From 4c8d08d2294c042c276f945c11ea7c6dd605025d Mon Sep 17 00:00:00 2001
From: Christopher James Halse Rogers <christopher.halse.rogers@canonical.com>
Date: Fri, 5 Jul 2024 14:34:09 +1000
Subject: [PATCH 1/7] platform/DRMFormat: Don't require a `FormatInfo` for each
 format.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

We're now using `DRMFormat` in a situation (linux-dmabuf) where:
* We don't actually need to care about many the properties of the format, and
* We're processing formats submitted by cilents.

This means that the existing “throw an exception if we haven't got a `FormatInfo`”
approach works badly; we will disconnect clients with a Wayland internal error
if they submit buffers in a format we haven't explicitly listed, even though it
*would* work if we just treated the format as an opaque identifier.

So, don't do that anymore. Instead, store the fourcc code directly in `DRMFormat`
alongside the `FormatInfo` if it exists.

Fixes: #3462
---
 include/platform/mir/graphics/drm_formats.h |  1 +
 src/platform/graphics/drm_formats.cpp       | 51 ++++++++++++---------
 2 files changed, 31 insertions(+), 21 deletions(-)

diff --git a/include/platform/mir/graphics/drm_formats.h b/include/platform/mir/graphics/drm_formats.h
index 9344ec9c7d7..c582f330c75 100644
--- a/include/platform/mir/graphics/drm_formats.h
+++ b/include/platform/mir/graphics/drm_formats.h
@@ -54,6 +54,7 @@ class DRMFormat
 
     struct FormatInfo;
 private:
+    uint32_t fourcc;
     FormatInfo const* info;
 };
 
diff --git a/src/platform/graphics/drm_formats.cpp b/src/platform/graphics/drm_formats.cpp
index b8d7553c2d4..e0de256133b 100644
--- a/src/platform/graphics/drm_formats.cpp
+++ b/src/platform/graphics/drm_formats.cpp
@@ -67,8 +67,8 @@ struct mg::DRMFormat::FormatInfo
 {
     uint32_t format;
     bool has_alpha;
-    uint32_t opaque_equivalent;
-    uint32_t alpha_equivalent;
+    std::optional<uint32_t> opaque_equivalent;
+    std::optional<uint32_t> alpha_equivalent;
     std::optional<mg::DRMFormat::RGBComponentInfo> components;
 };
 
@@ -223,7 +223,7 @@ constexpr std::array const formats = {
         DRM_FORMAT_RGB565,
         false,
         DRM_FORMAT_RGB565,
-        DRM_FORMAT_INVALID,
+        {},
         mg::DRMFormat::RGBComponentInfo{
             5, 6, 5, {}
         },
@@ -232,7 +232,7 @@ constexpr std::array const formats = {
         DRM_FORMAT_BGR565,
         false,
         DRM_FORMAT_BGR565,
-        DRM_FORMAT_INVALID,
+        {},
         mg::DRMFormat::RGBComponentInfo{
             5, 6, 5, {}
         },
@@ -241,7 +241,7 @@ constexpr std::array const formats = {
         DRM_FORMAT_RGB888,
         false,
         DRM_FORMAT_RGB888,
-        DRM_FORMAT_INVALID,
+        {},
         mg::DRMFormat::RGBComponentInfo{
             8, 8, 8, {}
         },
@@ -250,7 +250,7 @@ constexpr std::array const formats = {
         DRM_FORMAT_BGR888,
         false,
         DRM_FORMAT_BGR888,
-        DRM_FORMAT_INVALID,
+        {},
         mg::DRMFormat::RGBComponentInfo{
             8, 8, 8, {}
         },
@@ -443,67 +443,76 @@ constexpr auto maybe_info_for_format(uint32_t fourcc_format) -> mg::DRMFormat::F
 
 }
 
-constexpr auto info_for_format(uint32_t fourcc_format) -> mg::DRMFormat::FormatInfo const&
+constexpr auto info_for_format(uint32_t fourcc_format) -> mg::DRMFormat::FormatInfo const*
 {
     auto const info = maybe_info_for_format(fourcc_format);
 
     if (info)
     {
-        return *info;
+        return info;
     }
-    BOOST_THROW_EXCEPTION((
-        std::runtime_error{
-            std::string{"Unsupported DRM format: "} + mg::drm_format_to_string(fourcc_format)}));
+    return nullptr;
 }
 
 }
 
 mg::DRMFormat::DRMFormat(uint32_t fourcc_format)
-    : info{&info_for_format(fourcc_format)}
+    : fourcc{fourcc_format},
+      info{info_for_format(fourcc_format)}
 {
 }
 
 auto mg::DRMFormat::name() const -> const char*
 {
-    return drm_format_to_string(info->format);
+    return drm_format_to_string(fourcc);
 }
 
 auto mg::DRMFormat::opaque_equivalent() const -> const std::optional<DRMFormat>
 {
-    if (info->opaque_equivalent != DRM_FORMAT_INVALID)
+    if (info)
     {
-        return DRMFormat{info->opaque_equivalent};
+        return info->opaque_equivalent.transform([](auto const& fourcc) { return DRMFormat{fourcc};});
     }
     return {};
 }
 
 auto mg::DRMFormat::alpha_equivalent() const -> const std::optional<DRMFormat>
 {
-    if (info->alpha_equivalent != DRM_FORMAT_INVALID)
+    if (info)
     {
-        return DRMFormat{info->alpha_equivalent};
+        return info->alpha_equivalent.transform([](auto const& fourcc) { return DRMFormat{fourcc};});
     }
     return {};
 }
 
 bool mg::DRMFormat::has_alpha() const
 {
-    return info->has_alpha;
+    if (info)
+    {
+        return info->has_alpha;
+    }
+    // The safe default if we don't know is “true”
+    return true;
 }
 
 auto mg::DRMFormat::components() const -> std::optional<RGBComponentInfo> const&
 {
-    return info->components;
+    static std::optional<RGBComponentInfo> no_components = std::nullopt;
+    if (info)
+    {
+        return info->components;
+    }
+    return no_components;
 }
 
 mg::DRMFormat::operator uint32_t() const
 {
-    return info->format;
+    return fourcc;
 }
 
 auto mg::DRMFormat::as_mir_format() const -> std::optional<MirPixelFormat>
 {
-    switch (info->format)
+    switch (fourcc)
     {
     case DRM_FORMAT_ARGB8888:
         return mir_pixel_format_argb_8888;

From 6b31e6eb385075b1330f6b8f7755c439cec0cf9b Mon Sep 17 00:00:00 2001
From: Christopher James Halse Rogers <christopher.halse.rogers@canonical.com>
Date: Mon, 8 Jul 2024 14:59:23 +1000
Subject: [PATCH 2/7] platform/DRMFormat: Defer format info lookup until
 requested

This way things which treat `DRMFormat` as entirely opaque don't pay for the extra
format information, and we can warn when the things that *do* care about the format
details try to look up details we haven't included yet.
---
 include/platform/mir/graphics/drm_formats.h   |  42 ++++--
 src/platform/graphics/drm_formats.cpp         | 130 ++++++++----------
 src/platform/graphics/linux_dmabuf.cpp        |  13 +-
 src/platform/symbols.map                      |   9 +-
 .../gbm-kms/server/buffer_allocator.cpp       |  31 +++--
 src/server/scene/basic_surface.cpp            |   4 +-
 6 files changed, 124 insertions(+), 105 deletions(-)

diff --git a/include/platform/mir/graphics/drm_formats.h b/include/platform/mir/graphics/drm_formats.h
index c582f330c75..55af23d1992 100644
--- a/include/platform/mir/graphics/drm_formats.h
+++ b/include/platform/mir/graphics/drm_formats.h
@@ -27,35 +27,47 @@ namespace mir::graphics
 class DRMFormat
 {
 public:
-    struct RGBComponentInfo
+    struct FormatInfo;
+    class Info
     {
-        uint32_t red_bits;
-        uint32_t green_bits;
-        uint32_t blue_bits;
-        std::optional<uint32_t> alpha_bits;
-    };
+    public:
+        struct RGBComponentInfo
+        {
+            uint32_t red_bits;
+            uint32_t green_bits;
+            uint32_t blue_bits;
+            std::optional<uint32_t> alpha_bits;
+        };
 
-    // This could be constexpr, at the cost of moving a bunch of implementation into the header
-    explicit DRMFormat(uint32_t fourcc_format);
+        auto opaque_equivalent() const -> std::optional<DRMFormat>;
+        auto alpha_equivalent() const -> std::optional<DRMFormat>;
 
-    auto name() const -> char const*;
+        bool has_alpha() const;
 
-    auto opaque_equivalent() const -> std::optional<DRMFormat> const;
-    auto alpha_equivalent() const -> std::optional<DRMFormat> const;
+        auto components() const -> std::optional<RGBComponentInfo> const&;
+    private:
+        friend class DRMFormat;
+        Info(FormatInfo const* info);
 
-    bool has_alpha() const;
+        FormatInfo const* info;
+    };
 
-    auto components() const -> std::optional<RGBComponentInfo> const&;
+    constexpr explicit DRMFormat(uint32_t fourcc_format)
+        : fourcc{fourcc_format}
+    {
+    }
+
+    auto name() const -> char const*;
+
+    auto info() const -> std::optional<Info const>;
 
     operator uint32_t() const;
 
     auto as_mir_format() const -> std::optional<MirPixelFormat>;
     static auto from_mir_format(MirPixelFormat format) -> DRMFormat;
 
-    struct FormatInfo;
 private:
     uint32_t fourcc;
-    FormatInfo const* info;
 };
 
 auto drm_modifier_to_string(uint64_t modifier) -> std::string;
diff --git a/src/platform/graphics/drm_formats.cpp b/src/platform/graphics/drm_formats.cpp
index e0de256133b..f27f2e0f688 100644
--- a/src/platform/graphics/drm_formats.cpp
+++ b/src/platform/graphics/drm_formats.cpp
@@ -69,7 +69,7 @@ struct mg::DRMFormat::FormatInfo
     bool has_alpha;
     std::optional<uint32_t> opaque_equivalent;
     std::optional<uint32_t> alpha_equivalent;
-    std::optional<mg::DRMFormat::RGBComponentInfo> components;
+    std::optional<Info::RGBComponentInfo> components;
 };
 
 namespace
@@ -80,7 +80,7 @@ constexpr std::array const formats = {
         false,
         DRM_FORMAT_XRGB4444,
         DRM_FORMAT_ARGB4444,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             4, 4, 4, {}
         },
     },
@@ -89,7 +89,7 @@ constexpr std::array const formats = {
         false,
         DRM_FORMAT_XBGR4444,
         DRM_FORMAT_ABGR4444,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             4, 4, 4, {}
         },
     },
@@ -98,7 +98,7 @@ constexpr std::array const formats = {
         false,
         DRM_FORMAT_RGBX4444,
         DRM_FORMAT_RGBA4444,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             4, 4, 4, {}
         },
     },
@@ -107,7 +107,7 @@ constexpr std::array const formats = {
         false,
         DRM_FORMAT_BGRX4444,
         DRM_FORMAT_BGRA4444,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             4, 4, 4, {}
         },
     },
@@ -116,7 +116,7 @@ constexpr std::array const formats = {
         true,
         DRM_FORMAT_XRGB4444,
         DRM_FORMAT_ARGB4444,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             4, 4, 4, 4
         },
     },
@@ -125,7 +125,7 @@ constexpr std::array const formats = {
         true,
         DRM_FORMAT_XBGR4444,
         DRM_FORMAT_ABGR4444,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             4, 4, 4, 4
         },
     },
@@ -134,7 +134,7 @@ constexpr std::array const formats = {
         true,
         DRM_FORMAT_RGBX4444,
         DRM_FORMAT_RGBA4444,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             4, 4, 4, 4
         },
     },
@@ -143,7 +143,7 @@ constexpr std::array const formats = {
         true,
         DRM_FORMAT_BGRX4444,
         DRM_FORMAT_BGRA4444,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             4, 4, 4, 4
         },
     },
@@ -152,7 +152,7 @@ constexpr std::array const formats = {
         false,
         DRM_FORMAT_XRGB1555,
         DRM_FORMAT_ARGB1555,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             5, 5, 5, {}
         },
     },
@@ -161,7 +161,7 @@ constexpr std::array const formats = {
         false,
         DRM_FORMAT_XBGR1555,
         DRM_FORMAT_ABGR1555,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             5, 5, 5, {}
         },
     },
@@ -170,7 +170,7 @@ constexpr std::array const formats = {
         false,
         DRM_FORMAT_RGBX5551,
         DRM_FORMAT_RGBA5551,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             5, 5, 5, {}
         },
     },
@@ -179,7 +179,7 @@ constexpr std::array const formats = {
         false,
         DRM_FORMAT_BGRX5551,
         DRM_FORMAT_BGRA5551,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             5, 5, 5, {}
         },
     },
@@ -188,7 +188,7 @@ constexpr std::array const formats = {
         true,
         DRM_FORMAT_XRGB1555,
         DRM_FORMAT_ARGB1555,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             5, 5, 5, 1
         },
     },
@@ -197,7 +197,7 @@ constexpr std::array const formats = {
         true,
         DRM_FORMAT_XBGR1555,
         DRM_FORMAT_ABGR1555,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             5, 5, 5, 1
         },
     },
@@ -206,7 +206,7 @@ constexpr std::array const formats = {
         true,
         DRM_FORMAT_RGBX5551,
         DRM_FORMAT_RGBA5551,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             5, 5, 5, 1
         },
     },
@@ -215,7 +215,7 @@ constexpr std::array const formats = {
         true,
         DRM_FORMAT_BGRX5551,
         DRM_FORMAT_BGRA5551,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             5, 5, 5, 1
         },
     },
@@ -224,7 +224,7 @@ constexpr std::array const formats = {
         false,
         DRM_FORMAT_RGB565,
         {},
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             5, 6, 5, {}
         },
     },
@@ -233,7 +233,7 @@ constexpr std::array const formats = {
         false,
         DRM_FORMAT_BGR565,
         {},
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             5, 6, 5, {}
         },
     },
@@ -242,7 +242,7 @@ constexpr std::array const formats = {
         false,
         DRM_FORMAT_RGB888,
         {},
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             8, 8, 8, {}
         },
     },
@@ -251,7 +251,7 @@ constexpr std::array const formats = {
         false,
         DRM_FORMAT_BGR888,
         {},
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             8, 8, 8, {}
         },
     },
@@ -260,7 +260,7 @@ constexpr std::array const formats = {
         false,
         DRM_FORMAT_XRGB8888,
         DRM_FORMAT_ARGB8888,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             8, 8, 8, {}
         },
     },
@@ -269,7 +269,7 @@ constexpr std::array const formats = {
         false,
         DRM_FORMAT_XBGR8888,
         DRM_FORMAT_ABGR8888,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             8, 8, 8, {}
         },
     },
@@ -278,7 +278,7 @@ constexpr std::array const formats = {
         false,
         DRM_FORMAT_RGBX8888,
         DRM_FORMAT_RGBA8888,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             8, 8, 8, {}
         },
     },
@@ -287,7 +287,7 @@ constexpr std::array const formats = {
         false,
         DRM_FORMAT_BGRX8888,
         DRM_FORMAT_BGRA8888,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             8, 8, 8, {}
         },
     },
@@ -296,7 +296,7 @@ constexpr std::array const formats = {
         true,
         DRM_FORMAT_XRGB8888,
         DRM_FORMAT_ARGB8888,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             8, 8, 8, 8
         },
     },
@@ -305,7 +305,7 @@ constexpr std::array const formats = {
         true,
         DRM_FORMAT_XBGR8888,
         DRM_FORMAT_ABGR8888,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             8, 8, 8, 8
         },
     },
@@ -314,7 +314,7 @@ constexpr std::array const formats = {
         true,
         DRM_FORMAT_RGBX8888,
         DRM_FORMAT_RGBA8888,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             8, 8, 8, 8
         },
     },
@@ -323,7 +323,7 @@ constexpr std::array const formats = {
         true,
         DRM_FORMAT_BGRX8888,
         DRM_FORMAT_BGRA8888,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             8, 8, 8, 8
         },
     },
@@ -332,7 +332,7 @@ constexpr std::array const formats = {
         false,
         DRM_FORMAT_XRGB2101010,
         DRM_FORMAT_ARGB2101010,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             10, 10, 10, {}
         },
     },
@@ -341,7 +341,7 @@ constexpr std::array const formats = {
         false,
         DRM_FORMAT_XBGR2101010,
         DRM_FORMAT_ABGR2101010,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             10, 10, 10, {}
         },
     },
@@ -350,7 +350,7 @@ constexpr std::array const formats = {
         false,
         DRM_FORMAT_RGBX1010102,
         DRM_FORMAT_RGBA1010102,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             10, 10, 10, {}
         },
     },
@@ -359,7 +359,7 @@ constexpr std::array const formats = {
         false,
         DRM_FORMAT_BGRX1010102,
         DRM_FORMAT_BGRA1010102,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             10, 10, 10, {}
         },
     },
@@ -368,7 +368,7 @@ constexpr std::array const formats = {
         true,
         DRM_FORMAT_XRGB2101010,
         DRM_FORMAT_ARGB2101010,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             10, 10, 10, 2
         },
     },
@@ -377,7 +377,7 @@ constexpr std::array const formats = {
         true,
         DRM_FORMAT_XBGR2101010,
         DRM_FORMAT_ABGR2101010,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             10, 10, 10, 2
         },
     },
@@ -386,7 +386,7 @@ constexpr std::array const formats = {
         true,
         DRM_FORMAT_RGBX1010102,
         DRM_FORMAT_RGBA1010102,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             10, 10, 10, 2
         },
     },
@@ -395,7 +395,7 @@ constexpr std::array const formats = {
         true,
         DRM_FORMAT_BGRX1010102,
         DRM_FORMAT_BGRA1010102,
-        mg::DRMFormat::RGBComponentInfo{
+        mg::DRMFormat::Info::RGBComponentInfo{
             10, 10, 10, 2
         },
     },
@@ -442,67 +442,45 @@ constexpr auto maybe_info_for_format(uint32_t fourcc_format) -> mg::DRMFormat::F
     }
 
 }
-
-constexpr auto info_for_format(uint32_t fourcc_format) -> mg::DRMFormat::FormatInfo const*
-{
-    auto const info = maybe_info_for_format(fourcc_format);
-
-    if (info)
-    {
-        return info;
-    }
-    return nullptr;
 }
 
+auto mg::DRMFormat::name() const -> const char*
+{
+    return drm_format_to_string(fourcc);
 }
 
-mg::DRMFormat::DRMFormat(uint32_t fourcc_format)
-    : fourcc{fourcc_format},
-      info{info_for_format(fourcc_format)}
+auto mg::DRMFormat::Info::opaque_equivalent() const -> std::optional<DRMFormat>
 {
+    return info->opaque_equivalent.transform([](auto const& fourcc) { return DRMFormat{fourcc};});
 }
 
-auto mg::DRMFormat::name() const -> const char*
+auto mg::DRMFormat::Info::alpha_equivalent() const -> std::optional<DRMFormat>
 {
-    return drm_format_to_string(fourcc);
+    return info->alpha_equivalent.transform([](auto const& fourcc) { return DRMFormat{fourcc};});
 }
 
-auto mg::DRMFormat::opaque_equivalent() const -> const std::optional<DRMFormat>
+bool mg::DRMFormat::Info::has_alpha() const
 {
-    if (info)
-    {
-        return info->opaque_equivalent.transform([](auto const& fourcc) { return DRMFormat{fourcc};});
-    }
-    return {};
+    return info->has_alpha;
 }
 
-auto mg::DRMFormat::alpha_equivalent() const -> const std::optional<DRMFormat>
+auto mg::DRMFormat::Info::components() const -> std::optional<Info::RGBComponentInfo> const&
 {
-    if (info)
-    {
-        return info->alpha_equivalent.transform([](auto const& fourcc) { return DRMFormat{fourcc};});
-    }
-    return {};
+    return info->components;
 }
 
-bool mg::DRMFormat::has_alpha() const
+mg::DRMFormat::Info::Info(FormatInfo const* info)
+    : info{info}
 {
-    if (info)
-    {
-        return info->has_alpha;
-    }
-    // The safe default if we don't know is “true”
-    return true;
 }
 
-auto mg::DRMFormat::components() const -> std::optional<RGBComponentInfo> const&
+auto mg::DRMFormat::info() const -> std::optional<Info const>
 {
-    static std::optional<RGBComponentInfo> no_components = std::nullopt;
-    if (info)
+    if (auto info = maybe_info_for_format(fourcc))
     {
-        return info->components;
+        return Info(info);
     }
-    return no_components;
+    return {};
 }
 
 mg::DRMFormat::operator uint32_t() const
diff --git a/src/platform/graphics/linux_dmabuf.cpp b/src/platform/graphics/linux_dmabuf.cpp
index d28b53903d2..81f80e22fb1 100644
--- a/src/platform/graphics/linux_dmabuf.cpp
+++ b/src/platform/graphics/linux_dmabuf.cpp
@@ -944,6 +944,17 @@ class DMABufTex : public mg::gl::Texture
     std::shared_ptr<mgc::EGLContextExecutor> const egl_delegate;
 };
 
+namespace
+{
+auto format_has_known_alpha(mg::DRMFormat format) -> std::optional<bool>
+{
+    /* TODO: It would be sensible to log when we don't have Info for the format,
+     * but this will happen a lot, so we would want some ratelimiting in the logger
+     */
+    return format.info().transform([](auto const& info) { return info.has_alpha(); });
+}
+}
+
 class DmabufTexBuffer :
     public mg::BufferBasic,
     public mg::DMABufBuffer
@@ -965,7 +976,7 @@ class DmabufTexBuffer :
           on_consumed{std::move(on_consumed)},
           on_release{std::move(on_release)},
           size_{dma_buf.size()},
-          has_alpha{dma_buf.format().has_alpha()},
+          has_alpha{format_has_known_alpha(dma_buf.format()).value_or(true)},  // Has-alpha is the safe default for unknown formats
           planes_{dma_buf.planes()},
           modifier_{dma_buf.modifier()},
           format_{dma_buf.format()}
diff --git a/src/platform/symbols.map b/src/platform/symbols.map
index 80961be7627..823491a8e08 100644
--- a/src/platform/symbols.map
+++ b/src/platform/symbols.map
@@ -10,14 +10,15 @@ MIR_PLATFORM_2.17 {
     mir::graphics::DMABufEGLProvider::DMABufEGLProvider*;
     mir::graphics::DMABufEGLProvider::as_texture*;
     mir::graphics::DRMFormat::DRMFormat*;
-    mir::graphics::DRMFormat::alpha_equivalent*;
+    mir::graphics::DRMFormat::Info::alpha_equivalent*;
     mir::graphics::DRMFormat::as_mir_format*;
-    mir::graphics::DRMFormat::components*;
+    mir::graphics::DRMFormat::Info::components*;
     mir::graphics::DRMFormat::from_mir_format*;
-    mir::graphics::DRMFormat::has_alpha*;
+    mir::graphics::DRMFormat::Info::has_alpha*;
     mir::graphics::DRMFormat::name*;
-    mir::graphics::DRMFormat::opaque_equivalent*;
+    mir::graphics::DRMFormat::Info::opaque_equivalent*;
     mir::graphics::DRMFormat::operator?unsigned?int*; /* Is actually operator uint32_t(), but 🤷 */
+    mir::graphics::DRMFormat::info*;
     mir::graphics::DisplayConfiguration::operator*;
     mir::graphics::DisplayConfiguration::valid*;
     mir::graphics::DisplayConfigurationOutput::extents*;
diff --git a/src/platforms/gbm-kms/server/buffer_allocator.cpp b/src/platforms/gbm-kms/server/buffer_allocator.cpp
index 4b4156c3725..be849f41205 100644
--- a/src/platforms/gbm-kms/server/buffer_allocator.cpp
+++ b/src/platforms/gbm-kms/server/buffer_allocator.cpp
@@ -350,14 +350,18 @@ class GBMOutputSurface : public mg::gl::OutputSurface
 
     static auto egl_config_for_format(EGLDisplay dpy, mg::GLConfig const& config, mg::DRMFormat format) -> std::optional<EGLConfig>
     {
-        mg::DRMFormat::RGBComponentInfo const default_components = { 8, 8, 8, 0};
+        mg::DRMFormat::Info::RGBComponentInfo const default_components = { 8, 8, 8, 0};
+        auto const components =
+            format.info().transform([](auto info) { return info.components(); })
+                .value_or(default_components)    // optional<optional<Components>> -> optional<Components>
+                .value_or(default_components);   // optional<Components> -> Components
 
         EGLint const config_attr[] = {
             EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
-            EGL_RED_SIZE, static_cast<EGLint>(format.components().value_or(default_components).red_bits),
-            EGL_GREEN_SIZE, static_cast<EGLint>(format.components().value_or(default_components).green_bits),
-            EGL_BLUE_SIZE, static_cast<EGLint>(format.components().value_or(default_components).blue_bits),
-            EGL_ALPHA_SIZE, static_cast<EGLint>(format.components().value_or(default_components).alpha_bits.value_or(0)),
+            EGL_RED_SIZE, static_cast<EGLint>(components.red_bits),
+            EGL_GREEN_SIZE, static_cast<EGLint>(components.green_bits),
+            EGL_BLUE_SIZE, static_cast<EGLint>(components.blue_bits),
+            EGL_ALPHA_SIZE, static_cast<EGLint>(components.alpha_bits.value_or(0)),
             EGL_DEPTH_SIZE, config.depth_buffer_bits(),
             EGL_STENCIL_SIZE, config.stencil_buffer_bits(),
             EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
@@ -405,11 +409,22 @@ class GBMOutputSurface : public mg::gl::OutputSurface
                 auto alternate_format =
                     [&]() -> std::optional<mg::DRMFormat>
                     {
-                        if (format.has_alpha())
+                        if (auto info = format.info())
                         {
-                            return format.opaque_equivalent();
+                            if (info->has_alpha())
+                            {
+                                return info->opaque_equivalent();
+                            }
+                            else
+                            {
+                                return info->alpha_equivalent();
+                            }
+                        }
+                        else
+                        {
+                            // If we don't know about the format, we can't find alternatives
+                            return {};
                         }
-                        return format.alpha_equivalent();
                     }();
 
                 if (alternate_format)
diff --git a/src/server/scene/basic_surface.cpp b/src/server/scene/basic_surface.cpp
index a58e54e40aa..2af9f2ce2bf 100644
--- a/src/server/scene/basic_surface.cpp
+++ b/src/server/scene/basic_surface.cpp
@@ -729,7 +729,9 @@ class SurfaceSnapshot : public mg::Renderable
     { return transformation_; }
 
     bool shaped() const override
-    { return entry->pixel_format().has_alpha(); }
+    {
+        return entry->pixel_format().info().transform([](auto info) { return info.has_alpha();}).value_or(true);
+    }
 
     mg::Renderable::ID id() const override
     { return id_; }

From 202b2b0afc535a3819c63ed04d911248a0e3009f Mon Sep 17 00:00:00 2001
From: Christopher James Halse Rogers <christopher.halse.rogers@canonical.com>
Date: Mon, 8 Jul 2024 17:51:52 +1000
Subject: [PATCH 3/7] platform/DRMFormat: Log when we're asked for missing
 format info

---
 src/platform/graphics/drm_formats.cpp | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/platform/graphics/drm_formats.cpp b/src/platform/graphics/drm_formats.cpp
index f27f2e0f688..5d20f3bfe49 100644
--- a/src/platform/graphics/drm_formats.cpp
+++ b/src/platform/graphics/drm_formats.cpp
@@ -24,6 +24,8 @@
 #include <array>
 #include <boost/throw_exception.hpp>
 
+#include "mir/log.h"
+
 #ifdef MIR_HAVE_DRM_GET_MODIFIER_NAME
 #include <xf86drm.h>
 #endif
@@ -480,6 +482,11 @@ auto mg::DRMFormat::info() const -> std::optional<Info const>
     {
         return Info(info);
     }
+    /* TODO: This could fire quite frequently.
+     * Ideally we would have a rate-limited (or once-per-format) logger, but for now, just
+     * throw it in the debug stream.
+     */
+    mir::log_debug("Detailed info for format %s missing; please report so this can be added", name());
     return {};
 }
 

From 0c244d653e962f3d67d38a6906d18f343ea0ca3c Mon Sep 17 00:00:00 2001
From: Christopher James Halse Rogers <christopher.halse.rogers@canonical.com>
Date: Tue, 9 Jul 2024 16:28:04 +1000
Subject: [PATCH 4/7] Bump mirplatform ABI; we've dropped some `DRMFormat`
 symbols

---
 debian/control                  | 4 ++--
 debian/libmirplatform28.install | 1 -
 debian/libmirplatform29.install | 1 +
 src/CMakeLists.txt              | 2 +-
 src/platform/symbols.map        | 2 +-
 5 files changed, 5 insertions(+), 5 deletions(-)
 delete mode 100644 debian/libmirplatform28.install
 create mode 100644 debian/libmirplatform29.install

diff --git a/debian/control b/debian/control
index a05b93b6888..e8350992dc3 100644
--- a/debian/control
+++ b/debian/control
@@ -77,7 +77,7 @@ Description: Display server for Ubuntu - server library
  .
  Contains the shared library needed by server applications for Mir.
 
-Package: libmirplatform28
+Package: libmirplatform29
 Section: libs
 Architecture: linux-any
 Multi-Arch: same
@@ -140,7 +140,7 @@ Section: libdevel
 Architecture: linux-any
 Multi-Arch: same
 Pre-Depends: ${misc:Pre-Depends}
-Depends: libmirplatform28 (= ${binary:Version}),
+Depends: libmirplatform29 (= ${binary:Version}),
          libmircommon-dev (= ${binary:Version}),
          libboost-program-options-dev,
          ${misc:Depends},
diff --git a/debian/libmirplatform28.install b/debian/libmirplatform28.install
deleted file mode 100644
index 8b2aeef1ca8..00000000000
--- a/debian/libmirplatform28.install
+++ /dev/null
@@ -1 +0,0 @@
-usr/lib/*/libmirplatform.so.28
diff --git a/debian/libmirplatform29.install b/debian/libmirplatform29.install
new file mode 100644
index 00000000000..aae6fdb0e79
--- /dev/null
+++ b/debian/libmirplatform29.install
@@ -0,0 +1 @@
+usr/lib/*/libmirplatform.so.29
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 498724de7ce..a05ca99d99e 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,5 +1,5 @@
 # We need MIRPLATFORM_ABI in both libmirplatform and the platform implementations.
-set(MIRPLATFORM_ABI 28)
+set(MIRPLATFORM_ABI 29)
 
 set(MIRAL_VERSION_MAJOR 5)
 set(MIRAL_VERSION_MINOR 1)
diff --git a/src/platform/symbols.map b/src/platform/symbols.map
index 823491a8e08..6cc7ac3e89c 100644
--- a/src/platform/symbols.map
+++ b/src/platform/symbols.map
@@ -1,4 +1,4 @@
-MIR_PLATFORM_2.17 {
+MIR_PLATFORM_2.18 {
  global:
   extern "C++" {
     mir::graphics::AtomicFrame::increment*;

From e380660e9721002f8de7d089b6ebcc67a5d80bef Mon Sep 17 00:00:00 2001
From: Christopher James Halse Rogers <christopher.halse.rogers@canonical.com>
Date: Fri, 12 Jul 2024 13:19:05 +1000
Subject: [PATCH 5/7] platform/DRMFormat: Log *only once per format* when we're
 asked for missing format info

---
 src/platform/graphics/drm_formats.cpp  | 16 +++++++++++-----
 src/platform/graphics/linux_dmabuf.cpp |  3 ---
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/src/platform/graphics/drm_formats.cpp b/src/platform/graphics/drm_formats.cpp
index 5d20f3bfe49..6cab34cc2cb 100644
--- a/src/platform/graphics/drm_formats.cpp
+++ b/src/platform/graphics/drm_formats.cpp
@@ -15,6 +15,7 @@
  */
 
 #include "mir/graphics/drm_formats.h"
+#include "mir/synchronised.h"
 #include "mir_toolkit/common.h"
 
 #include <cstdint>
@@ -22,6 +23,7 @@
 #include <stdexcept>
 #include <memory>
 #include <array>
+#include <unordered_set>
 #include <boost/throw_exception.hpp>
 
 #include "mir/log.h"
@@ -482,11 +484,15 @@ auto mg::DRMFormat::info() const -> std::optional<Info const>
     {
         return Info(info);
     }
-    /* TODO: This could fire quite frequently.
-     * Ideally we would have a rate-limited (or once-per-format) logger, but for now, just
-     * throw it in the debug stream.
-     */
-    mir::log_debug("Detailed info for format %s missing; please report so this can be added", name());
+
+    // Actually, we probably want `std::flat_set`, but no libstdc++ support yet.
+    static Synchronised<std::unordered_set<decltype(fourcc)>> unknown_formats_guard;
+    auto unknown_formats = unknown_formats_guard.lock();
+    if (!unknown_formats->contains(fourcc))
+    {
+        mir::log_warning("Detailed info for format %s missing; please report so this can be added", name());
+        unknown_formats->insert(fourcc);
+    }
     return {};
 }
 
diff --git a/src/platform/graphics/linux_dmabuf.cpp b/src/platform/graphics/linux_dmabuf.cpp
index 81f80e22fb1..9eea3a8bb4a 100644
--- a/src/platform/graphics/linux_dmabuf.cpp
+++ b/src/platform/graphics/linux_dmabuf.cpp
@@ -948,9 +948,6 @@ namespace
 {
 auto format_has_known_alpha(mg::DRMFormat format) -> std::optional<bool>
 {
-    /* TODO: It would be sensible to log when we don't have Info for the format,
-     * but this will happen a lot, so we would want some ratelimiting in the logger
-     */
     return format.info().transform([](auto const& info) { return info.has_alpha(); });
 }
 }

From f3a0b274b2e2d6f1e25a0a873510bad0c4725b22 Mon Sep 17 00:00:00 2001
From: Christopher James Halse Rogers <christopher.halse.rogers@canonical.com>
Date: Fri, 12 Jul 2024 13:21:57 +1000
Subject: [PATCH 6/7] trivial: Be more precise in returning `std::nullopt`

---
 src/platform/graphics/drm_formats.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/platform/graphics/drm_formats.cpp b/src/platform/graphics/drm_formats.cpp
index 6cab34cc2cb..a79c8932ec8 100644
--- a/src/platform/graphics/drm_formats.cpp
+++ b/src/platform/graphics/drm_formats.cpp
@@ -493,7 +493,7 @@ auto mg::DRMFormat::info() const -> std::optional<Info const>
         mir::log_warning("Detailed info for format %s missing; please report so this can be added", name());
         unknown_formats->insert(fourcc);
     }
-    return {};
+    return std::nullopt;
 }
 
 mg::DRMFormat::operator uint32_t() const

From 2d01c224173dd119cef6c6fdc798621a91a37a3d Mon Sep 17 00:00:00 2001
From: Christopher James Halse Rogers <christopher.halse.rogers@canonical.com>
Date: Mon, 15 Jul 2024 15:27:29 +1000
Subject: [PATCH 7/7] platform/DRMFormat: Point people at the GitHub new issue
 page for reporting missing formats

---
 src/platform/graphics/drm_formats.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/platform/graphics/drm_formats.cpp b/src/platform/graphics/drm_formats.cpp
index a79c8932ec8..42f549d7426 100644
--- a/src/platform/graphics/drm_formats.cpp
+++ b/src/platform/graphics/drm_formats.cpp
@@ -490,7 +490,8 @@ auto mg::DRMFormat::info() const -> std::optional<Info const>
     auto unknown_formats = unknown_formats_guard.lock();
     if (!unknown_formats->contains(fourcc))
     {
-        mir::log_warning("Detailed info for format %s missing; please report so this can be added", name());
+        mir::log_warning(
+            "Detailed info for format %s missing; please report this to https://github.com/canonical/mir/issues/new so this can be added", name());
         unknown_formats->insert(fourcc);
     }
     return std::nullopt;