[Celegans12]

What

An R128 image instruction reads only words 0-3 of its T#, and the recompiler passes words 4-7 as zero (getImageResource), so DecodeTextureResource sees MAX_MIP 0. A 128-bit T# with a BASE_LEVEL above 0 then throws "starts past the surface's last mip level at levels that would move the surface's own". Ghost of Yōtei's streamed textures are like that: a 2048x2048 BC3 T# naming levels 2..11, of which only those 10 levels are resident.

• When words 4-7 are all zero and the T# would be refused this way, the decoder reads it as a 128-bit T#: MAX_MIP = LAST_LEVEL, with levels BASE..LAST described as their own chain (size shifted by BASE_LEVEL, MIN_LOD moved with it). It does this only when DescribeSurface gives each of those levels the same offset, size and tail slot as in the full chain (GFX10 places a chain from its last level up, so the resident levels start the allocation).
• Only 1D and 2D T#s are read this way. Any other type, a layout that doesn't match, or a T# with any of words 4-7 set still throws as before.
• The driver can't tell a 128-bit access from a 256-bit T# whose words 4-7 are zero, so it takes the 128-bit reading only where the 256-bit one is refused. A zero-tail T# starting at level 0 still decodes as one level.

Overlaps: #8564 adds EncodeTextureResource right below the refusal this PR changes (textual only). #7948 and #8429 edit other parts of DecodeTextureResource and its test and merge cleanly with this PR. #6977 edits the same function too but already conflicts with main.

Tested

• Windows 11 Pro, MinGW-w64 GCC 15.2.0, -DBUILD_TESTING=ON, RTX 3080 Laptop, based on main 65c393a: ctest 1834/1838. log_macros, log_macros_timestamps and agc_driver_image_array_window_past_layer_limit (doesn't compile with MinGW) fail on main too; guest_raise_in_host_code timed out under load and passed 3/3 alone.
• Linux (WSL, lavapipe), CI's job on the merge: 1772/1792; the same 20 fail on main.
• New R128 cases in agc_driver_graphics: the streamed T# decodes as 512x512 with 10 levels, each equal to level n+2 of the 12-level chain; a 1024x2048 T# of levels 4..11 as 64x128 with 8; MIN_LOD moves with the base level. They fail on main with the "starts past" message. The old 1920x1080 refusal case gets a PERF_MOD so it stays a 256-bit T#.
• PPSA26344: this reading in our tree's bindless path fixed black streamed rocks in the open world; not run on main.
• Not tested: AMD, Intel, console behaviour.

Checklist

• Based on current main; no other open PR implements the same functions
• One topic per PR; follow-ups go in a new PR
• No comments in code except technical debt
• Unimplemented paths throw (NotImplemented_nid_no_patch); silent stubs are listed under Silent stubs in their library's technical debt file
• No notes, investigation .md files or images added to the repository (attach them to this PR)
• New third-party code is a submodule built from source
• Generic behaviour, not specific to one title
• Depends on: none
• Fixes: none
• Unblocks: none
• GPUs tested: NVIDIA GeForce RTX 3080 Laptop GPU, driver 610.62, Windows 11 Pro; lavapipe (Mesa 25.2.8, WSL Ubuntu 24.04)
• AI-assisted: yes

[github-actions]

Other open pull requests touch the same code. Merging one will break the other, or both implement the same thing. If this one builds on them, list them in Depends on.

Pull request	Conflicting files (lines on main)	Same exports	Same new files
PR 8564	core/libs/prx/libSceAgcDriver/Graphics/src/GuestTextureResource.cpp L7

Some comparisons could not be completed because a pull request conflicts with the base branch. Review these shared files manually before concluding that there is no overlap.

Pull request	Shared files not compared
PR 6977	core/libs/prx/libSceAgcDriver/Graphics/src/GuestTextureResource.cpp
PR 9020	core/libs/prx/libSceAgcDriver/Graphics/src/GuestTextureResource.cpp
PR 9335	core/libs/prx/libSceAgcDriver/Graphics/src/GuestTextureResource.cpp
PR 9431	core/libs/prx/libSceAgcDriver/Graphics/src/GuestTextureResource.cpp
PR 9432	core/libs/prx/libSceAgcDriver/Graphics/src/GuestTextureResource.cpp
PR 9672	core/libs/prx/libSceAgcDriver/Graphics/src/GuestTextureResource.cpp
PR 9673	core/libs/prx/libSceAgcDriver/Graphics/src/GuestTextureResource.cpp
PR 9674	core/libs/prx/libSceAgcDriver/Graphics/src/GuestTextureResource.cpp
PR 9675	core/libs/prx/libSceAgcDriver/Graphics/src/GuestTextureResource.cpp
PR 9676	core/libs/prx/libSceAgcDriver/Graphics/src/GuestTextureResource.cpp
PR 9891	core/libs/prx/libSceAgcDriver/Graphics/src/GuestTextureResource.cpp core/libs/prx/libSceAgcDriver/tests/GuestTextureResource.cpp
PR 9892	core/libs/prx/libSceAgcDriver/Graphics/src/GuestTextureResource.cpp
PR 9893	core/libs/prx/libSceAgcDriver/Graphics/src/GuestTextureResource.cpp
PR 9895	core/libs/prx/libSceAgcDriver/Graphics/src/GuestTextureResource.cpp