LibreMediaConverter/docs/api-37-emulator-crash.md

API 37 is not tested in CI: a crash in Google's android-37.0 emulator image

Status: open upstream, worked around by removing API 37 from the E2E matrix. The app itself is verified good on real API 37 hardware — this is an emulator bug only. Last verified: 2026-08-21, against emulator 37.1.11.0 and system image revision 6

minSdk is 33 and targetSdk is 37, and the E2E matrix in status_check.yml runs API 33 through 36. API 37 is deliberately absent. This is why.

Summary

The android-37.0 emulator system image crashes surfaceflinger in a loop. The app under test never gets a working framework, so every instrumented test fails regardless of what the app does. The bug is in the emulator image, not in this project.

The crash is an assertion inside the emulator's own gralloc implementation:

Executable:    /system/bin/surfaceflinger
signal 6 (SIGABRT), code -1 (SI_QUEUE), tid: RegionSampling
Abort message: 'Assertion failed: !rcEnc->featureInfo()->hasReadColorBufferDma'

  #03  mapper.ranchu.so   GoldfishMapper::readFromHost(cb_handle_t const&) const
  #04  mapper.ranchu.so   GoldfishMapper::GoldfishMapper()::'lambda'(...)::__invoke
  #05  libui.so           android::Gralloc5Mapper::lock(...)
  #06  libui.so           android::GraphicBufferMapper::lock(...)
  #07  libui.so           android::GraphicBuffer::lockAsync(...)
  #08  libui.so           android::GraphicBuffer::lock(...)
  #09  surfaceflinger     android::RegionSamplingThread::threadMain()

RegionSamplingThread is SystemUI's navigation-bar luma sampling. It calls GraphicBuffer::lock, which routes into GoldfishMapper::readFromHost, which asserts that the host has not negotiated the ReadColorBufferDma capability. On this image the host has, so the assertion fails and surfaceflinger aborts. It restarts and aborts again.

Impact

The failure surfaces in two different ways depending on how far the job gets, which is why it took several rounds to identify:

Guest RAM	Where it dies	What CI reports
1536 MB	during APK install	Unknown failure: cmd: Can't find service: package
2560 MB	during the test run	There were failing tests — all of them

At 2560 MB the install succeeds and the tests actually execute, then fail wholesale. The first failure in the report is misleading:

kotlin.UninitializedPropertyAccessException: lateinit property output has not
    been initialized
    at Media3EngineTest.tearDown(Media3EngineTest.kt:53)

java.lang.IllegalStateException: WorkManager is not initialized properly.
    You have explicitly disabled WorkManagerInitializer in your manifest, ...

Neither is a real defect in this project. tearDown throws because setUp never got far enough to assign output, and WorkManager's InitializationProvider never runs because content-provider installation fails on a framework whose surfaceflinger is crash-looping. The same tests pass at API 33, 34, 35, and 36 in the same CI run, and the first surfaceflinger abort is timestamped before the test results are reported.

This is not inference. The full suite was run against a physical API 37 device and passed — see Verified on real API 37 hardware below. ConversionWorkerTest and ConcatWorkerTest, which drive a real WorkManager round trip and are among the tests that failed this way in CI, both pass there.

Environment

Reproduced identically in two unrelated environments, so it is not specific to a host GPU, driver, or CI runner.

	GitHub Actions	Local workstation
Host	ubuntu-latest, no GPU	Fedora, Intel Iris Xe (TGL GT2)
Emulator	37.1.11.0 (build 15917651)	37.1.11.0 (build 15917651)
GPU mode	swiftshader_indirect	host
Result	boots, aborts during tests	aborts before boot completes

System image: system-images;android-37.0;google_apis;x86_64, Pkg.Revision=6, AndroidVersion.ApiLevel=37.0, AndroidVersion.ExtensionLevel=22

Build fingerprint: google/sdk_gphone64_x86_64/emu64xa:17/CE2A.260420.019/15611780:userdebug/dev-keys
Kernel Release:    6.12.58-android16-6-gccafb60de224-ab14828483

What was ruled out, and how

Each of these was tested rather than reasoned about, because the first three attempts at this bug were plausible fixes that turned out to address earlier, unrelated failures.

Guest memory. The emulator raises an undersized guest to a minimum on its own, but only for API levels it recognises, and it does not recognise "37.0". API 33 bumps to 2048 MB and 34/35/36 to 2560 MB, while API 37 logged no bump at all and ran at the pixel_6 default of 1536 MB. Setting ram-size: 2560M explicitly fixed that asymmetry and did change the outcome — the job got past install and into the test run — but it is not the underlying bug. At the moment of failure the guest reported MemTotal 2527392 kB with MemAvailable 1507104 kB: 1.5 GB free, and no OOM kills.

GPU mode. Both swiftshader_indirect and host crash, with the same assertion and the same frames. The crash is in the gralloc mapper, below the renderer.

Disabling the DMA feature. GLDMA is the host feature that most plausibly backs the guest's hasReadColorBufferDma. Launching with -feature -GLDMA was accepted by the emulator — the log confirms Feature 'GLDMA' (51) is overridden to 'disabled' — and surfaceflinger still aborted 13 times and the device never finished booting. Whatever sets that guest capability, it is not this flag.

An ATD image. google_atd / aosp_atd images are built for automated testing and ship without the SystemUI package set, which is what drives RegionSamplingThread in the first place. That would likely sidestep the bug class entirely, but no ATD image exists for android-37.0 — only google_apis, google_apis_playstore, the ps16k 16 KB-page variants, and Wear OS. Check again when revisiting; if an ATD image appears, try it before anything else here.

Verified on real API 37 hardware

The bug is confined to the emulator image. On 2026-08-21 the whole instrumented suite was run against a physical device and passed:

Device:  Pixel 10 Pro XL (mustang), arm64-v8a
Build:   google/mustang/mustang:17/CP2A.260805.005/15828068:user/release-keys
API:     37 (Android 17, codename REL -- a release build, not a preview)

./gradlew :app:connectedDebugAndroidTest -PabiFilters=arm64-v8a
  40 tests, 0 failures, 0 errors, 2 skipped        BUILD SUCCESSFUL

The two skips are RealMediaBenchmark.hardwareVersusSoftwareOnRealVideo and av1InputRoutesAccordingToDeviceDecodeSupport, which assumeTrue their sample files are present and skip when they are not. That is by design and unrelated to API level.

One harmless warning appears during the run and can be ignored: No UID for androidx.test.services in user 0, from an appops call the test services package makes before it is fully registered.

So the app is correct on Android 17. What is missing is only automated coverage in CI. Until the image is fixed, run the suite on a physical API 37 device before release; that is the substitute for the missing matrix row.

Reproducing it

Locally, with -gpu host so the emulator itself does not segfault on Intel graphics:

sdkmanager --install "system-images;android-37.0;google_apis;x86_64"
echo no | avdmanager create avd -n api37_repro \
    -k "system-images;android-37.0;google_apis;x86_64" -d pixel_6 --force

$ANDROID_HOME/emulator/emulator -avd api37_repro \
    -no-window -gpu host -noaudio -no-boot-anim -camera-back none -no-snapshot &

# Boot never completes. Count the aborts:
adb logcat -d -b crash | grep -c hasReadColorBufferDma

sys.boot_completed never reaches 1, pgrep -f system_server stays empty, and keystore2's watchdog logs await_boot_completed ... Overdue indefinitely.

To see the CI-side form instead, restore the API 37 row in the E2E matrix of status_check.yml (api-level: "37.0" — a bare 37 fails earlier still, during SDK setup, because there is no platforms;android-37).

Filing this upstream

Not yet filed. To file it:

1. Go to https://issuetracker.google.com/ and sign in with a Google account.
2. Choose Report an issue, then pick the component for the Android emulator — search the component picker for "Emulator"; it sits under the Android Studio component tree. If the picker is unclear, Android Studio's Help → Submit Feedback opens the same tracker with the component preselected, and the emulator's own Extended controls → Help → File a bug does likewise.
3. Title it for the mechanism, not the symptom, so it is searchable — for example: surfaceflinger aborts in GoldfishMapper::readFromHost (hasReadColorBufferDma) on android-37.0 google_apis x86_64.
4. Paste the assertion and backtrace from the top of this document, the environment table, and the reproduction steps above. State explicitly that it reproduces on two unrelated hosts under both GPU modes — that is the detail that stops it being closed as a local graphics problem.
5. List what was ruled out. Bugs that arrive with -feature -GLDMA already eliminated tend not to bounce back asking for it.
6. Attach:
   • the guest tombstone, via adb pull /data/tombstones (or the pbtombstone output the crash log names)
   • adb logcat -d -b crash > crash.txt
   • the emulator's own stdout log, captured by redirecting the launch command
   • the AVD's config.ini
   • a link to a failing CI job, which shows it on hardware you do not control: https://github.com/JMR-dev/LibreMediaConverter/actions/runs/32545625459/job/96963461184

Record the issue number here once filed.

When to revisit

Re-add the API 37 row when any of these happens:

• a new android-37.0 system image revision ships (this was revision 6)
• an ATD image appears for API 37
• the upstream issue is marked fixed

Until then the gap is narrower than the missing row suggests. targetSdk is 37, so the app is compiled and unit-tested against it; the API-dependent behaviour this matrix exists to exercise — the foreground service type, absent below 34, dataSync at 34, mediaProcessing from 35 — is covered at 35 and 36; and the full instrumented suite has been run green on real API 37 hardware. What is missing is automated API 37 coverage, so a regression there would not be caught by a pull request. Run the suite on a physical API 37 device before each release for as long as this row is absent.