swung0x48 c4be38005a [MG_Backend, MG_IntegrationTest, docs] (P7): the shader mip arm names the format it refused and renders through scratch when the image cannot be attached ...

Two Iris cases died on the Redmi (Adreno 830v2, DirectVulkan inproc) with
Fatal{UnmigratedVerb, "Magma:mipmap-shader-format-or-shape"}, deterministically and
under both run-ahead and lockstep, while the monolith arm and the whole host lane
stayed green. That one line was the entire evidence, and five disjunctions share the
name, so the one thing the device could have told us - which format, at what shape,
missing which feature bit - was the one thing it did not.

The name stays first and unprefixed, because the census, the retrace refusal tally
and every log grep key on the leading word; the driver's own answer follows it:
format enum, the view's storage format when it reinterprets, extent, levels, aspect,
view type, usage bits, layer range, and the names of the optimalTilingFeatures bits
that are ABSENT. The next device run reads a line instead of re-deriving it.

The refusal also loses half its territory. The shader arm rendered STRAIGHT INTO the
next level, which needs the image to carry COLOR_ATTACHMENT usage - and a texture
whose format the device declines as a colour attachment never gets that bit, so every
sampled-only texture without BLIT support fell into the refusal rather than into a
fallback. When the FORMAT can be rendered and only the IMAGE cannot, an owned scratch
attachment of the destination level's size takes the pass and vkCmdCopyImage moves the
mip in: a raw texel move, no conversion, texels still from GPU contents rather than a
staged shadow, and the scratch retires with the submit that consumes it - the shape the
multisample resolve arm above it already uses.

Neither shader arm had ever executed on the gate machine. lavapipe reports
BLIT_SRC|BLIT_DST for every colour format this binary can create, so GenerateWireMipmap
takes its native arm for all of them; GenerateMipmapPackedFloatPixels next door looks
like it covers the shader arm and does not, because R11F_G11F_B10F blits natively here
too. MGITEST_MAGMA_FORCE_SHADER_MIPMAP drops the native arm instead, one tier per shape
(1 = render into the level, 2 = render into scratch and copy back), read once and
compiled only into the disaggregated build.

F1WireScenario.GenerateMipmapWithoutNativeBlitPixels paints two different halves rather
than one flat colour - a pass that loses GL's row order averages to the same number
everywhere, and a single-colour assertion would call that correct - and asserts level
one per half. It is registered on the three Magma arms twice, ONE ENVIRONMENT EACH: the
knob changes how every mipmap in the process is generated, so a lane-wide flip would
silently retarget the four green mipmap entries beside it.

Red once (executed, reverted): with the scratch arm forced off, the tier-2 entry dies
with Fatal{UnmigratedVerb, "Magma:mipmap-shader-format-or-shape format=37 extent=8x8x1
levels=4 aspect=0x1 view=1 usage=0x17 layers=0+1/1 missing=DEPTH_STENCIL_ATTACHMENT"},
by name and with the shape in it; restored, the same filter is 8/8 green.

Gates: integration-magma-split 75 (+2), -spawn 54 (+2), -tcp 56 (+2), 0 red;
ctest -L unit 2402/2402; informational integration-magma-full-split 511, 0 red, 58 skip
(the new case skips where the knob is unset); fatal_census green (79 abort sites, 43
family words, 0 unmarked - no site added, the funnel is unchanged); link_ratchet
--assert-monotone unchanged at 186, p7-magma bucket 101.

2026-09-22 16:37:54 -04:00

..

Disaggregated

[MG_Backend, MG_IntegrationTest, docs] (P7): the shader mip arm names the format it refused and renders through scratch when the image cannot be attached

2026-09-22 16:37:54 -04:00