Intel Surface Layout (ISL)

The Intel Surface Layout library (ISL) is a subproject in Mesa for doing surface layout calculations for Intel graphics drivers. It was originally written by Chad Versace and is now maintained by Jason Ekstrand and Nanley Chery.

• Units
• Surface Formats
  • Data Encoding
  • Data Layout
  • Understanding sRGB
  • Surface Format Introspection API
  • Surface Format Enums
• Tiling
  • Basics
  • ISL Representation
  • X-tiling
  • Y-tiling
  • W-tiling
  • Tile4
  • Tiling as a bit pattern
• Auxiliary surface compression
  • Types of surface compression
  • Creating auxiliary surfaces
  • Compression state tracking
• Single-sampled Color Compression
  • CCS data
  • CCS surface layout
  • CCS on Tigerlake and above
• Hierarchical Depth (HiZ)
  • HiZ/stencil on Sandy Bridge

The core representation of a surface in ISL is isl_surf.

struct isl_surf

Public Members

enum isl_surf_dim dim

Dimensionality of the surface

enum isl_dim_layout dim_layout

Spatial layout of the surface in memory

This is dependent on isl_surf::dim and hardware generation.

enum isl_msaa_layout msaa_layout

Spatial layout of the samples if isl_surf::samples > 1

enum isl_tiling tiling

Memory tiling used by the surface

enum isl_format format

Base image format of the surface

This need not be the same as the format specified in isl_view::format when a surface state is constructed. It must, however, have the same number of bits per pixel or else memory calculations will go wrong.

struct isl_extent3d image_alignment_el

Alignment of the upper-left sample of each subimage, in units of surface elements.

struct isl_extent4d logical_level0_px

Logical extent of the surface’s base level, in units of pixels. This is identical to the extent defined in isl_surf_init_info.

struct isl_extent4d phys_level0_sa

Physical extent of the surface’s base level, in units of physical surface samples.

Consider isl_dim_layout as an operator that transforms a logical surface layout to a physical surface layout. Then

logical_layout := (isl_surf::dim, isl_surf::logical_level0_px) isl_surf::phys_level0_sa := isl_surf::dim_layout * logical_layout

uint32_t levels

Number of miplevels in the surface

uint32_t samples

Number of samples in the surface

Invariant

samples >= 1

uint64_t size_B

Total size of the surface, in bytes.

uint32_t alignment_B

Required alignment for the surface’s base address.

uint32_t row_pitch_B

The interpretation of this field depends on the value of isl_tile_info::physical_extent_B. In particular, the width of the surface in tiles is row_pitch_B / isl_tile_info::physical_extent_B.width and the distance in bytes between vertically adjacent tiles in the image is given by row_pitch_B * isl_tile_info::physical_extent_B.height.

For linear images where isl_tile_info::physical_extent_B.height == 1, this cleanly reduces to being the distance, in bytes, between vertically adjacent surface elements.

See

isl_tile_info::phys_extent_B;

uint32_t array_pitch_el_rows

Pitch between physical array slices, in rows of surface elements.

isl_surf_usage_flags_t usage

Copy of isl_surf_init_info::usage.