nx2: shrink the graphics server pool to 2 GiB

The 12 GB layout added 8 GiB of DRAM for memory the Switch 2 graphics
server keeps, and the whole emulated DRAM is committed at boot, so Switch
2 games needed 20 GB of free commit ("Failed to allocate 20480 MiB of
backing memory" on PCs with 16 GB). With GPU-only regions backed as they
are written and sparse regions taking tiles from the game's memory, Mario
Kart World keeps ~1.1 GiB of the pool (texture pools it fills at boot,
flat afterwards) and Splatoon Raiders none. 2 GiB leaves room and brings
the commit to 14 GB. A title that runs the pool dry loses GPU writes
into its unbacked blocks and logs it once.

1 files changed, 4 insertions, 1 deletions

diff --git a/src/core/hle/kernel/board/nintendo/nx/k_system_control.h b/src/core/hle/kernel/board/nintendo/nx/k_system_control.h
index cc5572bde8..9aa527adb1 100644
--- a/src/core/hle/kernel/board/nintendo/nx/k_system_control.h
+++ b/src/core/hle/kernel/board/nintendo/nx/k_system_control.h
@@ -23,7 +23,10 @@ public:
 
     // Extra DRAM on the 12 GB layout for memory the Switch 2 graphics server keeps itself (nx2:gpu
     // 214 GPU-only regions). It sits in the non-secure system pool, outside the application pool.
-    static constexpr size_t Nx2GraphicsServerMemorySize = 8ULL * 1024 * 1024 * 1024; // 8_GiB
+    // GPU-only regions get memory only where guest memory is written and sparse regions take
+    // their tiles from the game's own memory (216), so much less of it is used (title 1: ~1.1 GiB,
+    // all of it at boot); all of it counts against the host's commit limit from boot.
+    static constexpr size_t Nx2GraphicsServerMemorySize = 2ULL * 1024 * 1024 * 1024; // 2_GiB
 
 public:
     class Init {