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Quest Pro full 12 GiB RAM — rescue-only validation

Result

Kernel #253, payload quest-pro-kexec/out/ram12-253, registers the full stock physical memory map and passes repeated rescue-only memory tests with normal GPU/display kernel probing enabled. No alternate Android was launched during these experiments. Installed Android boots were used only as the kexec loader and recovery environment. No installed partitions or userdata images changed.

Image: build/runs/253/Image SHA-256: 5ded7a62459b5cd7d57f79a06e7bb4c6e798df8ead98d4a8c14fe0b187d266a8. Current target: full-RAM Android with Venus and CMS/updater disabled, out/ospayload-253-ram12-noupdater, tag ram253noupdater. User confirmed visible UI on the earlier combined Venus/full-RAM boot. The newest CMS/updater-removal boot completed initialization and a Venus encode test; final visibility awaits confirmation. Image replacements require fresh maps: prior payload maps are now stale. Fresh low6 rollback: out/ospayload-249-audio-noupdater. See the working-setup document. The archive/run identifier is 253; this Image's emitted kernel build counter is #250.

The physical RAM population is 12 GiB, with normal firmware/address-map holes, secure VM reservations, kernel metadata and splash reservations unavailable to the ordinary allocator. Final repeat MemTotal: 11,798,644 KiB (~11.25 GiB). This is NOT a claim that all 12 GiB can be freely allocated: protected/firmware memory must remain excluded. Dynamic secure reservations vary between boots.

Confirmed tests

  • ram12-253owned: read scan completed through physical 0x37ff00000 to exclusive end 0x380000000; 11,337 MiB free-page reads, 233 MiB reserved, 540 MiB unmapped, 176 MiB busy skipped. Pattern test allocated and verified all 11,008 requested MiB, zero mismatches, freed all pages.
  • Fresh boot ram12-253repeat: read scan completed again; 11,346 MiB reads, 233 MiB reserved, 532 MiB unmapped, 175 MiB busy skipped. Another 11,008 MiB allocation/write/read test passed with zero mismatches.
  • On that repeat boot, the strengthened pattern test filled ALL allocated blocks before verifying ANY block, with physical-address-dependent data and cache clean/invalidate between writes and reads. All 11,008 MiB passed again with zero mismatches. This also checks aliases between allocated banks.
  • Earlier graphics-isolated #249 boots passed two full scans plus 10,240 and 11,008 MiB pattern tests; these are superseded by the #253 tests with graphics probing enabled.

This is substantial allocation/read/write validation, not exhaustive testing of all bit patterns or long-duration thermal/retention behavior. Android with this full map has deliberately NOT been tested. Existing baseline Android payloads and image maps were left alone during rescue validation. Subsequent Android tests are recorded below; Venus/full-RAM coexistence is not yet verified.

Subsequent Android test (user authorized Android after rescue validation)

  • Venus-enabled out/ospayload-253-ram12, tag android253ram12: gadget gone at 40 s, no completed Android boot established. Retained log shows CPU0 soft lockup waiting in cross-CPU synchronization during BPF setup, with another CPU not responding. This is not proof of a DDR fault or a proven Venus root cause.
  • out/ospayload-253-ram12-novidc, tag android253ram12nv: same full memory map and splash guard, VIDC disabled, alive at 60 s, sys.boot_completed=1. MemTotal 11,786,344 KiB (~11.24 GiB), MemAvailable 9,050,508 KiB at initial check. Bluetooth ON, ALSA audio card registered. Proximity and ET/FT restored, user calibration true/both_temporal verified. No GPU timeout or soft-lockup messages in the subsequent check. Visual rendering awaits user confirmation.
  • No image replacements or installed partition changes for these tests.

Full-RAM Android success and restored Venus

Initial full-RAM Android rendering was blank and the next reboot soft-locked, even with VIDC disabled; low6 rollback restored visible UI. The expanded read-only stock snapshot in module/ion_secmap.c + module/smmu_secmap.h then added master-side secure SMMU page tables and cached secure table pools. Their private stock layouts are corroborated through public VMID/TTBR attrs, and table traversal is serialized with the driver's assignment/table locks. Only table pages/pools are read; mapped secure payload pages are not read.

The stock driver shares these pages with HLOS READ|WRITE but no EXEC. Reusing them as ordinary executable/JIT RAM after kexec is unsafe, despite passing read/write-only tests. The former ION/KGSL-buffer snapshot omitted these table pages. The first expanded snapshot found 30 table pages across nine domains: GPU, crypto, CVP, display, video and FastRPC. Current loader reserves their ranges along with the existing secure ION ranges; no giveback/SCM reassignment. This omission is strongly implicated in the Android-specific stalls; not every historical CPU/GPU fault has been individually attributed.

  • ram253sharedtables (VIDC disabled): Android boot complete, user confirmed visible UI. Live Android test allocated 4096 MiB, filled all blocks before verifying, zero mismatches, all pages freed. Boot completion, Bluetooth ON, audio card and stock-imported calibration remained intact afterward.
  • ram253sharedvenus and fresh ram253sharedvenusrepeat: VIDC enabled with qkx_venus_reload_first=1 and qkx_venus_no_pc=1. Both boots completed Android initialization and each passed three 1080p H.264 hardware encode/decode cycles (300 frames each, EOS=true); detached script STATUS=PASS.
  • Downloaded output work/venus-test/encoded-ram12-253.mp4: host ffprobe H.264/1920x1080/300 frames/10 seconds; FFmpeg full decode exit 0.
  • Latest MemTotal 11,774,064 KiB; no GPU timeout, stalled-SMMU or soft-lockup messages in the final checks. CVP firmware still reported a separate NOC error during boot; this is not a Venus test failure and remains open.
  • Visibility on the final combined Venus-enabled boot still needs user confirmation. Long-duration/other-codec/secure-DRM tests remain open.
  • The low-IOMMU-table-allocation diagnostic (#254 archive) did not resolve the stalls, was removed from source, and is not part of this working recipe.

Before reproduction, rebuild/use the expanded stock-compatible ion_secmap module as module/ion_secmap.ko. It is essential to the Android recipe. Historical rescue tests below preceded that snapshot enhancement.

Changes needed

  1. Restore full stock /memory/reg rather than the conservative low-6-GiB map. Use the values in out/captured/runtime.dtb, while retaining the otherwise working out/captured-low6 device tree setup: 
    0 80000000 0 39900000
2 0        1 80000000
0 c0000000 1 40000000
  2. Mark /reserved-memory/cont_splash_region@9c000000 no-map in the target DTB. This retains the 35 MiB inherited splash carveout and prevents the ordinary CPU linear map/allocator from treating it as general RAM.
  3. In oculus-linux-kernel/techpack/display/msm/sde/sde_kms.c, guard _sde_kms_release_splash_buffer() against freeing unmapped PFNs. The driver formerly called free_reserved_page() unconditionally. #253 checks the whole range with pfn_valid() before releasing anything, logs preserving unmapped splash memory 0x9c000000+0x2300000, and retains it.
  4. Continue the existing read-only stock secure-ION snapshot/no-map handoff in tools/run.sh; do not use GIVEBACK or arbitrary hypervisor reassignment.

The final payload does NOT disable GPU/display. QSEE and VIDC remain disabled for these RAM experiments. No Venus flags or Android initramfs are necessary. Normal cpuidle remains enabled; cpuidle.off=1 was only an unsuccessful intermediate diagnostic, not the fix.

Do NOT mark the DFPS-data region no-map with the unmodified PLL driver: drivers/clk/qcom/mdss/mdss-pll-util.c releases it via its own bootmem helper. That experiment caused an early new_slab page fault at the DFPS physical range. Restoring its original mapping removed that separate experimental bug.

The old RAM scanner was unsafe for this purpose

work/ram_scan2/ram_scan2.c previously read every valid PFN, including reserved carveouts and pages owned by drivers. A valid PFN/linear mapping does not mean HLOS may read its contents: secure GPU/ION pages can remain inaccessible. Raw scans stalled near splash RAM or upper driver-owned pages while rescue could otherwise remain alive. These failures alone are not proof of bad DDR.

The scanner now:

  • accepts an exclusive end_pfn (default physical end 0x380000000);
  • skips invalid/unmapped PFNs, PageReserved pages, and pages with a nonzero compound-aware page_count;
  • reports actual read/reserved/unmapped/busy totals.

The read-only free-page walk is diagnostic, not an ownership guarantee against concurrent allocation. The stronger test is work/ram_owned/ram_owned.c:

  • obtains 1 MiB blocks ONLY through Linux alloc_pages, keeping all blocks allocated simultaneously;
  • uses GFP_HIGHUSER_MOVABLE to permit movable/CMA allocation;
  • writes every 64-bit word with a physical-address-dependent pattern;
  • flushes through the standard ARM64 cache API, then verifies all blocks;
  • frees every allocation before returning. No arbitrary physical pages, device registers, or firmware-owned memory are written by this test. Both modules deliberately return -EAGAIN after their completed test so they can be inserted repeatedly without retaining a module. Thus insmod's Resource temporarily unavailable is expected ONLY when the corresponding done/DONE ... mismatches=0 kernel message is present.

Reproduce (never launch Android)

From quest-pro-kexec:

source /home/yusuf/kexectest/work/cycle.sh
rescue out/ram12-253 RAM_LOG_TAG shutdown_cdsp=1 shutdown_subsys=venus,npu
# Do NOT call launch or qkx-launch-android.

Standalone initramfs: out/ram12-rescue-stream-initramfs.gz, built from work/ram12-init.sh with initramfs/build.py and out/busybox, no --os-dir. It contains no Android image maps/launch scripts. It streams /dev/kmsg over UDP to 10.42.0.1:5140 and pins its diagnostic parent to CPU0.

To rebuild the payload (stock capture retained; no installed partition writes):

tools/prep.sh out/captured-low6 /home/yusuf/kexectest/build/runs/253/Image \
  out/ram12-rescue-stream-initramfs.gz out/NEW_RAM_PAYLOAD \
  'qkx_uart_dma_cleanup=1 qkx_skip_regulator_cleanup=1 deferred_probe_timeout=-1 qkx_stallmon=1 qkx_beat=1'
fdtput -t x out/NEW_RAM_PAYLOAD/boot.dtb /memory reg \
  $(fdtget -t x out/captured/runtime.dtb /memory reg)
fdtput -t s out/NEW_RAM_PAYLOAD/boot.dtb \
  /reserved-memory/cont_splash_region@9c000000 no-map ''
fdtput -t s out/NEW_RAM_PAYLOAD/boot.dtb /soc/qseecom@82400000 status disabled
fdtput -t s out/NEW_RAM_PAYLOAD/boot.dtb /soc/qcom,vidc@aa00000 status disabled

Build each external test module against build/diagnostic-kernel using the normal diagnostic clang/arm64 flags and M=work/ram_scan2 or M=work/ram_owned. Transfer through a short-lived host HTTP server; load from rescue /tmp:

taskset 10 insmod /tmp/ram_scan2.ko
taskset 20 insmod /tmp/ram_owned.ko mib=11008
dmesg | grep -E 'ramscan2: done|ramowned: (allocation complete|DONE)'

CPU pinning keeps log/network readers off a CPU potentially stalled by a read probe. Successful scan normally takes ~82 seconds; pattern test takes ~3–9 seconds. Logs: quest-pro-kexec/logs/ram12-253owned-udp.txt and ram12-253repeat-udp.txt. Kernel/test changes are uncommitted.

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