meson: Add "amber" option for automatic LTS build configuration

Setting amber to true changes these defaults:

- glvnd defaults to enabled
- the glvnd vendor name is set to "amber"
- the gallium and vulkan drivers are disabled
- prefer-iris defaults to false
- eglQueryString(EGL_VENDOR) returns "Mesa Project (Amber)"

The megadriver for the classic driver set will be installed to a file
name unique from Mesa main. Beyond that no attempt is made to use
filenames different from main - particularly not if glvnd is explicitly
disabled - so you would still need to configure your install paths
appropriately so things don't collide, if you want them to not collide.
But if you have that problem, consider that glvnd already solves it.

This has a quiet dependency on glapi and gbm's library API remaining
stable. gbm you could fix by linking it statically, glapi is a little
harder. I think the right move for glapi is to use glvnd's gldispatch
more directly, but that's not public API at the moment.

Reviewed-by: Emma Anholt <emma@anholt.net>
Reviewed-by: Eric Engestrom <eric@engestrom.ch>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10557>

meson.build

@@ -39,6 +39,13 @@ if get_option('layout') != 'mirror'
   error('`mirror` is the only build directory layout supported')
 endif
 
+amber = get_option('amber')
+if amber
+  package_version_suffix=' Amber'
+else
+  package_version_suffix=''
+endif
+
 # Arguments for the preprocessor, put these in a separate array from the C and
 # C++ (cpp in meson terminology) arguments since they need to be added to the
 # default arguments for both C and C++.
@@ -46,13 +53,18 @@ pre_args = [
   '-D__STDC_CONSTANT_MACROS',
   '-D__STDC_FORMAT_MACROS',
   '-D__STDC_LIMIT_MACROS',
-  '-DPACKAGE_VERSION="@0@"'.format(meson.project_version()),
+  '-DPACKAGE_VERSION="@0@@1@"'.format(meson.project_version(), package_version_suffix),
   '-DPACKAGE_BUGREPORT="https://gitlab.freedesktop.org/mesa/mesa/-/issues"',
 ]
 c_args = []
 cpp_args = []
 
 with_moltenvk_dir = get_option('moltenvk-dir')
+
+if amber
+  pre_args += '-DAMBER'
+endif
+
 with_vulkan_icd_dir = get_option('vulkan-icd-dir')
 with_tests = get_option('build-tests')
 with_aco_tests = get_option('build-aco-tests')
@@ -199,7 +211,9 @@ with_dri = dri_drivers.length() != 0
 
 gallium_drivers = get_option('gallium-drivers')
 if gallium_drivers.contains('auto')
-  if system_has_kms_drm
+  if amber
+    gallium_drivers = []
+  elif system_has_kms_drm
     # TODO: PPC, Sparc
     if ['x86', 'x86_64'].contains(host_machine.cpu_family())
       gallium_drivers = [
@@ -262,7 +276,9 @@ endif
 _vulkan_drivers = get_option('vulkan-drivers')
 if _vulkan_drivers.contains('auto')
   if system_has_kms_drm
-    if host_machine.cpu_family().startswith('x86')
+    if amber
+      _vulkan_drivers = []
+    elif host_machine.cpu_family().startswith('x86')
       _vulkan_drivers = ['amd', 'intel', 'swrast']
     elif ['arm', 'aarch64'].contains(host_machine.cpu_family())
       _vulkan_drivers = ['swrast']
@@ -531,8 +547,22 @@ if with_glx != 'disabled'
   endif
 endif
 
-with_glvnd = get_option('glvnd')
+_glvnd = get_option('glvnd')
+if _glvnd == 'true' or _glvnd == 'enabled' or (amber and _glvnd == 'auto')
+  with_glvnd = true
+else
+  with_glvnd = false
+endif
+
 glvnd_vendor_name = get_option('glvnd-vendor-name')
+if glvnd_vendor_name == 'auto'
+  if amber
+    glvnd_vendor_name = 'amber'
+  else
+    glvnd_vendor_name = 'mesa'
+  endif
+endif
+
 if with_glvnd
   if with_platform_windows
     error('glvnd cannot be used on Windows')

meson_options.txt

@@ -302,8 +302,9 @@ option(
 )
 option(
   'glvnd',
-  type : 'boolean',
-  value : false,
+  type : 'combo',
+  value : 'auto',
+  choices : ['auto', 'true', 'false', 'enabled', 'disabled'],
   description : 'Enable GLVND support.'
 )
 option(
@@ -321,7 +322,7 @@ option(
 option(
   'glvnd-vendor-name',
   type : 'string',
-  value : 'mesa',
+  value : 'auto',
   description : 'Vendor name string to use for glvnd libraries'
 )
 option(
@@ -457,14 +458,16 @@ option(
 )
 option(
   'prefer-iris',
-  type : 'boolean',
-  value : true,
+  type : 'combo',
+  value : 'auto',
+  choices : ['auto', 'true', 'false'],
   description : 'Prefer new Intel iris driver over older i965 driver'
 )
 option(
   'prefer-crocus',
-  type : 'boolean',
-  value : false,
+  type : 'combo',
+  value : 'auto',
+  choices : ['auto', 'true', 'false'],
   description : 'Prefer new crocus driver over older i965 driver for gen4-7'
 )
 option('egl-lib-suffix',
@@ -530,3 +533,9 @@ option(
   value : false,
   description : 'Build gallium VMware/svga driver with mksGuestStats instrumentation.'
 )
+option(
+  'amber',
+  type : 'boolean',
+  value : false,
+  description : 'Configure LTS build to coexist with Mesa >= 22.0'
+)

src/egl/main/egldefines.h

@@ -46,7 +46,11 @@ extern "C" {
 #define _EGL_MAX_PBUFFER_WIDTH 4096
 #define _EGL_MAX_PBUFFER_HEIGHT 4096
 
+#ifdef AMBER
+#define _EGL_VENDOR_STRING "Mesa Project (Amber)"
+#else
 #define _EGL_VENDOR_STRING "Mesa Project"
+#endif
 
 #ifdef __cplusplus
 }

src/egl/meson.build

@@ -165,7 +165,7 @@ else
   files_egl += [g_egldispatchstubs_h, g_egldispatchstubs_c]
   files_egl += files('main/eglglvnd.c', 'main/egldispatchstubs.c')
   glvnd_config = configuration_data()
-  glvnd_config.set('glvnd_vendor_name', get_option('glvnd-vendor-name'))
+  glvnd_config.set('glvnd_vendor_name', glvnd_vendor_name)
   configure_file(
     configuration: glvnd_config,
     input : 'main/50_mesa.json',

src/loader/meson.build

@@ -41,11 +41,19 @@ loader_c_args = [
   '-DDEFAULT_DRIVER_DIR="@0@"'.format(dri_search_path),
 ]
 
-if get_option('prefer-iris')
+_prefer_iris = get_option('prefer-iris')
+if _prefer_iris == 'auto'
+  _prefer_iris = amber ? 'false' : 'true'
+endif
+if _prefer_iris == 'true'
   loader_c_args += ['-DPREFER_IRIS']
 endif
 
-if get_option('prefer-crocus')
+_prefer_crocus = get_option('prefer-crocus')
+if _prefer_crocus == 'auto'
+  _prefer_crocus = 'false'
+endif
+if _prefer_crocus == 'true'
   loader_c_args += ['-DPREFER_CROCUS']
 endif
 

src/mesa/drivers/dri/meson.build

@@ -51,7 +51,7 @@ endif
 
 if _dri_drivers != []
   libmesa_dri_drivers = shared_library(
-    'mesa_dri_drivers',
+    '@0@_dri_drivers'.format(glvnd_vendor_name),
     [],
     link_whole : _dri_drivers,
     link_with : [