_CAP_CURSOR
 */

typedef
struct {
   uint32_t id;             // Reserved, must be zero.
   uint32_t hotspotX;
   uint32_t hotspotY;
   uint32_t width;
   uint32_t height;
   uint32_t andMaskDepth;   // Value must be 1 or equal to BITS_PER_PIXEL
   uint32_t xorMaskDepth;   // Value must be 1 or equal to BITS_PER_PIXEL
   /*
    * Followed by scanline data for AND mask, then XOR mask.
    * Each scanline is padded to a 32-bit boundary.
   */
} SVGAFifoCmdDefineCursor;


/*
 * SVGA_CMD_DEFINE_ALPHA_CURSOR --
 *
 *    Provide a new cursor image, in 32-bit BGRA format.
 *
 *    The recommended way to position the cursor overlay is by using
 *    the SVGA_FIFO_CURSOR_* registers, supported by the
 *    SVGA_FIFO_CAP_CURSOR_BYPASS_3 capability.
 *
 * Availability:
 *    SVGA_CAP_ALPHA_CURSOR
 */

typedef
struct {
   uint32_t id;             // Reserved, must be zero.
   uint32_t hotspotX;
   uint32_t hotspotY;
   uint32_t width;
   uint32_t height;
   /* Followed by scanline data */
} SVGAFifoCmdDefineAlphaCursor;


/*
 * SVGA_CMD_UPDATE_VERBOSE --
 *
 *    Just like SVGA_CMD_UPDATE, but also provide a per-rectangle
 *    'reason' value, an opaque cookie which is used by internal
 *    debugging tools. Third party drivers should not use this
 *    command.
 *
 * Availability:
 *    SVGA_CAP_EXTENDED_FIFO
 */

typedef
struct {
   uint32_t x;
   uint32_t y;
   uint32_t width;
   uint32_t height;
   uint32_t reason;
} SVGAFifoCmdUpdateVerbose;


/*
 * SVGA_CMD_FRONT_ROP_FILL --
 *
 *    This is a hint which tells the SVGA device that the driver has
 *    just filled a rectangular region of the GFB with a solid
 *    color. Instead of reading these pixels from the GFB, the device
 *    can assume that they all equal 'color'. This is primarily used
 *    for remote desktop protocols.
 *
 * Availability:
 *    SVGA_FIFO_CAP_ACCELFRONT
 */

#define  SVGA_ROP_COPY                    0x03

typedef
struct {
   uint32_t color;     // In the same format as the GFB
   uint32_t x;
   uint32_t y;
   uint32_t width;
   uint32_t height;
   uint32_t rop;       // Must be SVGA_ROP_COPY
} SVGAFifoCmdFrontRopFill;


/*
 * SVGA_CMD_FENCE --
 *
 *    Insert a synchronization fence.  When the SVGA device reaches
 *    this command, it will copy the 'fence' value into the
 *    SVGA_FIFO_FENCE register. It will also compare the fence against
 *    SVGA_FIFO_FENCE_GOAL. If the fence matches the goal and the
 *    SVGA_IRQFLAG_FENCE_GOAL interrupt is enabled, the device will
 *    raise this interrupt.
 *
 * Availability:
 *    SVGA_FIFO_FENCE for this command,
 *    SVGA_CAP_IRQMASK for SVGA_FIFO_FENCE_GOAL.
 */

typedef
struct {
   uint32_t fence;
} SVGAFifoCmdFence;


/*
 * SVGA_CMD_ESCAPE --
 *
 *    Send an extended or vendor-specific variable length command.
 *    This is used for video overlay, third party plugins, and
 *    internal debugging tools. See svga_escape.h
 *
 * Availability:
 *    SVGA_FIFO_CAP_ESCAPE
 */

typedef
struct {
   uint32_t nsid;
   uint32_t size;
   /* followed by 'size' bytes of data */
} SVGAFifoCmdEscape;


/*
 * SVGA_CMD_DEFINE_SCREEN --
 *
 *    Define or redefine an SVGAScreenObject. See the description of
 *    SVGAScreenObject above.  The video driver is responsible for
 *    generating new screen IDs. They should be small positive
 *    integers. The virtual device will have an implementation
 *    specific upper limit on the number of screen IDs
 *    supported. Drivers are responsible for recycling IDs. The first
 *    valid ID is zero.
 *
 *    - Interaction with other registers:
 *
 *    For backwards compatibility, when the GFB mode registers (WIDTH,
 *    HEIGHT, PITCHLOCK, BITS_PER_PIXEL) are modified, the SVGA device
 *    deletes all screens other than screen #0, and redefines screen
 *    #0 according to the specified mode. Drivers that use
 *    SVGA_CMD_DEFINE_SCREEN should destroy or redefine screen #0.
 *
 *    If you use screen objects, do not use the legacy multi-mon
 *    registers (SVGA_REG_NUM_GUEST_DISPLAYS, SVGA_REG_DISPLAY_*).
 *
 * Availability:
 *    SVGA_FIFO_CAP_SCREEN_OBJECT or SVGA_FIFO_CAP_SCREEN_OBJECT_2
 */

typedef
struct {
   SVGAScreenObject screen;   // Variable-length according to version
} SVGAFifoCmdDefineScreen;


/*
 * SVGA_CMD_DESTROY_SCREEN --
 *
 *    Destroy an SVGAScreenObject. Its ID is immediately available for
 *    re-use.
 *
 * Availability:
 *    SVGA_FIFO_CAP_SCREEN_OBJECT or SVGA_FIFO_CAP_SCREEN_OBJECT_2
 */

typedef
struct {
   uint32_t screenId;
} SVGAFifoCmdDestroyScreen;


/*
 * SVGA_CMD_DEFINE_GMRFB --
 *
 *    This command sets a piece of SVGA device state called the
 *    Guest Memory Region Framebuffer, or GMRFB. The GMRFB is a
 *    piece of light-weight state which identifies the location and
 *    format of an image in guest memory or in BAR1. The GMRFB has
 *    an arbitrary size, and it doesn't need to match the geometry
 *    of the GFB or any screen object.
 *
 *    The GMRFB can be redefined as often as you like. You could
 *    always use the same GMRFB, you could redefine it before
 *    rendering from a different guest screen, or you could even
 *    redefine it before every blit.
 *
 *    There are multiple ways to use this command. The simplest way is
 *    to use it to move the framebuffer either to elsewhere in the GFB
 *    (BAR1) memory region, or to a user-defined GMR. This lets a
 *    driver use a framebuffer allocated entirely out of normal system
 *    memory, which we encourage.
 *
 *    Another way to use this command is to set up a ring buffer of
 *    updates in GFB memory. If a driver wants to ensure that no
 *    frames are skipped by the SVGA device, it is important that the
 *    driver not modify the source data for a blit until the device is
 *    done processing the command. One efficient way to accomplish
 *    this is to use a ring of small DMA buffers. Each buffer is used
 *    for one blit, then we move on to the next buffer in the
 *    ring. The FENCE mechanism is used to protect each buffer from
 *    re-use until the device is finished with that buffer's
 *    corresponding blit.
 *
 *    This command does not affect the meaning of SVGA_CMD_UPDATE.
 *    UPDATEs always occur from the legacy GFB memory area. This
 *    command has no support for pseudocolor GMRFBs. Currently only
 *    true-color 15, 16, and 24-bit depths are supported. Future
 *    devices may expose capabilities for additional framebuffer
 *    formats.
 *
 *    The default GMRFB value is undefined. Drivers must always send
 *    this command at least once before performing any blit from the
 *    GMRFB.
 *
 * Availability:
 *    SVGA_FIFO_CAP_SCREEN_OBJECT or SVGA_FIFO_CAP_SCREEN_OBJECT_2
 */

typedef
struct {
   SVGAGuestPtr        ptr;
   uint32_t              bytesPerLine;
   SVGAGMRImageFormat  format;
} SVGAFifoCmdDefineGMRFB;


/*
 * SVGA_CMD_BLIT_GMRFB_TO_SCREEN --
 *
 *    This is a guest-to-host blit. It performs a DMA operation to
 *    copy a rectangular region of pixels from the current GMRFB to
 *    one or more Screen Objects.
 *
 *    The destination coordinate may be specified relative to a
 *    screen's origin (if a screen ID is specified) or relative to the
 *    virtual coordinate system's origin (if the screen ID is
 *    SVGA_ID_INVALID). The actual destination may span zero or more
 *    screens, in the case of a virtual destination rect or a rect
 *    which extends off the edge of the specified screen.
 *
 *    This command writes to the screen's "base layer": the underlying
 *    framebuffer which exists below any cursor or video overlays. No
 *    action is necessary to explicitly hide or update any overlays
 *    which exist on top of the updated region.
 *
 *    The SVGA device is guaranteed to finish reading from the GMRFB
 *    by the time any subsequent FENCE commands are reached.
 *
 *    This command consumes an annotation. See the
 *    SVGA_CMD_ANNOTATION_* commands for details.
 *
 * Availability:
 *    SVGA_FIFO_CAP_SCREEN_OBJECT or SVGA_FIFO_CAP_SCREEN_OBJECT_2
 */

typedef
struct {
   SVGASignedPoint  srcOrigin;
   SVGASignedRect   destRect;
   uint32_t           destScreenId;
} SVGAFifoCmdBlitGMRFBToScreen;


/*
 * SVGA_CMD_BLIT_SCREEN_TO_GMRFB --
 *
 *    This is a host-to-guest blit. It performs a DMA operation to
 *    copy a rectangular region of pixels from a single Screen Object
 *    back to the current GMRFB.
 *
 *    Usage note: This command should be used rarely. It will
 *    typically be inefficient, but it is necessary for some types of
 *    synchronization between 3D (GPU) and 2D (CPU) rendering into
 *    overlapping areas of a screen.
 *
 *    The source coordinate is specified relative to a screen's
 *    origin. The provided screen ID must be valid. If any parameters
 *    are invalid, the resulting pixel values are undefined.
 *
 *    This command reads the screen's "base layer". Overlays like
 *    video and cursor are not included, but any data which was sent
 *    using a blit-to-screen primitive will be available, no matter
 *    whether the data's original source was the GMRFB or the 3D
 *    acceleration hardware.
 *
 *    Note that our guest-to-host blits and host-to-guest blits aren't
 *    symmetric in their current implementation. While the parameters
 *    are identical, host-to-guest blits are a lot less featureful.
 *    They do not support clipping: If the source parameters don't
 *    fully fit within a screen, the blit fails. They must originate
 *    from exactly one screen. Virtual coordinates are not directly
 *    supported.
 *
 *    Host-to-guest blits do support the same set of GMRFB formats
 *    offered by guest-to-host blits.
 *
 *    The SVGA device is guaranteed to finish writing to the GMRFB by
 *    the time any subsequent FENCE commands are reached.
 *
 * Availability:
 *    SVGA_FIFO_CAP_SCREEN_OBJECT or SVGA_FIFO_CAP_SCREEN_OBJECT_2
 */

typedef
struct {
   SVGASignedPoint  destOrigin;
   SVGASignedRect   srcRect;
   uint32_t           srcScreenId;
} SVGAFifoCmdBlitScreenToGMRFB;


/*
 * SVGA_CMD_ANNOTATION_FILL --
 *
 *    This is a blit annotation. This command stores a small piece of
 *    device state which is consumed by the next blit-to-screen
 *    command. The state is only cleared by commands which are
 *    specifically documented as consuming an annotation. Other
 *    commands (such as ESCAPEs for debugging) may intervene between
 *    the annotation and its associated blit.
 *
 *    This annotation is a promise about the contents of the next
 *    blit: The video driver is guaranteeing that all pixels in that
 *    blit will have the same value, specified here as a color in
 *    SVGAColorBGRX format.
 *
 *    The SVGA device can still render the blit correctly even if it
 *    ignores this annotation, but the annotation may allow it to
 *    perform the blit more efficiently, for example by ignoring the
 *    source data and performing a fill in hardware.
 *
 *    This annotation is most important for performance when the
 *    user's display is being remoted over a network connection.
 *
 * Availability:
 *    SVGA_FIFO_CAP_SCREEN_OBJECT or SVGA_FIFO_CAP_SCREEN_OBJECT_2
 */

typedef
struct {
   SVGAColorBGRX  color;
} SVGAFifoCmdAnnotationFill;


/*
 * SVGA_CMD_ANNOTATION_COPY --
 *
 *    This is a blit annotation. See SVGA_CMD_ANNOTATION_FILL for more
 *    information about annotations.
 *
 *    This annotation is a promise about the contents of the next
 *    blit: The video driver is guaranteeing that all pixels in that
 *    blit will have the same value as those which already exist at an
 *    identically-sized region on the same or a different screen.
 *
 *    Note that the source pixels for the COPY in this annotation are
 *    sampled before applying the anqnotation's associated blit. They
 *    are allowed to overlap with the blit's destination pixels.
 *
 *    The copy source rectangle is specified the same way as the blit
 *    destination: it can be a rectangle which spans zero or more
 *    screens, specified relative to either a screen or to the virtual
 *    coordinate system's origin. If the source rectangle includes
 *    pixels which are not from exactly one screen, the results are
 *    undefined.
 *
 * Availability:
 *    SVGA_FIFO_CAP_SCREEN_OBJECT or SVGA_FIFO_CAP_SCREEN_OBJECT_2
 */

typedef
struct {
   SVGASignedPoint  srcOrigin;
   uint32_t           srcScreenId;
} SVGAFifoCmdAnnotationCopy;


/*
 * SVGA_CMD_DEFINE_GMR2 --
 *
 *    Define guest memory region v2.  See the description of GMRs above.
 *
 * Availability:
 *    SVGA_CAP_GMR2
 */

typedef
struct {
   uint32_t gmrId;
   uint32_t numPages;
}
SVGAFifoCmdDefineGMR2;


/*
 * SVGA_CMD_REMAP_GMR2 --
 *
 *    Remap guest memory region v2.  See the description of GMRs above.
 *
 *    This command allows guest to modify a portion of an existing GMR by
 *    invalidating it or reassigning it to different guest physical pages.
 *    The pages are identified by physical page number (PPN).  The pages
 *    are assumed to be pinned and valid for DMA operations.
 *
 *    Description of command flags:
 *
 *    SVGA_REMAP_GMR2_VIA_GMR: If enabled, references a PPN list in a GMR.
 *       The PPN list must not overlap with the remap region (this can be
 *       handled trivially by referencing a separate GMR).  If flag is
 *       disabled, PPN list is appended to SVGARemapGMR command.
 *
 *    SVGA_REMAP_GMR2_PPN64: If set, PPN list is in PPN64 format, otherwise
 *       it is in PPN32 format.
 *
 *    SVGA_REMAP_GMR2_SINGLE_PPN: If set, PPN list contains a single entry.
 *       A single PPN can be used to invalidate a portion of a GMR or
 *       map it to to a single guest scratch page.
 *
 * Availability:
 *    SVGA_CAP_GMR2
 */

typedef enum {
   SVGA_REMAP_GMR2_PPN32         = 0,
   SVGA_REMAP_GMR2_VIA_GMR       = (1 << 0),
   SVGA_REMAP_GMR2_PPN64         = (1 << 1),
   SVGA_REMAP_GMR2_SINGLE_PPN    = (1 << 2)
} SVGARemapGMR2Flags;

typedef
struct {
   uint32_t gmrId;
   SVGARemapGMR2Flags flags;
   uint32_t offsetPages; // offset in pages to begin remap
   uint32_t numPages; // number of pages to remap
   /*
    * Followed by additional data depending on SVGARemapGMR2Flags.
    *
    * If flag SVGA_REMAP_GMR2_VIA_GMR is set, single SVGAGuestPtr follows.
    * Otherwise an array of page descriptors in PPN32 or PPN64 format
    * (according to flag SVGA_REMAP_GMR2_PPN64) follows.  If flag
    * SVGA_REMAP_GMR2_SINGLE_PPN is set, array contains a single entry.
    */
}
SVGAFifoCmdRemapGMR2;

#endif